Research Article A Liquid Metal Conical Helical Antenna...
8
Research Article A Liquid Metal Conical Helical Antenna for Circular Polarization-Reconfigurable Antenna Yun Zhou, 1,2 Shaojun Fang, 1 Hongmei Liu, 1 and Shiqiang Fu 1 1 School of Information Science and Technology, Dalian Maritime University, Dalian, Liaoning 116026, China 2 School of Physics and Electronic Technology, Liaoning Normal University, Dalian, Liaoning 116026, China Correspondence should be addressed to Shaojun Fang; [email protected] Received 24 October 2015; Revised 18 December 2015; Accepted 29 December 2015 Academic Editor: Mourad Nedil Copyright © 2016 Yun Zhou et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A novel polarization-reconfigurable conical helical antenna based on the liquid metal is presented. e antenna is implemented by using truncated structure, variable pitch angle, a matching stub, and a mechanical autorotation device. e experimental results show that a good agreement between simulations and measurements is obtained. e gain of the antenna achieves higher than 8 dBi in the work band (1525–1660.5 MHz), and the 3 dB axial ratio (AR) bandwidth reaches 410 MHz. e polarization mode of the antenna can be switched between right-hand and leſt-hand circular polarization. 1. Introduction Antennas have played crucial roles in wireless communica- tion systems. With rapid increase of the number of antennas in communication system, it is a great challenge to improve the electromagnetic compatibility of communication sys- tems. Compared to traditional antennas, a reconfigurable antenna can act as several antennas by changing the antenna’s physical structure or incorporating switches. Since the con- cept of reconfigurable antenna was proposed by Schaubert in 1983 [1], it has attracted more and more attentions. Reconfigurable antennas include frequency-reconfigurable antenna, polarization-reconfigurable antenna, and pattern- reconfigurable antenna. A frequency-reconfigurable antenna using liquid metal as switching mechanism was proposed by Kelley et al. [2]. With the feature of easy reconstruction, liquid metal antennas attracted a growing number of scholars. In 2009, So et al. found that the liquid eutectic gallium indium alloy (EGaIn) has the ability to fabricate reconfigurable antenna because of its self-healing, which provides a new path for the realization of reconfigurable antenna. In the same year, a bendable frequency-reconfigurable monopole antenna was designed by embedding a liquid metal alloy into a polydimethylsiloxane (PDMS) substrate [3]. It is shown that the resonant frequency of the liquid metal antenna could be tuned by stretching the substrate and then altering the effective length of the antenna. In 2009, Cheng et al. proposed a foldable and stretchable liquid metal planar inverted cone antenna [4]. In 2011, a reconfigurable patch antenna was pro- posed by Mazlouman et al. which was fabricated by embed- ding liquid metal (eutectic gallium indium tin alloy, Galin- stan) in a silicone substrate [5]. Khan et al. presented a fre- quency-reconfigurable liquid metal antenna, which was in response to the pressure to adjust the electric length [6]. In 2012, Hayes et al. studied a flexible liquid metal alloy (EGaIn) microstrip patch antenna [7]. A tunable frequency liquid metal monopole antenna has been introduced by several research groups [8, 9]. In 2013 Morishita et al. designed a liq- uid metal monopole array with tunable frequency, gain, and beam steering [10]. A circular beam-steering reconfigurable antenna with liquid metal parasitic has been demonstrated by Rodrigo et al. [11]. However, the research on helical antenna based on liquid metal has not been found yet. Circularly polarized antennas are widely used for radar, navigation, and mobile systems [12]. An axial-mode helical antenna, firstly presented by Kraus [13], is an attractive can- didate for circularly polarized (CP) applications. A conical helical antenna is a kind of deformation of cylindrical helical antenna, which not only has the advantages of high gain and wide band, but also has the characteristic of sidelobe Hindawi Publishing Corporation International Journal of Antennas and Propagation Volume 2016, Article ID 3782373, 7 pages http://dx.doi.org/10.1155/2016/3782373
Transcript of Research Article A Liquid Metal Conical Helical Antenna...
Research ArticleA Liquid Metal Conical Helical Antenna forCircular Polarization-Reconfigurable Antenna
Yun Zhou12 Shaojun Fang1 Hongmei Liu1 and Shiqiang Fu1
1School of Information Science and Technology Dalian Maritime University Dalian Liaoning 116026 China2School of Physics and Electronic Technology Liaoning Normal University Dalian Liaoning 116026 China
Correspondence should be addressed to Shaojun Fang fangshjdlmueducn
Received 24 October 2015 Revised 18 December 2015 Accepted 29 December 2015
Academic Editor Mourad Nedil
Copyright copy 2016 Yun Zhou et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
A novel polarization-reconfigurable conical helical antenna based on the liquid metal is presentedThe antenna is implemented byusing truncated structure variable pitch angle a matching stub and a mechanical autorotation device The experimental resultsshow that a good agreement between simulations and measurements is obtained The gain of the antenna achieves higher than8 dBi in the work band (1525ndash16605MHz) and the 3 dB axial ratio (AR) bandwidth reaches 410MHz The polarization mode ofthe antenna can be switched between right-hand and left-hand circular polarization
1 Introduction
Antennas have played crucial roles in wireless communica-tion systems With rapid increase of the number of antennasin communication system it is a great challenge to improvethe electromagnetic compatibility of communication sys-tems Compared to traditional antennas a reconfigurableantenna can act as several antennas by changing the antennarsquosphysical structure or incorporating switches Since the con-cept of reconfigurable antenna was proposed by Schaubertin 1983 [1] it has attracted more and more attentionsReconfigurable antennas include frequency-reconfigurableantenna polarization-reconfigurable antenna and pattern-reconfigurable antenna A frequency-reconfigurable antennausing liquid metal as switching mechanism was proposed byKelley et al [2]With the feature of easy reconstruction liquidmetal antennas attracted a growing number of scholars In2009 So et al found that the liquid eutectic gallium indiumalloy (EGaIn) has the ability to fabricate reconfigurableantenna because of its self-healing which provides a newpath for the realization of reconfigurable antenna In thesame year a bendable frequency-reconfigurable monopoleantenna was designed by embedding a liquid metal alloy intoa polydimethylsiloxane (PDMS) substrate [3] It is shown thatthe resonant frequency of the liquid metal antenna could
be tuned by stretching the substrate and then altering theeffective length of the antenna In 2009 Cheng et al proposeda foldable and stretchable liquid metal planar inverted coneantenna [4] In 2011 a reconfigurable patch antenna was pro-posed by Mazlouman et al which was fabricated by embed-ding liquid metal (eutectic gallium indium tin alloy Galin-stan) in a silicone substrate [5] Khan et al presented a fre-quency-reconfigurable liquid metal antenna which was inresponse to the pressure to adjust the electric length [6] In2012 Hayes et al studied a flexible liquid metal alloy (EGaIn)microstrip patch antenna [7] A tunable frequency liquidmetal monopole antenna has been introduced by severalresearch groups [8 9] In 2013 Morishita et al designed a liq-uid metal monopole array with tunable frequency gain andbeam steering [10] A circular beam-steering reconfigurableantennawith liquidmetal parasitic has been demonstrated byRodrigo et al [11] However the research on helical antennabased on liquid metal has not been found yet
Circularly polarized antennas are widely used for radarnavigation and mobile systems [12] An axial-mode helicalantenna firstly presented by Kraus [13] is an attractive can-didate for circularly polarized (CP) applications A conicalhelical antenna is a kind of deformation of cylindrical helicalantenna which not only has the advantages of high gainand wide band but also has the characteristic of sidelobe
Hindawi Publishing CorporationInternational Journal of Antennas and PropagationVolume 2016 Article ID 3782373 7 pageshttpdxdoiorg10115520163782373
2 International Journal of Antennas and Propagation
R1h
0
AxisUpper fixed platePolyethylene foamPDMS elastomer
Ground plate
Z
X
Y
R1
R1
H
pl
pw
120572RGND
R9984001
(a)
Upper fixed plateAxis
Polyethylene foam Antenna
Matching stub
Ground plateLower fixed plate
Coaxial cableSubplate
Gear
(b)
Figure 1 Geometry of the proposed antenna (a) Panoramic view of the proposed antenna (b) Side view of the proposed antenna
suppression Conical helical reconfigurable antennas basedon liquid metal are very important value for applications
In this letter a polarization-reconfigurable conical helicalantenna using liquid metal enclosed in a polydimethylsilox-ane (PDMS) elastomer is introduced In order to verify theproposed method an antenna operating in the band (1525ndash16605MHz) was designed as an example and the polariza-tionmode of the antenna can be switched between right-handand left-hand circular polarization
2 Antenna Design
The proposed polarization-reconfigurable conical helicalantenna using liquid metal is enclosed in a tubular PDMSelastomer PDMS as an elastomer has been used to design thereconfigurable antenna [3 7] The relative dielectric constantof the PDMS is about 267 The outer diameter and innerdiameter of the PDMS elastomer are respectively 6mmand 4mm Under normal temperature liquid metal indiumgallium alloy (EGaIn) of low melting point is liquid Ifexposed to air EGaIn forms oxide surface and cannot flowThe liquid metal antenna combines the fluidity and ductilityof liquidmetal with the flexibility of the tubular PDMSwhichmakes the shape of the antenna easy to adjustTherefore it hasthe characteristics of reconfigurability
Considering portability the size of the antenna isdesigned as small as possible Variable pitch angle and trun-cated structure are used together not only to reduce theprofile but also to improve the antenna performance [11]Thegeometry of the proposed antenna is depicted in Figure 1(a)The parameter equation of conical helical antenna is [14]
119909 = (1198771015840+
119877 minus 1198771015840
2120587119873
119905) cos (119905)
119910 = (1198771015840+
119877 minus 1198771015840
2120587119873
119905) sin (119905)
119911 = 1198771015840 tan[(120572
0+
(1205721minus 1205720) 119905
2120587119873
)
120587
180
] 119905
(1)
where the variables 1198771015840 119877119873 1205720 and 120572
1denote respectively
the basal radius of the antenna the top radius of the antennathe helical turns the start pitch angle and the end pitch angleThe variable 119905 represents the radian of the spiral tube and itsscope is 0sim2120587119873
The ratio 119863120582 is an important parameter of the helicalantenna According to antenna theory when the ratio rangesfrom 025 to 042 the helical antenna will work in axial radi-ation mode [15] Beyond this range the helical antenna willno longer exhibit circular polarization characteristics andlobe patternmay appear distorted Under the demand of axialradiation pattern the basal radius of the antenna is chosen as1198771015840= 33mm the start pitch angle is 120572
0= 14∘ and the helical
turns are 119873 = 4 In order to reduce the profile and not todestroy the current distribution on the spiral line [16] the endvalue of 119905 is selected as 2120587times2The truncated structure is fabri-cated by cutting off two circles of the antenna and the remain-ing part is taken as the body of the conical helical antenna
The proposed antenna was composed of the ground platethe matching stub the supported foam and the liquid metalEGaIn enclosed in a tubular PDMS elastomer The tubularPDMS elastomer is wound on conical polyethylene foam(dielectric constant of 105) which mounted on a copperground plateThe feed network is designed by using a match-ing stub to achieve the excitation A short vertical feed linepenetrates the ground plate through a hole and is connectedto the matching stub as shown in Figure 1(a)
In order to design a polarization-reconfigurable helicalantenna both left and right spiral cylindrical grooves on theconical polyethylene foam were dug And the radii of thegrooves are both 6mm which could fit the tubular PDMSappropriately One end of the tubular PDMS elastomer isfastened on the upper plate which fixes together with the axisand the subplate the other end is fixed on the matching stubwhich closes to the ground plate and links the feed line formatching as shown in Figure 1 while the gear the groundplate and the polyethylene foam are fixed together Motordrives the gear through a belt and the gear would drivethe ground plate and polyethylene foam rotating with thePDMS elastomer In the process of spinning the matchingstub connected with the antenna could rotate clockwise or
International Journal of Antennas and Propagation 3
30
27
24
21
18
15
12
9
6
3
0
Frequency (GHz)
Axi
al ra
tio (d
B)
1205721 = 7∘
1205721 = 9∘
1205721 = 5∘
302826242220181614121008
Figure 2 Effects of the end pitch angle 1205721on the axial ratio of the
proposed helical antenna (1205720= 14∘ 119877 = 3mm and 1198771015840 = 33mm)
Table 1 Detailed dimensions of the proposed antenna
Parameters 1198771
1198771015840
1119877GND ℎ 119901119897
Value 147mm 30mm 150mm 9mm 242mmParameters 119877 119877
10158401205721
1205720
119901119908
Value 3mm 33mm 7∘ 14∘ 28mm
anticlockwise The axis and the subplate which is fastened toone end of the tubular PDMS elastomer are fixed By startingthe motor the rotation direction of circular polarization ofthe helical antenna can be changed
According to the simulation and based on the value of 1198771015840and the start pitch angle120572
0 it is found that the end pitch angle
1205721plays an important role in the current distribution so it can
affect the AR of the proposed antenna As shown in Figure 2the 3 dBARbandwidth is 248 at120572
1= 5∘ it can be enhanced
by increasing the value of 1205721 When 120572
1= 7∘ and 120572
1= 9∘ the
AR bandwidths are both around 335 Considering design-ing a low profile helical antenna we choose 120572
1= 7∘ in the
proposed antenna which makes the height of the antenna76mm
The significance of the top radius 119877 on the antennarsquos 3 dBAR performance is shown in Figure 3 It is seen that the 3 dBAR bandwidth is 335 at 119877 = 3 When 119877 = 5 and 119877 = 7the AR bandwidths are respectively 316 and 252 Bydecreasing the value of 119877 the 3 dB AR bandwidth can beenhanced
According to the value given above the simulation basedon HFSS is done It is found that the imaginary part of theantenna impedance can be controlled by changing the stubwidth 119901119908 as shown in Figure 4(a) And the real part can beregulated by mainly changing the stub length 119901119897 as shownin Figure 4(b) Table 1 shows the detailed dimensions of theproposed antenna
Frequency (GHz)302826242220181614121008
30
27
24
21
18
15
12
9
6
3
0
Axi
al ra
tio (d
B)
R = 3mmR = 5mmR = 7mm
Figure 3 Effects of the top radius 119877 on the axial ratio of the pro-posed helical antenna (120572
0= 14∘ 1205721= 7∘ and 1198771015840 = 33mm)
3 Experimental Results
To demonstrate the validity of the presented design strategya prototype of the antenna has been fabricated andmeasuredas shown in Figure 5
The measurement was carried out with Agilent N5230Avector network analyzer FromFigures 6(a) and 6(b) it can beseen that the simulated impedance bandwidth for 119878
11lt
minus15 dB is from 143GHz to 185GHz and the measuredimpedance bandwidth for 119878
11lt minus15 dB is from 141 GHz to
1805GHz for the LHCP while for the RHCP the simulatedimpedance bandwidth is from 143GHz to 185GHz andthe measured impedance bandwidth is from 141 GHz to181 GHz which show reasonable agreements between thesimulated andmeasured resultsThere exists a little frequencyoffset between simulation and measurement due to theassembly error
Figures 7(a) and 7(b) depict the simulated and measuredaxial ratio and the power gain of the proposed antenna againstfrequency for the LHCP and RHCP separatelyThe simulated3 dB axial ratio bandwidth is found to be nearly 335 and306 for the LHCP and RHCP respectively Within thewhole working band the measured results demonstrate thatthe peak gains are higher than 8 dB and the AR bandwidth isnearly 410MHzThemeasured results are in good agreementwith the simulated ones while the little discrepancy betweenthem can be mainly attributed to fabrication and measure-ment errors
The radiation patterns of both RHCP and LHCP at thecenter frequency 1593MHz are shown in Figures 8(a) 8(b)8(c) and 8(d) As can be seen themeasured 3 dBbeamwidthsfor LHCP are about 44∘ at 119909119900119911 plane and 564∘ at 119910119900119911 planewhile for RHCP 44∘ at119909119900119911 plane and 562∘ at119910119900119911 planeTherealso exists a little offset between simulation andmeasurementdue to the processing deviation in the antenna fabrication
4 International Journal of Antennas and Propagation
Frequency (GHz)302826242220181614121008
250
200
150
100
50
0
minus50
minus100
Inpu
t im
peda
nce (
Ω)
ImImIm
ReReRe
pl = 242mm pw = 26mmpl = 242mm pw = 28mmpl = 242mm pw = 30mm
(a)
Frequency (GHz)302826242220181614121008
200
150
100
50
0
minus50
minus100
Inpu
t im
peda
nce (
Ω)
ImImIm
ReReRe
pl = 22mm pw = 28mmpl = 242mm pw = 28mmpl = 262mm pw = 28mm
(b)
Figure 4 Input impedance as a function of the matching stub length and width (a) Changing 119901119908 (b) Changing 119901119897
Figure 5 Photograph of the proposed antenna
S 11
(dB)
Frequency (GHz)
0
minus5
minus10
minus15
minus20
minus25
minus30
302826242220181614121008060402
SimulatedMeasured
(a)
S 11
(dB)
0
5
minus5
minus10
minus15
minus20
minus25
minus30
03 06 09 12 15 18 21 24 27 30
Frequency (GHz)
SimulatedMeasured
(b)
Figure 6 The simulated and measured reflection coefficients (a) LHCP (b) RHCP
International Journal of Antennas and Propagation 5
80
70
60
50
40
30
20
10
0
Axi
al ra
tio (d
B)
Gai
n (d
B)
Measured ARSimulated AR
Measured gainSimulated gain
12
9
6
3
0
Frequency (GHz)302826242220181614121008060402
(a)
80
70
60
50
40
30
20
10
0
Axi
al ra
tio (d
B)
Frequency (GHz)
Measured ARSimulated AR
Measured gainSimulated gain
302826242220181614121008060402
Gai
n (d
B)
12
9
6
3
0
(b)
Figure 7 The simulated and measured axial ratio and gain (a) LHCP (b) RHCP
Table 2 Performance comparison of the state-of-the-art helical antenna
Ref StructureImpedancebandwidth|11987811| lt minus10 dB
AR bandwidth(AR lt 3 dB)
Height (1205820is the
wavelength at thecenter frequency)
Gain at center frequency (dB)
[18] Nonplanar6934217
421315
0331205820
02971205820
0291205820
45 dBi
[19] Nonplanar 923 32 0231205820
477 dBi
[20] Nonplanar 182 mdash 2961205820
13 dBi
[21] Nonplanar 128 mdash 1111205820
65 dBi
[17] Planar 54 34 0111205820
8 dBi
Our work Nonplanar356 (RHCP)36 (LHCP)(|11987811| lt minus15 dB)
265 041205820
8 dBi
Figure 9 depicts that the simulated efficiencies of the samestructure antennas vary with the frequency The conductorsare separately the aluminum the copper and the EGaIn Ascan be seen the efficiency of the EGaIn antenna is above 90within the whole working band
The simulated efficiencies of the antenna respectivelyby HFSS and CST are shown in Figure 10 It is shown thatwithin the whole working band the results keep consistentby different simulator
Table 2 summarizes the performance comparison of thestate-of-the-art helical antennas Compared to the othernonplanar helical antennas our proposed antenna clearlyexhibits the obvious advantages in terms of impedance andAR bandwidths It is seen that although the antenna in [17]retains wider impedance and AR bandwidths and has anobvious advantage than others its structure is planar Inaddition our antenna is a novel design that applied liquid
metal to design a polarization-reconfigurable helical antennaSo far the research on helical antenna based on liquid metalhas not been found yet
4 Conclusion
A novel polarization-reconfigurable conical helical antennawith liquid metal is achieved A truncated structure a var-iable pitch angle amatching stub and amechanical autorota-tion device are adopted in the proposed antennaThe circularpolarization radiation mode of the antenna can be switchedbetween the left hand and the right hand In the entire workband (1525ndash16605MHz) the gain of the antenna achieveshigher than 8 dBi and the 3 dB axial ratio (AR) bandwidthreaches 410MHz from 1340MHz to 1750MHz Experimentalresults confirm that the proposed liquid metal conical helical
6 International Journal of Antennas and Propagation
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(a)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(b)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(c)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus40
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(d)
Figure 8The simulated and measured radiation patterns (a) LHCP at 119909119900119911 plane (b) LHCP at 119910119900119911 plane (c) RHCP at 119909119900119911 plane (d) RHCPat 119910119900119911 plane
antenna can be a good candidate for circular polarization-reconfigurable antenna
Conflict of InterestsThe authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was supported jointly by the National Natural Sci-ence Foundation of China (no 61401056 and no 61571075)the Scientific Research Project of the Education Office ofLiaoning Province (no L2012171) and the Liaoning NormalUniversity Youth Project (no LS2014L003)
International Journal of Antennas and Propagation 7
Frequency (GHz)
CopperAluminum
3027242118151209060300
02
04
06
08
10
Effici
ency
()
EGaIn
Figure 9 Comparison of the efficiency among different conductors
Frequency (GHz)
HFSSCST
3027242118151209060300
00
02
04
06
08
10
Effici
ency
()
Figure 10 Comparison of the efficiency between HFSS and CST
References
[1] D Schaubert ldquoFrequency-agile polarization diverse microstripantennas and frequency scanned arraysrdquoUSUSPatent 43674741983
[2] M Kelley C Koo H McQuilken et al ldquoFrequency reconfig-urable patch antenna using liquid metal as switching mecha-nismrdquo Electronics Letters vol 49 no 22 pp 1370ndash1371 2013
[3] J-H So J Thelen A Qusba G J Hayes G Lazzi and M DDickey ldquoReversibly deformable and mechanically tunable flu-idic antennasrdquo Advanced Functional Materials vol 19 no 22pp 3632ndash3637 2009
[4] S Cheng Z Wu P Hallbjorner K Hjort and A RydbergldquoFoldable and stretchable liquid metal planar inverted coneantennardquo IEEE Transactions on Antennas and Propagation vol57 no 12 pp 3765ndash3771 2009
[5] S J Mazlouman X J Jiang A Mahanfar C Menon and R GVaughan ldquoA reconfigurable patch antenna using liquid metalembedded in a silicone substraterdquo IEEE Transactions on Anten-nas and Propagation vol 59 no 12 pp 4406ndash4412 2011
[6] M R Khan G J Hayes J-H So G Lazzi andM D Dickey ldquoAfrequency shifting liquid metal antenna with pressure respon-sivenessrdquoApplied Physics Letters vol 99 no 1 Article ID 0135012011
[7] G J Hayes J-H So A Qusba M D Dickey and G LazzildquoFlexible liquid metal alloy (EGaIn) microstrip patch antennardquoIEEE Transactions on Antennas and Propagation vol 60 no 5pp 2151ndash2156 2012
[8] A Dey R Guldiken and G Mumcu ldquoWideband frequencytunable liquid metal monopole antennardquo in Proceedings of theIEEE Antennas and Propagation Society International Sympo-sium (APSURSI rsquo13) pp 392ndash393 IEEE Orlando Fla USA July2013
[9] A M Morishita C K Y Kitamura A T Ohta and W A Shi-roma ldquoTwo-octave tunable liquid-metal monopole antennardquoElectronics Letters vol 50 no 1 pp 19ndash20 2014
[10] A M Morishita C K Y Kitamura A T Ohta and W AShiroma ldquoA liquid-metal monopole array with tunable fre-quency gain and beam steeringrdquo IEEE Antennas and WirelessPropagation Letters vol 12 no 1 pp 1388ndash1391 2013
[11] D Rodrigo L Jofre and B A Cetiner ldquoCircular beam-steeringreconfigurable antenna with liquid metal parasiticsrdquo IEEETransactions on Antennas and Propagation vol 60 no 4 pp1796ndash1802 2012
[12] Z-H Wu Y Lou J Bao and E K N Yung ldquoA circular patchfed by a switch line balun with printed L-probes for broadbandCP performancerdquo in Proceedings of the IEEE Antennas andPropagation Society International Symposium pp 1ndash4 IEEE SanDiego Calif USA July 2008
[13] J D Kraus ldquoHelical beam antennardquo Electronics vol 20 pp 109ndash111 1947
[14] S Fu Y Zhou S Fang and Y Cao ldquoDesign of low profileand variable pitch angle helical antenna for maritime satellitecommunicationsrdquo Chinese Journal of Radio Science vol 28 no1 pp 63ndash67 2013
[15] C A Balanis Antenna Theory Wiley-Interscience HobokenNJ USA 3rd edition 2005
[16] H Nakano H Takeda T Honma H Mimaki and J YamauchildquoExtremely low-profile helix radiating a circularly polarizedwaverdquo IEEE Transactions on Antennas and Propagation vol 39no 6 pp 754ndash757 1991
[17] Z Chen and Z Shen ldquoPlanar helical antenna of circular polar-izationrdquo IEEE Transactions on Antennas and Propagation vol63 no 10 pp 4315ndash4323 2015
[18] X Bai J Tang X Liang J Geng and R Jin ldquoCompact designof triple-band circularly polarized quadrifilar helix antennasrdquoIEEE Antennas and Wireless Propagation Letters vol 13 pp380ndash383 2014
[19] J Guo Y Yang Y Huang and B Sun ldquoSlot multi-arm helixantenna with simple and efficient feeding networkrdquo ElectronicsLetters vol 51 no 16 pp 1224ndash1226 2015
[20] L Liu Y Li Z Zhang and Z Feng ldquoCompact helical antennawith small ground fed by spiral-shaped microstrip linerdquo Elec-tronics Letters vol 50 no 5 pp 336ndash338 2014
[21] T L Zhang X Q Yang D L Fei and Z H Yan ldquoSingle-armhelical antenna with width of arm varying periodically for tiltedbeamrdquo Electronics Letters vol 51 no 10 pp 736ndash738 2015
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International Journal of
2 International Journal of Antennas and Propagation
R1h
0
AxisUpper fixed platePolyethylene foamPDMS elastomer
Ground plate
Z
X
Y
R1
R1
H
pl
pw
120572RGND
R9984001
(a)
Upper fixed plateAxis
Polyethylene foam Antenna
Matching stub
Ground plateLower fixed plate
Coaxial cableSubplate
Gear
(b)
Figure 1 Geometry of the proposed antenna (a) Panoramic view of the proposed antenna (b) Side view of the proposed antenna
suppression Conical helical reconfigurable antennas basedon liquid metal are very important value for applications
In this letter a polarization-reconfigurable conical helicalantenna using liquid metal enclosed in a polydimethylsilox-ane (PDMS) elastomer is introduced In order to verify theproposed method an antenna operating in the band (1525ndash16605MHz) was designed as an example and the polariza-tionmode of the antenna can be switched between right-handand left-hand circular polarization
2 Antenna Design
The proposed polarization-reconfigurable conical helicalantenna using liquid metal is enclosed in a tubular PDMSelastomer PDMS as an elastomer has been used to design thereconfigurable antenna [3 7] The relative dielectric constantof the PDMS is about 267 The outer diameter and innerdiameter of the PDMS elastomer are respectively 6mmand 4mm Under normal temperature liquid metal indiumgallium alloy (EGaIn) of low melting point is liquid Ifexposed to air EGaIn forms oxide surface and cannot flowThe liquid metal antenna combines the fluidity and ductilityof liquidmetal with the flexibility of the tubular PDMSwhichmakes the shape of the antenna easy to adjustTherefore it hasthe characteristics of reconfigurability
Considering portability the size of the antenna isdesigned as small as possible Variable pitch angle and trun-cated structure are used together not only to reduce theprofile but also to improve the antenna performance [11]Thegeometry of the proposed antenna is depicted in Figure 1(a)The parameter equation of conical helical antenna is [14]
119909 = (1198771015840+
119877 minus 1198771015840
2120587119873
119905) cos (119905)
119910 = (1198771015840+
119877 minus 1198771015840
2120587119873
119905) sin (119905)
119911 = 1198771015840 tan[(120572
0+
(1205721minus 1205720) 119905
2120587119873
)
120587
180
] 119905
(1)
where the variables 1198771015840 119877119873 1205720 and 120572
1denote respectively
the basal radius of the antenna the top radius of the antennathe helical turns the start pitch angle and the end pitch angleThe variable 119905 represents the radian of the spiral tube and itsscope is 0sim2120587119873
The ratio 119863120582 is an important parameter of the helicalantenna According to antenna theory when the ratio rangesfrom 025 to 042 the helical antenna will work in axial radi-ation mode [15] Beyond this range the helical antenna willno longer exhibit circular polarization characteristics andlobe patternmay appear distorted Under the demand of axialradiation pattern the basal radius of the antenna is chosen as1198771015840= 33mm the start pitch angle is 120572
0= 14∘ and the helical
turns are 119873 = 4 In order to reduce the profile and not todestroy the current distribution on the spiral line [16] the endvalue of 119905 is selected as 2120587times2The truncated structure is fabri-cated by cutting off two circles of the antenna and the remain-ing part is taken as the body of the conical helical antenna
The proposed antenna was composed of the ground platethe matching stub the supported foam and the liquid metalEGaIn enclosed in a tubular PDMS elastomer The tubularPDMS elastomer is wound on conical polyethylene foam(dielectric constant of 105) which mounted on a copperground plateThe feed network is designed by using a match-ing stub to achieve the excitation A short vertical feed linepenetrates the ground plate through a hole and is connectedto the matching stub as shown in Figure 1(a)
In order to design a polarization-reconfigurable helicalantenna both left and right spiral cylindrical grooves on theconical polyethylene foam were dug And the radii of thegrooves are both 6mm which could fit the tubular PDMSappropriately One end of the tubular PDMS elastomer isfastened on the upper plate which fixes together with the axisand the subplate the other end is fixed on the matching stubwhich closes to the ground plate and links the feed line formatching as shown in Figure 1 while the gear the groundplate and the polyethylene foam are fixed together Motordrives the gear through a belt and the gear would drivethe ground plate and polyethylene foam rotating with thePDMS elastomer In the process of spinning the matchingstub connected with the antenna could rotate clockwise or
International Journal of Antennas and Propagation 3
30
27
24
21
18
15
12
9
6
3
0
Frequency (GHz)
Axi
al ra
tio (d
B)
1205721 = 7∘
1205721 = 9∘
1205721 = 5∘
302826242220181614121008
Figure 2 Effects of the end pitch angle 1205721on the axial ratio of the
proposed helical antenna (1205720= 14∘ 119877 = 3mm and 1198771015840 = 33mm)
Table 1 Detailed dimensions of the proposed antenna
Parameters 1198771
1198771015840
1119877GND ℎ 119901119897
Value 147mm 30mm 150mm 9mm 242mmParameters 119877 119877
10158401205721
1205720
119901119908
Value 3mm 33mm 7∘ 14∘ 28mm
anticlockwise The axis and the subplate which is fastened toone end of the tubular PDMS elastomer are fixed By startingthe motor the rotation direction of circular polarization ofthe helical antenna can be changed
According to the simulation and based on the value of 1198771015840and the start pitch angle120572
0 it is found that the end pitch angle
1205721plays an important role in the current distribution so it can
affect the AR of the proposed antenna As shown in Figure 2the 3 dBARbandwidth is 248 at120572
1= 5∘ it can be enhanced
by increasing the value of 1205721 When 120572
1= 7∘ and 120572
1= 9∘ the
AR bandwidths are both around 335 Considering design-ing a low profile helical antenna we choose 120572
1= 7∘ in the
proposed antenna which makes the height of the antenna76mm
The significance of the top radius 119877 on the antennarsquos 3 dBAR performance is shown in Figure 3 It is seen that the 3 dBAR bandwidth is 335 at 119877 = 3 When 119877 = 5 and 119877 = 7the AR bandwidths are respectively 316 and 252 Bydecreasing the value of 119877 the 3 dB AR bandwidth can beenhanced
According to the value given above the simulation basedon HFSS is done It is found that the imaginary part of theantenna impedance can be controlled by changing the stubwidth 119901119908 as shown in Figure 4(a) And the real part can beregulated by mainly changing the stub length 119901119897 as shownin Figure 4(b) Table 1 shows the detailed dimensions of theproposed antenna
Frequency (GHz)302826242220181614121008
30
27
24
21
18
15
12
9
6
3
0
Axi
al ra
tio (d
B)
R = 3mmR = 5mmR = 7mm
Figure 3 Effects of the top radius 119877 on the axial ratio of the pro-posed helical antenna (120572
0= 14∘ 1205721= 7∘ and 1198771015840 = 33mm)
3 Experimental Results
To demonstrate the validity of the presented design strategya prototype of the antenna has been fabricated andmeasuredas shown in Figure 5
The measurement was carried out with Agilent N5230Avector network analyzer FromFigures 6(a) and 6(b) it can beseen that the simulated impedance bandwidth for 119878
11lt
minus15 dB is from 143GHz to 185GHz and the measuredimpedance bandwidth for 119878
11lt minus15 dB is from 141 GHz to
1805GHz for the LHCP while for the RHCP the simulatedimpedance bandwidth is from 143GHz to 185GHz andthe measured impedance bandwidth is from 141 GHz to181 GHz which show reasonable agreements between thesimulated andmeasured resultsThere exists a little frequencyoffset between simulation and measurement due to theassembly error
Figures 7(a) and 7(b) depict the simulated and measuredaxial ratio and the power gain of the proposed antenna againstfrequency for the LHCP and RHCP separatelyThe simulated3 dB axial ratio bandwidth is found to be nearly 335 and306 for the LHCP and RHCP respectively Within thewhole working band the measured results demonstrate thatthe peak gains are higher than 8 dB and the AR bandwidth isnearly 410MHzThemeasured results are in good agreementwith the simulated ones while the little discrepancy betweenthem can be mainly attributed to fabrication and measure-ment errors
The radiation patterns of both RHCP and LHCP at thecenter frequency 1593MHz are shown in Figures 8(a) 8(b)8(c) and 8(d) As can be seen themeasured 3 dBbeamwidthsfor LHCP are about 44∘ at 119909119900119911 plane and 564∘ at 119910119900119911 planewhile for RHCP 44∘ at119909119900119911 plane and 562∘ at119910119900119911 planeTherealso exists a little offset between simulation andmeasurementdue to the processing deviation in the antenna fabrication
4 International Journal of Antennas and Propagation
Frequency (GHz)302826242220181614121008
250
200
150
100
50
0
minus50
minus100
Inpu
t im
peda
nce (
Ω)
ImImIm
ReReRe
pl = 242mm pw = 26mmpl = 242mm pw = 28mmpl = 242mm pw = 30mm
(a)
Frequency (GHz)302826242220181614121008
200
150
100
50
0
minus50
minus100
Inpu
t im
peda
nce (
Ω)
ImImIm
ReReRe
pl = 22mm pw = 28mmpl = 242mm pw = 28mmpl = 262mm pw = 28mm
(b)
Figure 4 Input impedance as a function of the matching stub length and width (a) Changing 119901119908 (b) Changing 119901119897
Figure 5 Photograph of the proposed antenna
S 11
(dB)
Frequency (GHz)
0
minus5
minus10
minus15
minus20
minus25
minus30
302826242220181614121008060402
SimulatedMeasured
(a)
S 11
(dB)
0
5
minus5
minus10
minus15
minus20
minus25
minus30
03 06 09 12 15 18 21 24 27 30
Frequency (GHz)
SimulatedMeasured
(b)
Figure 6 The simulated and measured reflection coefficients (a) LHCP (b) RHCP
International Journal of Antennas and Propagation 5
80
70
60
50
40
30
20
10
0
Axi
al ra
tio (d
B)
Gai
n (d
B)
Measured ARSimulated AR
Measured gainSimulated gain
12
9
6
3
0
Frequency (GHz)302826242220181614121008060402
(a)
80
70
60
50
40
30
20
10
0
Axi
al ra
tio (d
B)
Frequency (GHz)
Measured ARSimulated AR
Measured gainSimulated gain
302826242220181614121008060402
Gai
n (d
B)
12
9
6
3
0
(b)
Figure 7 The simulated and measured axial ratio and gain (a) LHCP (b) RHCP
Table 2 Performance comparison of the state-of-the-art helical antenna
Ref StructureImpedancebandwidth|11987811| lt minus10 dB
AR bandwidth(AR lt 3 dB)
Height (1205820is the
wavelength at thecenter frequency)
Gain at center frequency (dB)
[18] Nonplanar6934217
421315
0331205820
02971205820
0291205820
45 dBi
[19] Nonplanar 923 32 0231205820
477 dBi
[20] Nonplanar 182 mdash 2961205820
13 dBi
[21] Nonplanar 128 mdash 1111205820
65 dBi
[17] Planar 54 34 0111205820
8 dBi
Our work Nonplanar356 (RHCP)36 (LHCP)(|11987811| lt minus15 dB)
265 041205820
8 dBi
Figure 9 depicts that the simulated efficiencies of the samestructure antennas vary with the frequency The conductorsare separately the aluminum the copper and the EGaIn Ascan be seen the efficiency of the EGaIn antenna is above 90within the whole working band
The simulated efficiencies of the antenna respectivelyby HFSS and CST are shown in Figure 10 It is shown thatwithin the whole working band the results keep consistentby different simulator
Table 2 summarizes the performance comparison of thestate-of-the-art helical antennas Compared to the othernonplanar helical antennas our proposed antenna clearlyexhibits the obvious advantages in terms of impedance andAR bandwidths It is seen that although the antenna in [17]retains wider impedance and AR bandwidths and has anobvious advantage than others its structure is planar Inaddition our antenna is a novel design that applied liquid
metal to design a polarization-reconfigurable helical antennaSo far the research on helical antenna based on liquid metalhas not been found yet
4 Conclusion
A novel polarization-reconfigurable conical helical antennawith liquid metal is achieved A truncated structure a var-iable pitch angle amatching stub and amechanical autorota-tion device are adopted in the proposed antennaThe circularpolarization radiation mode of the antenna can be switchedbetween the left hand and the right hand In the entire workband (1525ndash16605MHz) the gain of the antenna achieveshigher than 8 dBi and the 3 dB axial ratio (AR) bandwidthreaches 410MHz from 1340MHz to 1750MHz Experimentalresults confirm that the proposed liquid metal conical helical
6 International Journal of Antennas and Propagation
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(a)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(b)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(c)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus40
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(d)
Figure 8The simulated and measured radiation patterns (a) LHCP at 119909119900119911 plane (b) LHCP at 119910119900119911 plane (c) RHCP at 119909119900119911 plane (d) RHCPat 119910119900119911 plane
antenna can be a good candidate for circular polarization-reconfigurable antenna
Conflict of InterestsThe authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was supported jointly by the National Natural Sci-ence Foundation of China (no 61401056 and no 61571075)the Scientific Research Project of the Education Office ofLiaoning Province (no L2012171) and the Liaoning NormalUniversity Youth Project (no LS2014L003)
International Journal of Antennas and Propagation 7
Frequency (GHz)
CopperAluminum
3027242118151209060300
02
04
06
08
10
Effici
ency
()
EGaIn
Figure 9 Comparison of the efficiency among different conductors
Frequency (GHz)
HFSSCST
3027242118151209060300
00
02
04
06
08
10
Effici
ency
()
Figure 10 Comparison of the efficiency between HFSS and CST
References
[1] D Schaubert ldquoFrequency-agile polarization diverse microstripantennas and frequency scanned arraysrdquoUSUSPatent 43674741983
[2] M Kelley C Koo H McQuilken et al ldquoFrequency reconfig-urable patch antenna using liquid metal as switching mecha-nismrdquo Electronics Letters vol 49 no 22 pp 1370ndash1371 2013
[3] J-H So J Thelen A Qusba G J Hayes G Lazzi and M DDickey ldquoReversibly deformable and mechanically tunable flu-idic antennasrdquo Advanced Functional Materials vol 19 no 22pp 3632ndash3637 2009
[4] S Cheng Z Wu P Hallbjorner K Hjort and A RydbergldquoFoldable and stretchable liquid metal planar inverted coneantennardquo IEEE Transactions on Antennas and Propagation vol57 no 12 pp 3765ndash3771 2009
[5] S J Mazlouman X J Jiang A Mahanfar C Menon and R GVaughan ldquoA reconfigurable patch antenna using liquid metalembedded in a silicone substraterdquo IEEE Transactions on Anten-nas and Propagation vol 59 no 12 pp 4406ndash4412 2011
[6] M R Khan G J Hayes J-H So G Lazzi andM D Dickey ldquoAfrequency shifting liquid metal antenna with pressure respon-sivenessrdquoApplied Physics Letters vol 99 no 1 Article ID 0135012011
[7] G J Hayes J-H So A Qusba M D Dickey and G LazzildquoFlexible liquid metal alloy (EGaIn) microstrip patch antennardquoIEEE Transactions on Antennas and Propagation vol 60 no 5pp 2151ndash2156 2012
[8] A Dey R Guldiken and G Mumcu ldquoWideband frequencytunable liquid metal monopole antennardquo in Proceedings of theIEEE Antennas and Propagation Society International Sympo-sium (APSURSI rsquo13) pp 392ndash393 IEEE Orlando Fla USA July2013
[9] A M Morishita C K Y Kitamura A T Ohta and W A Shi-roma ldquoTwo-octave tunable liquid-metal monopole antennardquoElectronics Letters vol 50 no 1 pp 19ndash20 2014
[10] A M Morishita C K Y Kitamura A T Ohta and W AShiroma ldquoA liquid-metal monopole array with tunable fre-quency gain and beam steeringrdquo IEEE Antennas and WirelessPropagation Letters vol 12 no 1 pp 1388ndash1391 2013
[11] D Rodrigo L Jofre and B A Cetiner ldquoCircular beam-steeringreconfigurable antenna with liquid metal parasiticsrdquo IEEETransactions on Antennas and Propagation vol 60 no 4 pp1796ndash1802 2012
[12] Z-H Wu Y Lou J Bao and E K N Yung ldquoA circular patchfed by a switch line balun with printed L-probes for broadbandCP performancerdquo in Proceedings of the IEEE Antennas andPropagation Society International Symposium pp 1ndash4 IEEE SanDiego Calif USA July 2008
[13] J D Kraus ldquoHelical beam antennardquo Electronics vol 20 pp 109ndash111 1947
[14] S Fu Y Zhou S Fang and Y Cao ldquoDesign of low profileand variable pitch angle helical antenna for maritime satellitecommunicationsrdquo Chinese Journal of Radio Science vol 28 no1 pp 63ndash67 2013
[15] C A Balanis Antenna Theory Wiley-Interscience HobokenNJ USA 3rd edition 2005
[16] H Nakano H Takeda T Honma H Mimaki and J YamauchildquoExtremely low-profile helix radiating a circularly polarizedwaverdquo IEEE Transactions on Antennas and Propagation vol 39no 6 pp 754ndash757 1991
[17] Z Chen and Z Shen ldquoPlanar helical antenna of circular polar-izationrdquo IEEE Transactions on Antennas and Propagation vol63 no 10 pp 4315ndash4323 2015
[18] X Bai J Tang X Liang J Geng and R Jin ldquoCompact designof triple-band circularly polarized quadrifilar helix antennasrdquoIEEE Antennas and Wireless Propagation Letters vol 13 pp380ndash383 2014
[19] J Guo Y Yang Y Huang and B Sun ldquoSlot multi-arm helixantenna with simple and efficient feeding networkrdquo ElectronicsLetters vol 51 no 16 pp 1224ndash1226 2015
[20] L Liu Y Li Z Zhang and Z Feng ldquoCompact helical antennawith small ground fed by spiral-shaped microstrip linerdquo Elec-tronics Letters vol 50 no 5 pp 336ndash338 2014
[21] T L Zhang X Q Yang D L Fei and Z H Yan ldquoSingle-armhelical antenna with width of arm varying periodically for tiltedbeamrdquo Electronics Letters vol 51 no 10 pp 736ndash738 2015
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
International Journal of Antennas and Propagation 3
30
27
24
21
18
15
12
9
6
3
0
Frequency (GHz)
Axi
al ra
tio (d
B)
1205721 = 7∘
1205721 = 9∘
1205721 = 5∘
302826242220181614121008
Figure 2 Effects of the end pitch angle 1205721on the axial ratio of the
proposed helical antenna (1205720= 14∘ 119877 = 3mm and 1198771015840 = 33mm)
Table 1 Detailed dimensions of the proposed antenna
Parameters 1198771
1198771015840
1119877GND ℎ 119901119897
Value 147mm 30mm 150mm 9mm 242mmParameters 119877 119877
10158401205721
1205720
119901119908
Value 3mm 33mm 7∘ 14∘ 28mm
anticlockwise The axis and the subplate which is fastened toone end of the tubular PDMS elastomer are fixed By startingthe motor the rotation direction of circular polarization ofthe helical antenna can be changed
According to the simulation and based on the value of 1198771015840and the start pitch angle120572
0 it is found that the end pitch angle
1205721plays an important role in the current distribution so it can
affect the AR of the proposed antenna As shown in Figure 2the 3 dBARbandwidth is 248 at120572
1= 5∘ it can be enhanced
by increasing the value of 1205721 When 120572
1= 7∘ and 120572
1= 9∘ the
AR bandwidths are both around 335 Considering design-ing a low profile helical antenna we choose 120572
1= 7∘ in the
proposed antenna which makes the height of the antenna76mm
The significance of the top radius 119877 on the antennarsquos 3 dBAR performance is shown in Figure 3 It is seen that the 3 dBAR bandwidth is 335 at 119877 = 3 When 119877 = 5 and 119877 = 7the AR bandwidths are respectively 316 and 252 Bydecreasing the value of 119877 the 3 dB AR bandwidth can beenhanced
According to the value given above the simulation basedon HFSS is done It is found that the imaginary part of theantenna impedance can be controlled by changing the stubwidth 119901119908 as shown in Figure 4(a) And the real part can beregulated by mainly changing the stub length 119901119897 as shownin Figure 4(b) Table 1 shows the detailed dimensions of theproposed antenna
Frequency (GHz)302826242220181614121008
30
27
24
21
18
15
12
9
6
3
0
Axi
al ra
tio (d
B)
R = 3mmR = 5mmR = 7mm
Figure 3 Effects of the top radius 119877 on the axial ratio of the pro-posed helical antenna (120572
0= 14∘ 1205721= 7∘ and 1198771015840 = 33mm)
3 Experimental Results
To demonstrate the validity of the presented design strategya prototype of the antenna has been fabricated andmeasuredas shown in Figure 5
The measurement was carried out with Agilent N5230Avector network analyzer FromFigures 6(a) and 6(b) it can beseen that the simulated impedance bandwidth for 119878
11lt
minus15 dB is from 143GHz to 185GHz and the measuredimpedance bandwidth for 119878
11lt minus15 dB is from 141 GHz to
1805GHz for the LHCP while for the RHCP the simulatedimpedance bandwidth is from 143GHz to 185GHz andthe measured impedance bandwidth is from 141 GHz to181 GHz which show reasonable agreements between thesimulated andmeasured resultsThere exists a little frequencyoffset between simulation and measurement due to theassembly error
Figures 7(a) and 7(b) depict the simulated and measuredaxial ratio and the power gain of the proposed antenna againstfrequency for the LHCP and RHCP separatelyThe simulated3 dB axial ratio bandwidth is found to be nearly 335 and306 for the LHCP and RHCP respectively Within thewhole working band the measured results demonstrate thatthe peak gains are higher than 8 dB and the AR bandwidth isnearly 410MHzThemeasured results are in good agreementwith the simulated ones while the little discrepancy betweenthem can be mainly attributed to fabrication and measure-ment errors
The radiation patterns of both RHCP and LHCP at thecenter frequency 1593MHz are shown in Figures 8(a) 8(b)8(c) and 8(d) As can be seen themeasured 3 dBbeamwidthsfor LHCP are about 44∘ at 119909119900119911 plane and 564∘ at 119910119900119911 planewhile for RHCP 44∘ at119909119900119911 plane and 562∘ at119910119900119911 planeTherealso exists a little offset between simulation andmeasurementdue to the processing deviation in the antenna fabrication
4 International Journal of Antennas and Propagation
Frequency (GHz)302826242220181614121008
250
200
150
100
50
0
minus50
minus100
Inpu
t im
peda
nce (
Ω)
ImImIm
ReReRe
pl = 242mm pw = 26mmpl = 242mm pw = 28mmpl = 242mm pw = 30mm
(a)
Frequency (GHz)302826242220181614121008
200
150
100
50
0
minus50
minus100
Inpu
t im
peda
nce (
Ω)
ImImIm
ReReRe
pl = 22mm pw = 28mmpl = 242mm pw = 28mmpl = 262mm pw = 28mm
(b)
Figure 4 Input impedance as a function of the matching stub length and width (a) Changing 119901119908 (b) Changing 119901119897
Figure 5 Photograph of the proposed antenna
S 11
(dB)
Frequency (GHz)
0
minus5
minus10
minus15
minus20
minus25
minus30
302826242220181614121008060402
SimulatedMeasured
(a)
S 11
(dB)
0
5
minus5
minus10
minus15
minus20
minus25
minus30
03 06 09 12 15 18 21 24 27 30
Frequency (GHz)
SimulatedMeasured
(b)
Figure 6 The simulated and measured reflection coefficients (a) LHCP (b) RHCP
International Journal of Antennas and Propagation 5
80
70
60
50
40
30
20
10
0
Axi
al ra
tio (d
B)
Gai
n (d
B)
Measured ARSimulated AR
Measured gainSimulated gain
12
9
6
3
0
Frequency (GHz)302826242220181614121008060402
(a)
80
70
60
50
40
30
20
10
0
Axi
al ra
tio (d
B)
Frequency (GHz)
Measured ARSimulated AR
Measured gainSimulated gain
302826242220181614121008060402
Gai
n (d
B)
12
9
6
3
0
(b)
Figure 7 The simulated and measured axial ratio and gain (a) LHCP (b) RHCP
Table 2 Performance comparison of the state-of-the-art helical antenna
Ref StructureImpedancebandwidth|11987811| lt minus10 dB
AR bandwidth(AR lt 3 dB)
Height (1205820is the
wavelength at thecenter frequency)
Gain at center frequency (dB)
[18] Nonplanar6934217
421315
0331205820
02971205820
0291205820
45 dBi
[19] Nonplanar 923 32 0231205820
477 dBi
[20] Nonplanar 182 mdash 2961205820
13 dBi
[21] Nonplanar 128 mdash 1111205820
65 dBi
[17] Planar 54 34 0111205820
8 dBi
Our work Nonplanar356 (RHCP)36 (LHCP)(|11987811| lt minus15 dB)
265 041205820
8 dBi
Figure 9 depicts that the simulated efficiencies of the samestructure antennas vary with the frequency The conductorsare separately the aluminum the copper and the EGaIn Ascan be seen the efficiency of the EGaIn antenna is above 90within the whole working band
The simulated efficiencies of the antenna respectivelyby HFSS and CST are shown in Figure 10 It is shown thatwithin the whole working band the results keep consistentby different simulator
Table 2 summarizes the performance comparison of thestate-of-the-art helical antennas Compared to the othernonplanar helical antennas our proposed antenna clearlyexhibits the obvious advantages in terms of impedance andAR bandwidths It is seen that although the antenna in [17]retains wider impedance and AR bandwidths and has anobvious advantage than others its structure is planar Inaddition our antenna is a novel design that applied liquid
metal to design a polarization-reconfigurable helical antennaSo far the research on helical antenna based on liquid metalhas not been found yet
4 Conclusion
A novel polarization-reconfigurable conical helical antennawith liquid metal is achieved A truncated structure a var-iable pitch angle amatching stub and amechanical autorota-tion device are adopted in the proposed antennaThe circularpolarization radiation mode of the antenna can be switchedbetween the left hand and the right hand In the entire workband (1525ndash16605MHz) the gain of the antenna achieveshigher than 8 dBi and the 3 dB axial ratio (AR) bandwidthreaches 410MHz from 1340MHz to 1750MHz Experimentalresults confirm that the proposed liquid metal conical helical
6 International Journal of Antennas and Propagation
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(a)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(b)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(c)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus40
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(d)
Figure 8The simulated and measured radiation patterns (a) LHCP at 119909119900119911 plane (b) LHCP at 119910119900119911 plane (c) RHCP at 119909119900119911 plane (d) RHCPat 119910119900119911 plane
antenna can be a good candidate for circular polarization-reconfigurable antenna
Conflict of InterestsThe authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was supported jointly by the National Natural Sci-ence Foundation of China (no 61401056 and no 61571075)the Scientific Research Project of the Education Office ofLiaoning Province (no L2012171) and the Liaoning NormalUniversity Youth Project (no LS2014L003)
International Journal of Antennas and Propagation 7
Frequency (GHz)
CopperAluminum
3027242118151209060300
02
04
06
08
10
Effici
ency
()
EGaIn
Figure 9 Comparison of the efficiency among different conductors
Frequency (GHz)
HFSSCST
3027242118151209060300
00
02
04
06
08
10
Effici
ency
()
Figure 10 Comparison of the efficiency between HFSS and CST
References
[1] D Schaubert ldquoFrequency-agile polarization diverse microstripantennas and frequency scanned arraysrdquoUSUSPatent 43674741983
[2] M Kelley C Koo H McQuilken et al ldquoFrequency reconfig-urable patch antenna using liquid metal as switching mecha-nismrdquo Electronics Letters vol 49 no 22 pp 1370ndash1371 2013
[3] J-H So J Thelen A Qusba G J Hayes G Lazzi and M DDickey ldquoReversibly deformable and mechanically tunable flu-idic antennasrdquo Advanced Functional Materials vol 19 no 22pp 3632ndash3637 2009
[4] S Cheng Z Wu P Hallbjorner K Hjort and A RydbergldquoFoldable and stretchable liquid metal planar inverted coneantennardquo IEEE Transactions on Antennas and Propagation vol57 no 12 pp 3765ndash3771 2009
[5] S J Mazlouman X J Jiang A Mahanfar C Menon and R GVaughan ldquoA reconfigurable patch antenna using liquid metalembedded in a silicone substraterdquo IEEE Transactions on Anten-nas and Propagation vol 59 no 12 pp 4406ndash4412 2011
[6] M R Khan G J Hayes J-H So G Lazzi andM D Dickey ldquoAfrequency shifting liquid metal antenna with pressure respon-sivenessrdquoApplied Physics Letters vol 99 no 1 Article ID 0135012011
[7] G J Hayes J-H So A Qusba M D Dickey and G LazzildquoFlexible liquid metal alloy (EGaIn) microstrip patch antennardquoIEEE Transactions on Antennas and Propagation vol 60 no 5pp 2151ndash2156 2012
[8] A Dey R Guldiken and G Mumcu ldquoWideband frequencytunable liquid metal monopole antennardquo in Proceedings of theIEEE Antennas and Propagation Society International Sympo-sium (APSURSI rsquo13) pp 392ndash393 IEEE Orlando Fla USA July2013
[9] A M Morishita C K Y Kitamura A T Ohta and W A Shi-roma ldquoTwo-octave tunable liquid-metal monopole antennardquoElectronics Letters vol 50 no 1 pp 19ndash20 2014
[10] A M Morishita C K Y Kitamura A T Ohta and W AShiroma ldquoA liquid-metal monopole array with tunable fre-quency gain and beam steeringrdquo IEEE Antennas and WirelessPropagation Letters vol 12 no 1 pp 1388ndash1391 2013
[11] D Rodrigo L Jofre and B A Cetiner ldquoCircular beam-steeringreconfigurable antenna with liquid metal parasiticsrdquo IEEETransactions on Antennas and Propagation vol 60 no 4 pp1796ndash1802 2012
[12] Z-H Wu Y Lou J Bao and E K N Yung ldquoA circular patchfed by a switch line balun with printed L-probes for broadbandCP performancerdquo in Proceedings of the IEEE Antennas andPropagation Society International Symposium pp 1ndash4 IEEE SanDiego Calif USA July 2008
[13] J D Kraus ldquoHelical beam antennardquo Electronics vol 20 pp 109ndash111 1947
[14] S Fu Y Zhou S Fang and Y Cao ldquoDesign of low profileand variable pitch angle helical antenna for maritime satellitecommunicationsrdquo Chinese Journal of Radio Science vol 28 no1 pp 63ndash67 2013
[15] C A Balanis Antenna Theory Wiley-Interscience HobokenNJ USA 3rd edition 2005
[16] H Nakano H Takeda T Honma H Mimaki and J YamauchildquoExtremely low-profile helix radiating a circularly polarizedwaverdquo IEEE Transactions on Antennas and Propagation vol 39no 6 pp 754ndash757 1991
[17] Z Chen and Z Shen ldquoPlanar helical antenna of circular polar-izationrdquo IEEE Transactions on Antennas and Propagation vol63 no 10 pp 4315ndash4323 2015
[18] X Bai J Tang X Liang J Geng and R Jin ldquoCompact designof triple-band circularly polarized quadrifilar helix antennasrdquoIEEE Antennas and Wireless Propagation Letters vol 13 pp380ndash383 2014
[19] J Guo Y Yang Y Huang and B Sun ldquoSlot multi-arm helixantenna with simple and efficient feeding networkrdquo ElectronicsLetters vol 51 no 16 pp 1224ndash1226 2015
[20] L Liu Y Li Z Zhang and Z Feng ldquoCompact helical antennawith small ground fed by spiral-shaped microstrip linerdquo Elec-tronics Letters vol 50 no 5 pp 336ndash338 2014
[21] T L Zhang X Q Yang D L Fei and Z H Yan ldquoSingle-armhelical antenna with width of arm varying periodically for tiltedbeamrdquo Electronics Letters vol 51 no 10 pp 736ndash738 2015
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
4 International Journal of Antennas and Propagation
Frequency (GHz)302826242220181614121008
250
200
150
100
50
0
minus50
minus100
Inpu
t im
peda
nce (
Ω)
ImImIm
ReReRe
pl = 242mm pw = 26mmpl = 242mm pw = 28mmpl = 242mm pw = 30mm
(a)
Frequency (GHz)302826242220181614121008
200
150
100
50
0
minus50
minus100
Inpu
t im
peda
nce (
Ω)
ImImIm
ReReRe
pl = 22mm pw = 28mmpl = 242mm pw = 28mmpl = 262mm pw = 28mm
(b)
Figure 4 Input impedance as a function of the matching stub length and width (a) Changing 119901119908 (b) Changing 119901119897
Figure 5 Photograph of the proposed antenna
S 11
(dB)
Frequency (GHz)
0
minus5
minus10
minus15
minus20
minus25
minus30
302826242220181614121008060402
SimulatedMeasured
(a)
S 11
(dB)
0
5
minus5
minus10
minus15
minus20
minus25
minus30
03 06 09 12 15 18 21 24 27 30
Frequency (GHz)
SimulatedMeasured
(b)
Figure 6 The simulated and measured reflection coefficients (a) LHCP (b) RHCP
International Journal of Antennas and Propagation 5
80
70
60
50
40
30
20
10
0
Axi
al ra
tio (d
B)
Gai
n (d
B)
Measured ARSimulated AR
Measured gainSimulated gain
12
9
6
3
0
Frequency (GHz)302826242220181614121008060402
(a)
80
70
60
50
40
30
20
10
0
Axi
al ra
tio (d
B)
Frequency (GHz)
Measured ARSimulated AR
Measured gainSimulated gain
302826242220181614121008060402
Gai
n (d
B)
12
9
6
3
0
(b)
Figure 7 The simulated and measured axial ratio and gain (a) LHCP (b) RHCP
Table 2 Performance comparison of the state-of-the-art helical antenna
Ref StructureImpedancebandwidth|11987811| lt minus10 dB
AR bandwidth(AR lt 3 dB)
Height (1205820is the
wavelength at thecenter frequency)
Gain at center frequency (dB)
[18] Nonplanar6934217
421315
0331205820
02971205820
0291205820
45 dBi
[19] Nonplanar 923 32 0231205820
477 dBi
[20] Nonplanar 182 mdash 2961205820
13 dBi
[21] Nonplanar 128 mdash 1111205820
65 dBi
[17] Planar 54 34 0111205820
8 dBi
Our work Nonplanar356 (RHCP)36 (LHCP)(|11987811| lt minus15 dB)
265 041205820
8 dBi
Figure 9 depicts that the simulated efficiencies of the samestructure antennas vary with the frequency The conductorsare separately the aluminum the copper and the EGaIn Ascan be seen the efficiency of the EGaIn antenna is above 90within the whole working band
The simulated efficiencies of the antenna respectivelyby HFSS and CST are shown in Figure 10 It is shown thatwithin the whole working band the results keep consistentby different simulator
Table 2 summarizes the performance comparison of thestate-of-the-art helical antennas Compared to the othernonplanar helical antennas our proposed antenna clearlyexhibits the obvious advantages in terms of impedance andAR bandwidths It is seen that although the antenna in [17]retains wider impedance and AR bandwidths and has anobvious advantage than others its structure is planar Inaddition our antenna is a novel design that applied liquid
metal to design a polarization-reconfigurable helical antennaSo far the research on helical antenna based on liquid metalhas not been found yet
4 Conclusion
A novel polarization-reconfigurable conical helical antennawith liquid metal is achieved A truncated structure a var-iable pitch angle amatching stub and amechanical autorota-tion device are adopted in the proposed antennaThe circularpolarization radiation mode of the antenna can be switchedbetween the left hand and the right hand In the entire workband (1525ndash16605MHz) the gain of the antenna achieveshigher than 8 dBi and the 3 dB axial ratio (AR) bandwidthreaches 410MHz from 1340MHz to 1750MHz Experimentalresults confirm that the proposed liquid metal conical helical
6 International Journal of Antennas and Propagation
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(a)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(b)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(c)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus40
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(d)
Figure 8The simulated and measured radiation patterns (a) LHCP at 119909119900119911 plane (b) LHCP at 119910119900119911 plane (c) RHCP at 119909119900119911 plane (d) RHCPat 119910119900119911 plane
antenna can be a good candidate for circular polarization-reconfigurable antenna
Conflict of InterestsThe authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was supported jointly by the National Natural Sci-ence Foundation of China (no 61401056 and no 61571075)the Scientific Research Project of the Education Office ofLiaoning Province (no L2012171) and the Liaoning NormalUniversity Youth Project (no LS2014L003)
International Journal of Antennas and Propagation 7
Frequency (GHz)
CopperAluminum
3027242118151209060300
02
04
06
08
10
Effici
ency
()
EGaIn
Figure 9 Comparison of the efficiency among different conductors
Frequency (GHz)
HFSSCST
3027242118151209060300
00
02
04
06
08
10
Effici
ency
()
Figure 10 Comparison of the efficiency between HFSS and CST
References
[1] D Schaubert ldquoFrequency-agile polarization diverse microstripantennas and frequency scanned arraysrdquoUSUSPatent 43674741983
[2] M Kelley C Koo H McQuilken et al ldquoFrequency reconfig-urable patch antenna using liquid metal as switching mecha-nismrdquo Electronics Letters vol 49 no 22 pp 1370ndash1371 2013
[3] J-H So J Thelen A Qusba G J Hayes G Lazzi and M DDickey ldquoReversibly deformable and mechanically tunable flu-idic antennasrdquo Advanced Functional Materials vol 19 no 22pp 3632ndash3637 2009
[4] S Cheng Z Wu P Hallbjorner K Hjort and A RydbergldquoFoldable and stretchable liquid metal planar inverted coneantennardquo IEEE Transactions on Antennas and Propagation vol57 no 12 pp 3765ndash3771 2009
[5] S J Mazlouman X J Jiang A Mahanfar C Menon and R GVaughan ldquoA reconfigurable patch antenna using liquid metalembedded in a silicone substraterdquo IEEE Transactions on Anten-nas and Propagation vol 59 no 12 pp 4406ndash4412 2011
[6] M R Khan G J Hayes J-H So G Lazzi andM D Dickey ldquoAfrequency shifting liquid metal antenna with pressure respon-sivenessrdquoApplied Physics Letters vol 99 no 1 Article ID 0135012011
[7] G J Hayes J-H So A Qusba M D Dickey and G LazzildquoFlexible liquid metal alloy (EGaIn) microstrip patch antennardquoIEEE Transactions on Antennas and Propagation vol 60 no 5pp 2151ndash2156 2012
[8] A Dey R Guldiken and G Mumcu ldquoWideband frequencytunable liquid metal monopole antennardquo in Proceedings of theIEEE Antennas and Propagation Society International Sympo-sium (APSURSI rsquo13) pp 392ndash393 IEEE Orlando Fla USA July2013
[9] A M Morishita C K Y Kitamura A T Ohta and W A Shi-roma ldquoTwo-octave tunable liquid-metal monopole antennardquoElectronics Letters vol 50 no 1 pp 19ndash20 2014
[10] A M Morishita C K Y Kitamura A T Ohta and W AShiroma ldquoA liquid-metal monopole array with tunable fre-quency gain and beam steeringrdquo IEEE Antennas and WirelessPropagation Letters vol 12 no 1 pp 1388ndash1391 2013
[11] D Rodrigo L Jofre and B A Cetiner ldquoCircular beam-steeringreconfigurable antenna with liquid metal parasiticsrdquo IEEETransactions on Antennas and Propagation vol 60 no 4 pp1796ndash1802 2012
[12] Z-H Wu Y Lou J Bao and E K N Yung ldquoA circular patchfed by a switch line balun with printed L-probes for broadbandCP performancerdquo in Proceedings of the IEEE Antennas andPropagation Society International Symposium pp 1ndash4 IEEE SanDiego Calif USA July 2008
[13] J D Kraus ldquoHelical beam antennardquo Electronics vol 20 pp 109ndash111 1947
[14] S Fu Y Zhou S Fang and Y Cao ldquoDesign of low profileand variable pitch angle helical antenna for maritime satellitecommunicationsrdquo Chinese Journal of Radio Science vol 28 no1 pp 63ndash67 2013
[15] C A Balanis Antenna Theory Wiley-Interscience HobokenNJ USA 3rd edition 2005
[16] H Nakano H Takeda T Honma H Mimaki and J YamauchildquoExtremely low-profile helix radiating a circularly polarizedwaverdquo IEEE Transactions on Antennas and Propagation vol 39no 6 pp 754ndash757 1991
[17] Z Chen and Z Shen ldquoPlanar helical antenna of circular polar-izationrdquo IEEE Transactions on Antennas and Propagation vol63 no 10 pp 4315ndash4323 2015
[18] X Bai J Tang X Liang J Geng and R Jin ldquoCompact designof triple-band circularly polarized quadrifilar helix antennasrdquoIEEE Antennas and Wireless Propagation Letters vol 13 pp380ndash383 2014
[19] J Guo Y Yang Y Huang and B Sun ldquoSlot multi-arm helixantenna with simple and efficient feeding networkrdquo ElectronicsLetters vol 51 no 16 pp 1224ndash1226 2015
[20] L Liu Y Li Z Zhang and Z Feng ldquoCompact helical antennawith small ground fed by spiral-shaped microstrip linerdquo Elec-tronics Letters vol 50 no 5 pp 336ndash338 2014
[21] T L Zhang X Q Yang D L Fei and Z H Yan ldquoSingle-armhelical antenna with width of arm varying periodically for tiltedbeamrdquo Electronics Letters vol 51 no 10 pp 736ndash738 2015
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
International Journal of Antennas and Propagation 5
80
70
60
50
40
30
20
10
0
Axi
al ra
tio (d
B)
Gai
n (d
B)
Measured ARSimulated AR
Measured gainSimulated gain
12
9
6
3
0
Frequency (GHz)302826242220181614121008060402
(a)
80
70
60
50
40
30
20
10
0
Axi
al ra
tio (d
B)
Frequency (GHz)
Measured ARSimulated AR
Measured gainSimulated gain
302826242220181614121008060402
Gai
n (d
B)
12
9
6
3
0
(b)
Figure 7 The simulated and measured axial ratio and gain (a) LHCP (b) RHCP
Table 2 Performance comparison of the state-of-the-art helical antenna
Ref StructureImpedancebandwidth|11987811| lt minus10 dB
AR bandwidth(AR lt 3 dB)
Height (1205820is the
wavelength at thecenter frequency)
Gain at center frequency (dB)
[18] Nonplanar6934217
421315
0331205820
02971205820
0291205820
45 dBi
[19] Nonplanar 923 32 0231205820
477 dBi
[20] Nonplanar 182 mdash 2961205820
13 dBi
[21] Nonplanar 128 mdash 1111205820
65 dBi
[17] Planar 54 34 0111205820
8 dBi
Our work Nonplanar356 (RHCP)36 (LHCP)(|11987811| lt minus15 dB)
265 041205820
8 dBi
Figure 9 depicts that the simulated efficiencies of the samestructure antennas vary with the frequency The conductorsare separately the aluminum the copper and the EGaIn Ascan be seen the efficiency of the EGaIn antenna is above 90within the whole working band
The simulated efficiencies of the antenna respectivelyby HFSS and CST are shown in Figure 10 It is shown thatwithin the whole working band the results keep consistentby different simulator
Table 2 summarizes the performance comparison of thestate-of-the-art helical antennas Compared to the othernonplanar helical antennas our proposed antenna clearlyexhibits the obvious advantages in terms of impedance andAR bandwidths It is seen that although the antenna in [17]retains wider impedance and AR bandwidths and has anobvious advantage than others its structure is planar Inaddition our antenna is a novel design that applied liquid
metal to design a polarization-reconfigurable helical antennaSo far the research on helical antenna based on liquid metalhas not been found yet
4 Conclusion
A novel polarization-reconfigurable conical helical antennawith liquid metal is achieved A truncated structure a var-iable pitch angle amatching stub and amechanical autorota-tion device are adopted in the proposed antennaThe circularpolarization radiation mode of the antenna can be switchedbetween the left hand and the right hand In the entire workband (1525ndash16605MHz) the gain of the antenna achieveshigher than 8 dBi and the 3 dB axial ratio (AR) bandwidthreaches 410MHz from 1340MHz to 1750MHz Experimentalresults confirm that the proposed liquid metal conical helical
6 International Journal of Antennas and Propagation
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(a)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(b)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(c)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus40
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(d)
Figure 8The simulated and measured radiation patterns (a) LHCP at 119909119900119911 plane (b) LHCP at 119910119900119911 plane (c) RHCP at 119909119900119911 plane (d) RHCPat 119910119900119911 plane
antenna can be a good candidate for circular polarization-reconfigurable antenna
Conflict of InterestsThe authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was supported jointly by the National Natural Sci-ence Foundation of China (no 61401056 and no 61571075)the Scientific Research Project of the Education Office ofLiaoning Province (no L2012171) and the Liaoning NormalUniversity Youth Project (no LS2014L003)
International Journal of Antennas and Propagation 7
Frequency (GHz)
CopperAluminum
3027242118151209060300
02
04
06
08
10
Effici
ency
()
EGaIn
Figure 9 Comparison of the efficiency among different conductors
Frequency (GHz)
HFSSCST
3027242118151209060300
00
02
04
06
08
10
Effici
ency
()
Figure 10 Comparison of the efficiency between HFSS and CST
References
[1] D Schaubert ldquoFrequency-agile polarization diverse microstripantennas and frequency scanned arraysrdquoUSUSPatent 43674741983
[2] M Kelley C Koo H McQuilken et al ldquoFrequency reconfig-urable patch antenna using liquid metal as switching mecha-nismrdquo Electronics Letters vol 49 no 22 pp 1370ndash1371 2013
[3] J-H So J Thelen A Qusba G J Hayes G Lazzi and M DDickey ldquoReversibly deformable and mechanically tunable flu-idic antennasrdquo Advanced Functional Materials vol 19 no 22pp 3632ndash3637 2009
[4] S Cheng Z Wu P Hallbjorner K Hjort and A RydbergldquoFoldable and stretchable liquid metal planar inverted coneantennardquo IEEE Transactions on Antennas and Propagation vol57 no 12 pp 3765ndash3771 2009
[5] S J Mazlouman X J Jiang A Mahanfar C Menon and R GVaughan ldquoA reconfigurable patch antenna using liquid metalembedded in a silicone substraterdquo IEEE Transactions on Anten-nas and Propagation vol 59 no 12 pp 4406ndash4412 2011
[6] M R Khan G J Hayes J-H So G Lazzi andM D Dickey ldquoAfrequency shifting liquid metal antenna with pressure respon-sivenessrdquoApplied Physics Letters vol 99 no 1 Article ID 0135012011
[7] G J Hayes J-H So A Qusba M D Dickey and G LazzildquoFlexible liquid metal alloy (EGaIn) microstrip patch antennardquoIEEE Transactions on Antennas and Propagation vol 60 no 5pp 2151ndash2156 2012
[8] A Dey R Guldiken and G Mumcu ldquoWideband frequencytunable liquid metal monopole antennardquo in Proceedings of theIEEE Antennas and Propagation Society International Sympo-sium (APSURSI rsquo13) pp 392ndash393 IEEE Orlando Fla USA July2013
[9] A M Morishita C K Y Kitamura A T Ohta and W A Shi-roma ldquoTwo-octave tunable liquid-metal monopole antennardquoElectronics Letters vol 50 no 1 pp 19ndash20 2014
[10] A M Morishita C K Y Kitamura A T Ohta and W AShiroma ldquoA liquid-metal monopole array with tunable fre-quency gain and beam steeringrdquo IEEE Antennas and WirelessPropagation Letters vol 12 no 1 pp 1388ndash1391 2013
[11] D Rodrigo L Jofre and B A Cetiner ldquoCircular beam-steeringreconfigurable antenna with liquid metal parasiticsrdquo IEEETransactions on Antennas and Propagation vol 60 no 4 pp1796ndash1802 2012
[12] Z-H Wu Y Lou J Bao and E K N Yung ldquoA circular patchfed by a switch line balun with printed L-probes for broadbandCP performancerdquo in Proceedings of the IEEE Antennas andPropagation Society International Symposium pp 1ndash4 IEEE SanDiego Calif USA July 2008
[13] J D Kraus ldquoHelical beam antennardquo Electronics vol 20 pp 109ndash111 1947
[14] S Fu Y Zhou S Fang and Y Cao ldquoDesign of low profileand variable pitch angle helical antenna for maritime satellitecommunicationsrdquo Chinese Journal of Radio Science vol 28 no1 pp 63ndash67 2013
[15] C A Balanis Antenna Theory Wiley-Interscience HobokenNJ USA 3rd edition 2005
[16] H Nakano H Takeda T Honma H Mimaki and J YamauchildquoExtremely low-profile helix radiating a circularly polarizedwaverdquo IEEE Transactions on Antennas and Propagation vol 39no 6 pp 754ndash757 1991
[17] Z Chen and Z Shen ldquoPlanar helical antenna of circular polar-izationrdquo IEEE Transactions on Antennas and Propagation vol63 no 10 pp 4315ndash4323 2015
[18] X Bai J Tang X Liang J Geng and R Jin ldquoCompact designof triple-band circularly polarized quadrifilar helix antennasrdquoIEEE Antennas and Wireless Propagation Letters vol 13 pp380ndash383 2014
[19] J Guo Y Yang Y Huang and B Sun ldquoSlot multi-arm helixantenna with simple and efficient feeding networkrdquo ElectronicsLetters vol 51 no 16 pp 1224ndash1226 2015
[20] L Liu Y Li Z Zhang and Z Feng ldquoCompact helical antennawith small ground fed by spiral-shaped microstrip linerdquo Elec-tronics Letters vol 50 no 5 pp 336ndash338 2014
[21] T L Zhang X Q Yang D L Fei and Z H Yan ldquoSingle-armhelical antenna with width of arm varying periodically for tiltedbeamrdquo Electronics Letters vol 51 no 10 pp 736ndash738 2015
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
6 International Journal of Antennas and Propagation
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(a)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(b)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(c)
020
40
60
80
100
120
140
160180
200
220
240
260
280
300
320
34010
0
minus10
minus20
minus30
minus40
minus30
minus20
minus10
0
10
Simulated (RHCP)Measured (RHCP)
Simulated (LHCP)Measured (LHCP)
(d)
Figure 8The simulated and measured radiation patterns (a) LHCP at 119909119900119911 plane (b) LHCP at 119910119900119911 plane (c) RHCP at 119909119900119911 plane (d) RHCPat 119910119900119911 plane
antenna can be a good candidate for circular polarization-reconfigurable antenna
Conflict of InterestsThe authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was supported jointly by the National Natural Sci-ence Foundation of China (no 61401056 and no 61571075)the Scientific Research Project of the Education Office ofLiaoning Province (no L2012171) and the Liaoning NormalUniversity Youth Project (no LS2014L003)
International Journal of Antennas and Propagation 7
Frequency (GHz)
CopperAluminum
3027242118151209060300
02
04
06
08
10
Effici
ency
()
EGaIn
Figure 9 Comparison of the efficiency among different conductors
Frequency (GHz)
HFSSCST
3027242118151209060300
00
02
04
06
08
10
Effici
ency
()
Figure 10 Comparison of the efficiency between HFSS and CST
References
[1] D Schaubert ldquoFrequency-agile polarization diverse microstripantennas and frequency scanned arraysrdquoUSUSPatent 43674741983
[2] M Kelley C Koo H McQuilken et al ldquoFrequency reconfig-urable patch antenna using liquid metal as switching mecha-nismrdquo Electronics Letters vol 49 no 22 pp 1370ndash1371 2013
[3] J-H So J Thelen A Qusba G J Hayes G Lazzi and M DDickey ldquoReversibly deformable and mechanically tunable flu-idic antennasrdquo Advanced Functional Materials vol 19 no 22pp 3632ndash3637 2009
[4] S Cheng Z Wu P Hallbjorner K Hjort and A RydbergldquoFoldable and stretchable liquid metal planar inverted coneantennardquo IEEE Transactions on Antennas and Propagation vol57 no 12 pp 3765ndash3771 2009
[5] S J Mazlouman X J Jiang A Mahanfar C Menon and R GVaughan ldquoA reconfigurable patch antenna using liquid metalembedded in a silicone substraterdquo IEEE Transactions on Anten-nas and Propagation vol 59 no 12 pp 4406ndash4412 2011
[6] M R Khan G J Hayes J-H So G Lazzi andM D Dickey ldquoAfrequency shifting liquid metal antenna with pressure respon-sivenessrdquoApplied Physics Letters vol 99 no 1 Article ID 0135012011
[7] G J Hayes J-H So A Qusba M D Dickey and G LazzildquoFlexible liquid metal alloy (EGaIn) microstrip patch antennardquoIEEE Transactions on Antennas and Propagation vol 60 no 5pp 2151ndash2156 2012
[8] A Dey R Guldiken and G Mumcu ldquoWideband frequencytunable liquid metal monopole antennardquo in Proceedings of theIEEE Antennas and Propagation Society International Sympo-sium (APSURSI rsquo13) pp 392ndash393 IEEE Orlando Fla USA July2013
[9] A M Morishita C K Y Kitamura A T Ohta and W A Shi-roma ldquoTwo-octave tunable liquid-metal monopole antennardquoElectronics Letters vol 50 no 1 pp 19ndash20 2014
[10] A M Morishita C K Y Kitamura A T Ohta and W AShiroma ldquoA liquid-metal monopole array with tunable fre-quency gain and beam steeringrdquo IEEE Antennas and WirelessPropagation Letters vol 12 no 1 pp 1388ndash1391 2013
[11] D Rodrigo L Jofre and B A Cetiner ldquoCircular beam-steeringreconfigurable antenna with liquid metal parasiticsrdquo IEEETransactions on Antennas and Propagation vol 60 no 4 pp1796ndash1802 2012
[12] Z-H Wu Y Lou J Bao and E K N Yung ldquoA circular patchfed by a switch line balun with printed L-probes for broadbandCP performancerdquo in Proceedings of the IEEE Antennas andPropagation Society International Symposium pp 1ndash4 IEEE SanDiego Calif USA July 2008
[13] J D Kraus ldquoHelical beam antennardquo Electronics vol 20 pp 109ndash111 1947
[14] S Fu Y Zhou S Fang and Y Cao ldquoDesign of low profileand variable pitch angle helical antenna for maritime satellitecommunicationsrdquo Chinese Journal of Radio Science vol 28 no1 pp 63ndash67 2013
[15] C A Balanis Antenna Theory Wiley-Interscience HobokenNJ USA 3rd edition 2005
[16] H Nakano H Takeda T Honma H Mimaki and J YamauchildquoExtremely low-profile helix radiating a circularly polarizedwaverdquo IEEE Transactions on Antennas and Propagation vol 39no 6 pp 754ndash757 1991
[17] Z Chen and Z Shen ldquoPlanar helical antenna of circular polar-izationrdquo IEEE Transactions on Antennas and Propagation vol63 no 10 pp 4315ndash4323 2015
[18] X Bai J Tang X Liang J Geng and R Jin ldquoCompact designof triple-band circularly polarized quadrifilar helix antennasrdquoIEEE Antennas and Wireless Propagation Letters vol 13 pp380ndash383 2014
[19] J Guo Y Yang Y Huang and B Sun ldquoSlot multi-arm helixantenna with simple and efficient feeding networkrdquo ElectronicsLetters vol 51 no 16 pp 1224ndash1226 2015
[20] L Liu Y Li Z Zhang and Z Feng ldquoCompact helical antennawith small ground fed by spiral-shaped microstrip linerdquo Elec-tronics Letters vol 50 no 5 pp 336ndash338 2014
[21] T L Zhang X Q Yang D L Fei and Z H Yan ldquoSingle-armhelical antenna with width of arm varying periodically for tiltedbeamrdquo Electronics Letters vol 51 no 10 pp 736ndash738 2015
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
International Journal of Antennas and Propagation 7
Frequency (GHz)
CopperAluminum
3027242118151209060300
02
04
06
08
10
Effici
ency
()
EGaIn
Figure 9 Comparison of the efficiency among different conductors
Frequency (GHz)
HFSSCST
3027242118151209060300
00
02
04
06
08
10
Effici
ency
()
Figure 10 Comparison of the efficiency between HFSS and CST
References
[1] D Schaubert ldquoFrequency-agile polarization diverse microstripantennas and frequency scanned arraysrdquoUSUSPatent 43674741983
[2] M Kelley C Koo H McQuilken et al ldquoFrequency reconfig-urable patch antenna using liquid metal as switching mecha-nismrdquo Electronics Letters vol 49 no 22 pp 1370ndash1371 2013
[3] J-H So J Thelen A Qusba G J Hayes G Lazzi and M DDickey ldquoReversibly deformable and mechanically tunable flu-idic antennasrdquo Advanced Functional Materials vol 19 no 22pp 3632ndash3637 2009
[4] S Cheng Z Wu P Hallbjorner K Hjort and A RydbergldquoFoldable and stretchable liquid metal planar inverted coneantennardquo IEEE Transactions on Antennas and Propagation vol57 no 12 pp 3765ndash3771 2009
[5] S J Mazlouman X J Jiang A Mahanfar C Menon and R GVaughan ldquoA reconfigurable patch antenna using liquid metalembedded in a silicone substraterdquo IEEE Transactions on Anten-nas and Propagation vol 59 no 12 pp 4406ndash4412 2011
[6] M R Khan G J Hayes J-H So G Lazzi andM D Dickey ldquoAfrequency shifting liquid metal antenna with pressure respon-sivenessrdquoApplied Physics Letters vol 99 no 1 Article ID 0135012011
[7] G J Hayes J-H So A Qusba M D Dickey and G LazzildquoFlexible liquid metal alloy (EGaIn) microstrip patch antennardquoIEEE Transactions on Antennas and Propagation vol 60 no 5pp 2151ndash2156 2012
[8] A Dey R Guldiken and G Mumcu ldquoWideband frequencytunable liquid metal monopole antennardquo in Proceedings of theIEEE Antennas and Propagation Society International Sympo-sium (APSURSI rsquo13) pp 392ndash393 IEEE Orlando Fla USA July2013
[9] A M Morishita C K Y Kitamura A T Ohta and W A Shi-roma ldquoTwo-octave tunable liquid-metal monopole antennardquoElectronics Letters vol 50 no 1 pp 19ndash20 2014
[10] A M Morishita C K Y Kitamura A T Ohta and W AShiroma ldquoA liquid-metal monopole array with tunable fre-quency gain and beam steeringrdquo IEEE Antennas and WirelessPropagation Letters vol 12 no 1 pp 1388ndash1391 2013
[11] D Rodrigo L Jofre and B A Cetiner ldquoCircular beam-steeringreconfigurable antenna with liquid metal parasiticsrdquo IEEETransactions on Antennas and Propagation vol 60 no 4 pp1796ndash1802 2012
[12] Z-H Wu Y Lou J Bao and E K N Yung ldquoA circular patchfed by a switch line balun with printed L-probes for broadbandCP performancerdquo in Proceedings of the IEEE Antennas andPropagation Society International Symposium pp 1ndash4 IEEE SanDiego Calif USA July 2008
[13] J D Kraus ldquoHelical beam antennardquo Electronics vol 20 pp 109ndash111 1947
[14] S Fu Y Zhou S Fang and Y Cao ldquoDesign of low profileand variable pitch angle helical antenna for maritime satellitecommunicationsrdquo Chinese Journal of Radio Science vol 28 no1 pp 63ndash67 2013
[15] C A Balanis Antenna Theory Wiley-Interscience HobokenNJ USA 3rd edition 2005
[16] H Nakano H Takeda T Honma H Mimaki and J YamauchildquoExtremely low-profile helix radiating a circularly polarizedwaverdquo IEEE Transactions on Antennas and Propagation vol 39no 6 pp 754ndash757 1991
[17] Z Chen and Z Shen ldquoPlanar helical antenna of circular polar-izationrdquo IEEE Transactions on Antennas and Propagation vol63 no 10 pp 4315ndash4323 2015
[18] X Bai J Tang X Liang J Geng and R Jin ldquoCompact designof triple-band circularly polarized quadrifilar helix antennasrdquoIEEE Antennas and Wireless Propagation Letters vol 13 pp380ndash383 2014
[19] J Guo Y Yang Y Huang and B Sun ldquoSlot multi-arm helixantenna with simple and efficient feeding networkrdquo ElectronicsLetters vol 51 no 16 pp 1224ndash1226 2015
[20] L Liu Y Li Z Zhang and Z Feng ldquoCompact helical antennawith small ground fed by spiral-shaped microstrip linerdquo Elec-tronics Letters vol 50 no 5 pp 336ndash338 2014
[21] T L Zhang X Q Yang D L Fei and Z H Yan ldquoSingle-armhelical antenna with width of arm varying periodically for tiltedbeamrdquo Electronics Letters vol 51 no 10 pp 736ndash738 2015
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
![Research Article A Planar Reconfigurable Radiation Pattern ...downloads.hindawi.com/journals/ijap/2014/593259.pdf · pattern antenna based on the conventional Yagi antenna [ ], an](https://static.fdocuments.in/doc/165x107/6041bcb849cb3d371875f647/research-article-a-planar-reconfigurable-radiation-pattern-pattern-antenna-based.jpg)
