GJCAT_2012_0129

ISSN: 2249-1945

Ravi Kishore et al, GJCAT, Vol 2 (1), 2012, 952-956

952

1S.Nagarani,

1Ch.Ravi Kishore,

1A.Prudhvi Raj

2T.V.Rama Krishna, 2K.Sarat Kumar, 3M.S.G Prasad, 3B.T.P. Madhav

1Project Students, Department of ECE, K L University, Guntur DT, AP, India 2Professor and Associate DEAN-R&D, Department of ECE, KL University

3Associative Professor LCRC-R&D, Department of ECE, K L University, Guntur DT, AP, India

Abstract: There is lot of demand for ultra high frequency

broadband antennas in wireless communications due to

requirements of more bandwidths. Sinuous antenna is a

type of log- periodic spiral antennas which is having

spectral efficiency over other patch antennas. Using the

commercial Ansoft HFSS software 2-petals and 4-petals

sinuous antennas were designed and simulated. The

operating frequency range is 4 to 10 GHz. Return loss,

input impedance, gain, radiation patterns, axial ratio,

polarization and directivity are simulated and presented in

this paper.

Keywords: sinuous, broadband, return loss, polarization.

1. Introduction

Log-periodic planar sinuous antennas come

under the category of frequency independent

antennas and they are mostly used in the wideband

applications[1]. The characteristics of logarithmically

periodic antenna structures repeat periodically with

the logarithm of frequency. Sinuous antenna is the

special type of spiral antenna in the microstrip

antennas which is a low profile antenna that is having

number of advantages over other antennas. It is light

weight, inexpensive and electronics like LNAs and SSPAs can be integrated with these antennas quite easily. It can be integrated with circuit elements and

can be designed for dual or multi frequency

operations. The usage of wideband antennas are

increasing due to its extremely fine time and range

solution even through lossy, opaque media, large

processing gains, immunity from multipath[1,2].

Sinuous antenna is having some specific

characteristics like dual polarization, broadband,

small size, and low directivity. Sinuous antennas can

be used in defence industry for sensing purpose, in

military aircrafts, in RADAR warning receivers, in

general ESM applications, feed for Square Kilometre

Array(SKA). Reliable antenna patterns can be

obtained over the given band by the designed sinuous

antennas[3].

2. Antenna Geometry

The log periodic structure is considered to

be composed of "cells", with each cell being a scaled

version of its predecessor. The "cells" of the sinuous

structure were generated from the sinuous curve

which is defined by the equation provided by R. H.

Du Hamel[5].

Where, p : Angular width of arc(pth cell) c : Number of Cells/Resonators

r, : Polar coordinates of the curve

Active resonant Region r = /4(+) Where , in radians 2.1 Design Specifications

4-Petals Sinuous antenna

The dimensions of the 4-petal sinuous

antenna are shown in the Table (1). The proposed

antenna is simulated between the solution frequencies

4 to 10 GHz.

S.no Input parameters Dimensions

1. Desired frequency range 4.0 to 10.4 GHz

2. No. of points along arm 200

3. No. of cells 8

4. Alpha 45 deg

5. Growth rate 0.79 cm

6. Outer radius 1.99 cm

7. Delta 22.5 deg

8. No. of petals 4

9. Port extension Height 0.1 cm

Table (1) 4-petal sinuous antenna dimensions

ISSN: 2249-1945


953

2-Petals Sinuous antenna

The dimensions of the 2-petal sinuous antenna

are shown in the Table (2). The proposed antenna is

simulated between the solution frequencies 4 to 10

GHz.

S.no Input parameters Dimensions

1. Desired frequency range 3.95 to 10.15

GHz

2. No. of points along arm 200

3. No. of cells 8

4. Alpha 45 deg

5. Growth rate 0.79 cm

6. Outer radius 1.99 cm

7. Delta 22.5 deg

8. No. of petals 2

9. Port extension Height 0.1 cm

Table (2) 2-petal sinuous antenna dimensions

Figures (1) and (2) show 4-petals and 2-petals

broadband sinuous antennas respectively designed in

HFSS for the above specifications.

Figure(1) 4-petals sinuous antenna model

Figure(2) 2-petals sinuous antenna model

3. Results and Discussion

Return loss or VSWR is good when the

curve has a deep and wide dip, which shows the

antenna with good bandwidth. If the Return loss is -

3dB then the antenna absorbs 50% of the signal and

50% is reflect back. The proposed antennas are

showing acceptable return loss over the entire range

in the figures (3) and (4). For 4-petals sinuous

antenna the return loss of -17.66, - 26.21, -37.20, and

-25.93dB is obtained at 4.12, 4.35, 5.86 and 7.85

GHz respectively. For 2-petals sinuous antenna the

return loss of -14.79, - 30.75 and -29.57dB is

obtained at 4.81, 6.18 and 8.17 GHz respectively

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00Freq [GHz]

-40.00

-35.00

-30.00

-25.00

-20.00

-15.00

-10.00

dB

(S

t(1

,1)

)

Ansoft Corporation Sinuous_Antenna_ADKv1Return Loss

m1

m2

m3

m4

Curve Info

dB(St(1,1))

Setup1 : Sw eep1

Name X Y

m1 4.1286 -17.6612

m2 4.3538 -26.2146

m3 5.8653 -37.2010

m4 7.8593 -25.9370

Figure (3) Return loss for 4-petals

3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00Freq [GHz]

-35.00

-30.00

-25.00

-20.00

-15.00

-10.00

-5.00

0.00

dB

(S

t(

1,1

))

Ansoft Corporation Sinuous_Antenna_ADKv1Return Loss

m1

m2m3

Curve Info

dB(St(1,1))

Setup1 : Sw eep1

Name X Y

m1 4.8123 -14.7948

m2 6.1887 -30.7518

m3 8.1733 -29.5774

Figure (4) Return loss for 2-petals

ISSN: 2249-1945


954

Figures (5) and (6) show the input

impedance smith chart for the proposed models.

Maximum power will be transferred if the impedance

of the antenna is matched to those of the load. Rms of

0.0907 and bandwidth of 4 is attained from the 4-

petals sinuous antenna simulated results and rms of

0.2572 and bandwidth of 3.98 is attained from the 2-

petals sinuous antenna simulated results.

5.002.001.000.500.20

5.00

-5.00

2.00

-2.00

1.00

-1.00

0.50

-0.50

0.20

-0.20

0.00-0.000

10

20

30

40

5060

708090100

110120

130

140

150

160

170

180

-170

-160

-150

-140

-130-120

-110-100 -90 -80

-70-60

-50

-40

-30

-20

-10

Ansoft Corporation Sinuous_Antenna_ADKv1Input Impedance

Curve Info rms

St(1,1))

Setup1 : Sw eep10.0907

Figure (5) Smith chart for 4-petals

5.002.001.000.500.20

5.00

-5.00

2.00

-2.00

1.00

-1.00

0.50

-0.50

0.20

-0.20

0.00-0.000

10

20

30

40

5060

708090100

110120

130

140

150

160

170

180

-170

-160

-150

-140

-130-120

-110-100 -90 -80

-70-60

-50

-40

-30

-20

-10

Ansoft Corporation Sinuous_Antenna_ADKv1Input Impedance

Curve Info rms

St(1,1))

Setup1 : Sw eep10.2572

Figure (6) Smith chart for 2-petals

Gain is always related to the main lobe and

it is expressed in dBi or dBd. Figures (6) and (7)

show the gain of RHCP 0f 4-petals and 2-petals

sinuous antennas respectively and figure (8) and (9)

show gain of LHCP for the same in 3D view.

Figure (6) Gain RHCP for 4-petals

Figure (7) Gain RHCP for 2-petals

Figure (8) Gain LHCP for 4-petals

Figure (9) Gain LHCP for 2-petals

The polarization of an antenna is the

orientation of the electric field (E-plane) of the radio

wave with respect to the earth surface and is

determined by the physical structure of the antenna

and by its orientation. Polarization is the sum of the

E-plane orientation over time projected on to an

imaginary plane perpendicular to the direction of

motion of the radio wave. Figure (10) and (11) show

the polarization of the 4-petals and 2-petals sinuous

antennas in RHCP respectively and figure (12) and

(13) in LHCP.

ISSN: 2249-1945


955

Figure (10) Polarization RHCP for 4-petals

Figure (11) Polarization RHCP for 2-petals

Figure (12) Polarization LHCP for 4-petals

Figure (13) Polarization LHCP for 2-petals

The axial ratio describes the electromagnetic

radiation with elliptical or circular polarization. The

axial ratio is the ratio of the magnitudes of the major

and minor axis defined by the electric field vector.

Figure (14) and (15) show the axial ratio for the 4-

petals and 2-petals sinuous antennas in 3D.

Figure (14) Axial ratio for 4-petals

Figure (15) Axial ratio for 2-petals

4. Conclusion

The objective was achieved by designing 4-

petals and 2-petals broadband sinuous antennas. The

proposed antennas were simulated and these are

giving good results for entire wide band. The

return loss of 4-petal sinuous antenna is better than 2-

petal sinuous antenna. Remaining parameters almost

same for both. Parameters of these antennas are

tabulated below.

S.no parameter 4-petals

sinuous

2-petals

sinuous

1. Wide band gain 3.867 dB 3.654dB

2. Peak gain 4.833 dB 4.567 dB

3. Peak directivity 4.773 dB 4.522 dB

4. Radiation

efficiency

1.265 1.262

5. Input impedance 0.0907 rms 0.2572 rms

Table (3) comparison of two antennas

ISSN: 2249-1945


956

One of the advantages of these models is cost

effectiveness.

5. Acknowledgements

The authors like to express their thanks to the

management of K L University and the department of

ECE for their encouragement and support during this

work. 6. References [1]. Emily McMilin and Doug Henke, A Low-Cost Directional Log Periodic Log Spiral Antenna, IEEE, 2010. [2]. G. Cortes-Medellin, Novel non planar ultra wide band Quasi Self-Complementary antenna," in Antennas and Propagation

Society International Symposium, 2007 IEEE, pp. 5733{5736,

June 2007.

[3]. V. H. Rumsey, Frequency Independent Antennas. New York:

Academic Press, 1966.

[4]. R. Olsson, P.-S. Kildal, and S. Weinreb, The Eleven antenna: a compact low-profile decade bandwidth dual polarized feed for

reflector antennas," Antennas and Propagation, IEEE Transactions

on, vol. 54, pp. 368{375, Feb. 2006.

[5]. M.J. Ammann and Z.N. Chen, Wideband Monopole Antennas for Multi-band Wireless Systems, IEEE Antennas and Propagation Magazine, 45 (2003), 146150. [6]. R Carrel, The design of the log-periodic dipole antenna, IRE Int. Conv. Rec., 9, pp. 6175, 1961. [7]. P.S. Hall, Multi octave bandwidth log-periodic microstrip antenna array, IEEE Proc., vol.133, Part H, pp127-136, April 1986.

[8]. Runa kumari and S K Behera, Log Periodic Dielectric Resonator Antenna for Broadband Applications, International Symposium on Devices MEMS, Intelligent Systems &

Communication (ISDMISC) 2011

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