A Dual-Polarized Planar-Array Antenna for S-Band and X-Band Airborne Applications-5aa

8/20/2019 A Dual-Polarized Planar-Array Antenna for S-Band and X-Band Airborne Applications-5aa

1/9

A Dual-Polarized Planar-Array Antenna for

S-Band and X-Band

Airborne

Applications

S

H

Y R

2

, a K C

1

Department of Electrical and Computer Engineering, Texas A M University

College Station, TX 77843-3128, USA

Tel: +1 (979) 845-5285; E-mail: [email protected]

21ntelligent Automation, Inc.

Rockville, MD 20855, USA

Abstract

A new dual-frequency dual-polarized array antenna for airborne applications is presented in this paper. Two planar arrays

with thin substrates (RIT Ouroid 5880 substrate, with

e;

= 2.2 and a thickness of 0.13 mm) are integrated to provide

simultaneous operation at S band (3 GHz) and X band (10 GHz). Each 3 GHz antenna element is a large rectangular ring

resonator antenna, and has a 9.5 dBi gain that is about 3 dB higher than the gain of an ordinary ring antenna. The 10 GHz

antenna elements are circular patches. They are combined to form the array with a gain of 18.3 dBi, using a series-fed

structure to save the space of the feeding line network. The ultra-thin array can be easily placed on an aircraft's fuselage, due

to its lightweight and conformal structure. It will be useful for wireless communication, radar, remote sensing, and surveillance

applications.

Keywords: Antenna arrays; microstrip arrays; microwave antenna arrays; aircraft antennas; planar arrays; polarization

1. Introduction

M

odern wireless communication systems demand low-profile,

lightweight, and relatively inexpensive antennas [1]. There

has been increasing interest in the development of dual-polarized

antennas/arrays, due to many advantages in performance improve

ment for wireless communication and radar systems. Dual

polarization avoids the requirement

of

precise alignment needed in

single-polarized systems. Dual-polarized operation can also pro

vide more information for radar systems, can increase the isolation

between the transmitting and receiving signals

of

transceivers and

transponders, and can double the capacity of communication sys

tems by means of frequency reuse [2, 3]. In simultaneous transmit

ting-receiving applications, dual-polarized antennas with two-port

connections offer an alternative to the commonly used bulky

circulator, or separate transmitting and receiving antennas. Further

more, dual-polarized antennas can provide polarization diversity,

which prevents the system's performance degradation due to multi

path fading in complex propagation environments [4]. Compared

with space diversity, the polarization-diversity technique has the

advantage of reducing the number and size of the antenna elements

in the system.

To create dual polarization, the antenna element has to be fed

at two orthogonal points or edges, such that two degenerate reso

nant modes can be excited for the orthogonal polarizations, i.e.,

vertical and horizontal polarizations. Design techniques of dual

polarized antennas can be classified into three main categories. The

first is to make an orthogonal arrangement

of

the radiation ele-

ments for two polarizations [5, 6]. The second is to properly

choose stacked structures of the radiating elements [7, 8]. The third

is to use special feeding techniques [9, 10]. In general, symmetric

structures tend to give better dual-polarization performance. At

higher frequencies, a dielectric-resonator antenna can be used to

reduce the metallic loss of the patch [11].

The dual-polarized antenna elements can be assembled to

construct a high-gain array. Although many dual-polarized anten

nas have been proposed, not all of them are good candidates for

array design, due to their complex structures and feeding-line net

works. Many of them are bulky and heavy, and not suitable for air

borne applications. On the other hand, isolation is one

of

the

important parameters to be considered in dual-polarized array

design. Most reported dual-polarized arrays achieve at least 20 dB

isolation [12-15]. To minimize the coupling between the feed-line

networks, a proximity/aperture-coupling structure can be applied to

prevent radiation due to the microstrip line and radiator from

degrading the polarization performance. The multilayer structure

can also be used to enhance the isolation, in which isolations of

better than 20-30 dB can be obtained with more-complicated struc

tures. However, most dual-polarized antenna designs will result in

a bulky array that is not suitable for use in aircraft, airships, or

unmanned aerial vehicles (DAVs).

In many airborne applications, an array antenna should have

good isolation, high efficiency, and ease of integration with the

aerial vehicle. A simple feeding-line network with lower loss and

high isolation is generally desired. Microstrip series-fed arrays

70

ISSN

1045-9243120091 25

©2009IEEE

IAa M

Vol. 51, No.4, August 2009

AlultIXDoM1a1UfIX Ra


2/9

have been shown to have a structure that enhances the antenna's

efficiency [1]. This is because the array feeding-line length is

significantly reduced, compared to the conventional corporate feed

ing-line network. Such arrays can be either traveling-wave or reso

nant arrays. A planar structure with a thin and flexible substrate is

a good choice, because it will not disturb the appearance

of

the air

craft, and can be easily integrated with electronic devices for signal

processing.

In this paper, a dual-frequency dual-polarized array antenna is

presented for airborne antenna applications. A multilayer structure

is adopted for dual-band operation. The antenna arrays for the two

frequencies are separated on different layers. To reduce the array's

volume and weight, a series-fed network is used. An ultra-thin sub

strate is chosen in order to make the array conformal, and the array

can be easily placed on an aircraft's fuselage, or inside the aircraft.

The parameters affecting the array's characteristics are discussed,

and the measured return losses, radiation gains, and array patterns

are presented.

Two RTlDuroid 5880 substrates (61 =63 =2.2 and a foam

layer 6 2 = 1.06)

form

the multilayer structure. The thicknesses

of

the substrates and h

2

) are both only 0.13 rom (5 mil). These

ultra-thin and flexible substrates make it possible for the array to

be easily attached onto the aircraf t' s fuselage, or installed inside

the a ircraft . The foam layer has a th ickness of

h

2

=1.6mm. The

dimensions of the array were opt imized by using the full-wave

electromagnetic simulator, I [.

2 1 X Band Antenna and Subarray

The X-band array uses the circular patch as its unit antenna

element. The patch radius, R, for the dominan t TM)) mode at the

resonant frequency (Ir in GHz) can be calculated from [17]

2 Array Design

(1)

Unlike most other elements, the electrical parameters

of

the

substrate will be affected by the temperature and moisture varia

tions occurring in airborne applications, and these affect the

performance

of the antennas. The magnitude of the transmitting

power may also generate a large amount of heat, which results in a

significantly increased temperature. The choice of the substrate is

therefore an important factor in airborne-antenna design . The

configuration

of

the antenna element determines the complexity

of

the array feeding-line network, which controls the size and mass of

the array. The configuration of the feeding-line networks may also

incur different levels of port isolation and pattern polarization.

Important design considerations of a dual-polarized airborne array

antenna are summarized in Table

I.

Our goal is to design a low

mass conformal array antenna for airborne applications. An ultra

thin substrate is used to achieve the

conformal

antenna.

D

The multi layer array structure for dual-band (S band and X

band) operation is shown in Figure

I.

The S-band antenna elements

sit on the top layer , and the X-band antennas are on the bottom

layer. A foam layer

2

) serves as the spacer, and is sandwiched

between the two subst rate layers . One of the important design

considerations for this multilayer dual-band array is that the S-band

antenna element should be nearly transparent to the X-band

antenna elements. Otherwise, the S-band element may degrade the

performance of

the X-band antenna.

y.

x

Figure 1. The multilayer structure of th e dual- band dual

polarized array

antenna.

Table 1. Design considerations

for

the airborne array antenna.

Factor

Impact

Temperature

This is determined by the aerial conditions and delivered power, which will affect the electrical

parameters

ofthe

substrate.

Moisture

The effects due to moisture are similar to the temperature effects.

Electrical parameters

This controls the antenna's nerformance and is mainly changed by large temperature variations.

Feeding-line network

This determines the complexityof the array. Unsuitable antenna elements could result in a bulky

and heavy array.

Isolation

Port-to-port isolation and cross-polarization level can be enhanced by using well-designed

feeing-line networks, such as proximity/aperture coupling and multilayer configurations.

Coupling

For dual-frequency operation, the interference between antennas operating at different

frequencies may affect radiation patterns and gain.

IA P

M

,

Vol. 51,No

.4 August

2009

71



3/9

where O and h (in em) are the relative dielectric constant and

thickness of

the substrate, respectively. At the operating frequency,

fr

=10GHz, an initial value of R of 5.82 mm, calculated from

Equation

I ,

was used. The optimized value

of

5.95

mm

was

obtainedwith the aid

of

IE3D.

The circular patches are fed with microstrip lines at the

circumferential edge, as shown in Figure2a. For a single circular

patch, two microstrip feeding lines are used to feed the circular

patch to generate two orthogonally radiating TM

t

1

modes for dual

polarized operation. Two feed points are located at the edge

of

the

patch, 90

0

away from each other, so that the coupling between

these two ports can be minimized. The port isolation also depends

on the quality factor of the patch. Increasing the substrate's thick

ness decreases the isolation [18]. Therefore, using thin substrates

could improve the quality

of

isolation.

with

F =8.79I

F

,

(2)

, 2R , L H-port

<

l

L- -- --- ::::_ :t------------------- -------------------

Figure 2a. The layout of the X-band antenna, where

L =

106,

W =183, R =

5

.82,

LxI =

22,

and W

xt

=

0.17 (all dimensions

are in mm),

..-.._. _._.._.

L,5

----------------------------------------------------

1

,

,

.

H-port :

Figure 2b.

The

layout of the S-band antenna, where

L

=

106,

W=183

, L

st

=53.89 , L

s2

=44.6 , L

s3

=0.94 , L

s4

=19.31 ,

L

ss

=

34

.17,

W

st

=

4

.9 , and W

s2

=

7.8 (all dimensions

are

in

mm).

Figure2a shows a 4 x 8 dual-polarized X-band array. The V

port and the H port are the input ports for the two orthogonal

polarizations (vertical and horizontal). The array is composed

of

two 4

x

4 subarrays. The corporate-fed power-divider lines split the

input power at eachport to the subarrays.Within each subarray, the

circular patches are configured into four 4

x

1 series-fed resonant

type arrays, which make the total array compact and have less

microstrip line losses than would a purely corporate-fed type of

array [19]. An open circuit is placed after the last patch

of

each

4 x 1 array.The spacing between adjacent circular-patch centers is

about one guided wavelength

g

=

21.5mm at 10 GHz). This is

equivalent to a 360

0

phase shift between patches, such that the

main beam points to the broadside. The power coupled to each

patch can also be controlled by adjusting the size

of

the individual

patch to achieve a tapered amplitude distribution for a lower

sidelobe design. Another advantage of using the series-fed array

configuration is that the array can be easily converted into a travel

ing-wave array, with a matched termination at the end

of

the last

elements, if a steered-beamarray is needed.

2 2 S Band Antenna and Subarray

Figure 3. The geometry of the dual-band dual-polarized array

antenna.

As shown in Figure 2b, the S-band antenna elements are

printed on the top substrate, and are separated from the X-band ele

ments by the foam layer. To reduce the blocking of the radiation

from the X-band elements at the bottom layer, the shape of the S

band elements has to be carefully selected. A ring configuration

was a good candidate, since it uses less metallization than an

equivalent patch element. Here, a square-ringmicrostrip antenna is

used as the unit element

of

the S-band array. Because antenna ele

ments at both frequency bands share the same aperture, it is also

preferred that the number of elements on the top layer be as small

as possible, to minimize the blocking effects.

The stacked X-band and S-band array antennas are shown in

Figure 3. As can be seen in the figure, the four sides of the square

ring element are laid out in such a way that they only cover part of

the feeding lines on the bottom layer, but none

of

the radiating ele

ments. Unlike an ordinary microstrip-ring antenna that has a mean

circumference equal to a guided wavelength, the antenna proposed

here has a mean circumference

of

about 2

g

g

=

82.44mm at

V-port .

(S-band) •

H-port

(X-band)

H-port

(S-band)

72

IA P M

Vol. 51, No

.4

,

August

2009



4/9

• Mean radius of the ring - 2

9

GHz

• Select two operating frequencies I r I I

• Use very thin substrates

10 GHz

• Use Eq. (1)

to

calculate R

• Select I

X1

- 1 '9' w

x1

= 0.17 mm

• Based on (l

s2

- Is1)< (lx1 - 2R)

and (l

s2

+ I

s1)

2 - 2 '9

select

I

s1

and I

s2

• Select I

s3

and W

s3

(50 ohm)

No

• Design the power divider

• Interconnect the patch elements

No

Yes

Yes

Overlay the 3 GHz elements on the 10 GHz elements with

minimum blockage of the circular patches

Figure 4. The design flowchart of the proposed

antenna array.

3 GHz). Although the size of the proposed unit element is larger

than an ordinary ring antenna, its gain is about twice as high,

because

of

its larger radiation-aperture area. The ring is loaded by

two gaps at two of its parallel sides, and these make it possible to

achieve a 50 n input match at the edge

of

the third side without

using a small value

of

Ls

LsI

as mentioned in [20]. For an edge-

fed microstrip ring, if a second feed line is added to the orthogonal

edge, the coupling between the two feeding ports will be high. The

V-port and H-port feeds are therefore placed at two individual ele

ments, so that the coupling between the two ports can be signifi

cantly reduced. Using separate elements seems to increase the

number of antenna elements within a given aperture. However, this

harmful effect could be minimized by reducing the number

of

ele

ments with the use of larger-sized microstrip rings. A design flow

chart of the proposed antenna array is provided in Figure 4.

3. Measurement and Discussion

A dual-band array prototype was fabricated and tested in the

anechoic chamber of the Texas A&M University. The array was

tested for one polarization at one frequency at a time, while the

other three ports were terminated with 50n loads. Detailed simu

lated and measured results are given and discussed in the follow

ing.

3 X-band Array

top of it. The center frequency of both polarizations was at around

9.95 GHz, and the return losses 8

11

and 8

22

) were better than

22 dB. 8

11

was the return loss for the V port, and 8

22

was for the

H port. The isolation

21

or 8

12

)

between the V and the H

polarizations was better than 30 dB at the resonant frequency, and

better than 25 dB over a wide frequency band. These results were

considered excellent for a dual-polarized array for which the feed

ing lines for both polarizations were present at the same layer.

These results were similar to those reported in [4], and the physical

size of the array was reduced, due to the hybrid use

of

the corpo

rate-fed and series-fed configurations.

Normalized measured radiation patterns are shown in Fig

ure 6. Well-defined patterns were observed. Cross-polarization lev

els in the E plane and H plane were 17dB below the co-polarized

beam peaks. It was noted that the dimensions

of

the ground plane

used for the array were about 18.3 em x 10.6 em, which were close

to those of the array's aperture. This could create strong edge

diffraction, and might account for the relatively higher cross

polarization levels. The peak sidelobe levels (SLL) were

-10

to

-13dB, which were normal for the arrays with a uniform ampli

tude distribution. The asymmetric sidelobes of the H port were

caused by its feeding-line network asymmetry with respect to the

array's center. The maximum measured gain was

18.3

dBi, and the

averaged radiation efficiency was 31%. The half-power beamwidth

(HPBW)

of

the x-z plane was 9°, and that

of

the y-z plane was 17°.

This difference was due to the asymmetry of the 4

x

8 array

arrangement.

Figure 5 shows the return loss and the isolation

of

the X-band

array. The measurements were carried out with the S-band layer on

Theoretically, a microstrip antenna has a very good front-to

back ratio (FBR), due to its infinite - or relatively large - ground

IA P

M

Vol. 51, No.4, August 2009

73



5/9

plane . This is similar to the case when an airborne antenna is

mounted on an airframe. Here, with a finite ground plane , the

front-to-back radiation ratios of both the E and H planes were bet

ter than 30 dB. The back radiation was very small , and hence not

shown. A ground plane with a larger dimension can provide a

higher front-to-back radiation ratio, since the coupling and diffrac

tion

of

electromagnetic waves are reduced. Detailed specifications

of the X-band array are summarized in Table 2.

3 2 S Band Array

- - Mea sured E-planeco-pol

--- -- Measured E-plane x-pol

_

_

<

_ Simulated E-plane co-pol

Measured H-plane co-pol

-----

Measured H-plane x-pol

Simulated H-plane co-pol

Figure 6a. The radiation patterns of the X-band array: V-pert

feed, E plane.

he return loss of the S-band array is shown in Figure 7. The

measurements were carried out with the X-band layer under the

S-band layer. About 19 dB return loss was obtained at the resonant

frequency of 2.96 GHz, for both polarizations. Since two separate

elements were used for two polarizations, the results show that the

port isolation was close to 30 dB. Normalized measured radiation

patterns for both polarizations are shown in Figure 8. A typical sin

gle main beam with a wide 3 dB beamwidth was observed . The

cross-polarization levels were better than 20 dB. The maximum

gain of the antenna was measured to be 9.5 dBi, and the averaged

radiation efficiency was 81%. The HPBW of the S-band array was

about 56° on each plane. The front-to-back radiation ratios on both

planes were better than 34 dB for the V port and 25 dB for the H

port, which indicated that the dimensions of the ground plane were

acceptable for the S-band antenna.

(dB) -30 -20 -10

Measured E-plane co-pol

Measured E-plane x-pol

Simulated E-plane co-pol

Figure 6b. The radiation patterns of the X-band array: V-port

feed, H plane.

-20

- Measured S11

........Simulated S11

> < Measured S12

-10 ...

o

·30 .

-20 -10


0° - - - - - Measured H-plane x-pol


Figure 6c. The radiation patterns of the X-band array: H-port

feed, E plane.

-30 .

-20 .

-40

9.5 9.6 9.7 9.8 9.9 10 10.1 10.2 10.3 10.4 10.5

Frequency (GHz)

Figure Sa. The S parameters of the X-band array, where

port

1

is the V-port feed for vertical polarization.

o

Figure Sb. The S parameters ofthe X-band array, where port 2

is the H-port feed for horizontal polarization.

Figure 6d. The radiation patterns of the X-band array: H-port

feed, H plane.

74

IAa P

M

,

Vol. 51, No.4,

August2009



6/9

Table

2. A

summary of the measured and simulated results for the X-band

and

S-band array antennas.

X

-Band S-Band

Polarization

V

Port

H

Port

V

Port

HPort

Frequency (GHz)

Measurement 9.8-9.98 9.81-10.0 2.94-2.96 2.94-2.96

Simulation 9.91-9.99 9.9-10.0 2.94-2.96

2.94-2.96

Bandwidth (%)

Measurement

1.8

2.3

1.03 1.03

Simulation

1.0 1.0 1.03 1.03

Gain (dBi)

Measurement

18.3

17.3 9.5

7.9

Simulation 17.6 17.6 8.72

8.73

Efficiency (%) Measurement 32.4 28.8 96.8 66.8

Simulation 27.5 27.5 80.9

80.9

HPBW (degrees)

E plane

17°

8.9° 58° 59°

Hplane

9.5°

7 4°

53° 52°

Peak SLL (dB)

Measurement

-12

.3 -1 0.0

None

None

Simulation -13 .0 -13 .0

FBR (dB) -30

-30 -34 .8

-25.5

Isolation (dB)

> 3I.l > 25.3 >36.4

>33 .8

X to S band X to S band S to X band S to X band

3.3 Mutual Coupling Effects of Two Layers

Figure

7.

The

S parameters

of the S-band

array, where port 1

is the V-port feed for vertical polarization, and port 2 is the H

port

feed for horizontal polarization.

- - Measured [- plane co-pol

Measured [- planes -pot

Measured If-plane co-pol

Measur ed ..plane x..pol

• SimulatedE-plane co-pol


- - Measured E-plane co-pol

Measured [ -plane r-pel


- Measu red H-plan e s-pot

• S imulat ed [ - planeco-pol

Simulated If-planeco-pol

-90

Figure

8a. Radiation

patterns

ofthe

S-band array

:

V-port

feed.

Figure 8b. Radiation patterns of the S-band array: H-port feed.

ments for the S-band array, with or without the presence of the X

band array, including the S parameters and the radiation patterns.

When the X band was presented, the isolation of S-to-X (from the

ports

of

the S-band antenna to the ports

of

the X-band) was

between 33 dB and 42 dB; the isolation of X-to-S was better than

25 dB.

It

was observed that increasing the spacing between the S

band and the X-band antennas did not significantly improve the

isolation. Instead, it raised the center frequency

of

the S-band

antenna, and vice versa. Consider the case where the foam-layer

thickness

z

)

is changed within

±O.5 mm

, If h

z

is increased by

3.2.15.1

- - - - Measured511

Measured 522

- Measreud 521

-e-o-e-Simulated S

- Simulated S22

2.95 3 3.05

Frequency (GHz)

2.9

.85

-20 - - - - - -- - - - -- - - - - - -- - - - -- - - - - - - -- -- - - - - - - - - - -

-30

·10

-40

-50

2.8

CD

Simulated results

of

the return losses and radiation patterns

from IE3D are also shown for comparison. Good agreement was

observed for both frequency bands. Small discrepancies in the

resonant frequencies may be attributed to the accuracy of the

permittivity and the thickness dimension ofthe foam layer given by

the manufacturer. The former value played a more important role.

The resonant frequency shifts from 3 GHz to 2.95 GHz when the

dielectric constant of the foam layer

6Z)

changes from 1.06 to

I.l2 , a 5.7% change within the inaccuracy

of

the fabrication proc

ess. The effects due to the thickness ofthe foam layer are described

in the following section. The specifications of the S-band array are

summarized in Table 2.

The results presented here for both the X and S bands were

measured with the concurrent presence of

both antenna layers

(dual-band operation). However, measurements of the single layer

without the presence of the other layer,

i.e.,

single-band operation,

were also conducted, to investigate the mutual-coupling effects

between the elements of different frequency bands.

It

was found

that there were no distinct variations between the two measure-

IA P M

Vol. 51, No.4,

August 2009

75



7/9

Dual layer

- - - X-ba nd la yer only

-90

Figure

9a.

Comparisons

of

the X-band

radiation patterns of

the If-port feed for the E plane.

5 Acknowledgment

The authors would like to thank the Rogers Corporation for

donating the high-frequency laminates, and Mr. Ming-Yi

Li of

Texas A&M University for his technical assistance and helpful

suggestions.

6 References

1. A. Vallecchi and G. Gentili, Design of Dual-Polarized Series

Fed Microstrip Arrays with Low Losses and High Polarization

Purity, IEEE Transactions on Antennas and Propagation, AP-S3,

5, May 2005, pp. 1791-1798.

3. X. Qu, S. Zhong, Y. Zhang, and W. Wang, Design of an SIX

Dual-Band Dual-Polarised Microstrip Antenna Array for SAR

Applications,

lET

Microwave, Antennas, and Propagation, 1, 2,

April 2007, pp. 513-517.

5. G. Chattopadhyay and J. Zmuidzinas, A Dual-Polarized Slot

Antenna for Millimeter Waves, IEEE Transactions on Antennas

and Propagation, AP-46, 5, May 1998, pp. 736-737.

2. S. Gao and A. Sambell, Dual-Polarized Broad-Band Microstrip

Antennas Fed by Proximity Coupling, IEEE Transactions on

Antennas and Propagation, AP-S3, 1, January 2005, pp. 526-530.

4. S. Zhong, X. Yang, S. Gao, and J. Cui, Comer-Fed Microstrip

Antenna Element and Arrays

of

Dual-Polarization Operation,

IEEE Transactions on Antennas and Propagation, AP SO 10,

October 2002, pp. 1473-1480.

-30dB)

Dual layer

- - - X-band layer only

Figure

9b. Comparisons of the X-band radiation patterns of

the

H-port feed for

the

H plane.

0.1 mm, the frequency is raised by 40 MHz; while if

h

2

is

decreased by 0.1 mm, the frequency is reduced by about 60 MHz.

6. K. Mak, H. Wong, and M. Luk, A Shorted Bowtie Patch

Antenna with a Cross Dipole for Dual Polarization, IEEE Anten

nas and WirelessPropagation Letters, 6, 2007, pp. 126-129.

For the X-band array, only small variations in the sidelobe

levels were observed, and the measured peak gain dropped about

0.5 dB with the presence of the top S-band layer. Comparisons of

the radiation patterns

of

the H port are shown in Figure 9. The S

band layer presented little effect on the performance of the X-band

layer. The statement that one antenna layer was transparent to the

other one was therefore confirmed.

7. S. Gao and A. Sambell, Dual-Polarized Broad-Band Microstrip

Antennas Fed by Proximity Coupling, IEEE Transactions on

Antennas and Propagation, AP-S3, 1, January 2005, pp. 526-530.

8. K. Ghorbani and R. Waterhouse, Dual Polarized Wide-Band

Aperture Stacked Patch Antennas, IEEE Transactions on Anten

nas and Propagation, AP-S2, 8, August 2004, pp. 2171-2174.

4 Conclusions

A dual-frequency (S-band and X-band) dual-polarization

array antenna has been developed. An ultra-thin structure was

adopted for the purpose of use with aircraft. The conformal array

can be installed on the airframe or inside the aircraft, due to its

small size and light weight. The X-band array used a series-fed

configuration to save the space

of

the feeding-line network. The S

band array adopted a larger radiation aperture to decrease the num

ber of elements, to reduce the blockage, and to enhance the radia

tion gain. The V and H ports were put on two separate elements to

achieve high isolation. More subarrays could be assembled to

obtain higher gain with a narrower beamwidth. The newly devel

oped dual-frequency dual-polarization array antenna should be use

ful for future wireless communications, remote sensing, surveil

lance, radar systems, and UAV applications.

9. D. Krishna, M. Gopikrishna, C. Aanandan, P. Mohanan, and K.

Vasudevan, Compact Dual-Polarized Square Microstrip Antenna

with Triangular Slots for Wireless Communication, lEE Electron

ics Letters, 42,16, August 2006, pp. 894-895.

10. K. Wong and T. Chiou, Design

of

Dual Polarized Patch

Antennas Fed by Hybrid Feeds, Proceedings of the IEEE Fifth

International Symposium on Antennas, Propagation, and EM The

ory, Beijing, China, August 2000, pp. 22-25.

11. Y. Guo and K. Luk, Dual-Polarized Dielectric Resonator,

IEEE Transactions on Antennas and Propagation, AP-51, 5, May

2003,pp.1120-1123.

12. B. Lindmark, S. Lundgren, J. Sanford, and C. Beckman, Dual

Polarized Array for Signal-Processing Applications in Wireless

Communications,

IEEE Transactions on Antennas and Propaga

tion, AP-46, 6, June 1998, pp. 758-763.

76

I A a P M , Vol. 51, No

.4

, August 2009



8/9

13. A Parfitt and N. Nikolic, A Dual-Polarised Wideband Planar

Array for X-Band Synthetic Aperture Radar, IEEE International

Symposium on Antennas and Propagation Digest, 2, Boston, MA,

July 2001, pp. 464-467.

14. H. Wong, K. Lau, K. Luk, Design

of

Dual-Polarized L-Probe

Patch Antenna Arrays with High Isolation, IEEE Transactions on

Antennas and Propagation, AP-52, 1, January 2004, pp. 45-52.

17. C. Balanis, Antenna Theory, Second Edition, New York, John

Wiley & Sons, Inc., 2002.

18. J. R. James and P. S. Hall (eds.), Handbook of Microstrip

Antennas, Volume 1, London, Peter Peregrinus, 1989.

19. R. Garg, P . Bhartia,

1.

Bahl, and A. Itt ipiboon, Microstrip

Antenna Design Handbook, Norwood, MA, Artech House, Inc.,

2001.

15. J . Skora, A. Sanz, and R. Fabbra, Dual Polarized Phased

Array Antenna for Airborne L-Band SAR, IEEE MTT-S Interna

tional Conference, Long Beach, CA, July 2005, pp. 192-196.

16. IE3D, Version 10.2, Zeland Software Inc., Fremont, CA, 2004.

20 . P. M. Bafrooei and L. Shafai, Characteristics of Single- and

Double-Layer Microstrip Square-Ring Antennas,

IEEE Transac

tions on Antennas and Propagation, AP-47, 10, October 1999, pp.

1633-1639.

Introducing the Feature Article Authors

Texas -A&M University, he conducted research on wireless power

transmission, power combining, ultra-wideband antennas, and

phased arrays. In 2007, he joined Intelligent Automation Inc.,

Rockville, MD, where he is involved in research and development

of

advanced antennas and RP/microwave systems, including

conformal antennas, metamaterial antennas, VAV collision avoid

ance radar, airborne weather radar, through-the-wall noise radar,

and RPID sensors for biological-warfare agent detection and struc

ture health monitoring.

Kai

Chang

received the BSEE degree from the National Tai

wan University, Taipei, Taiwan; the MS degree from the State

University

of

New York at Stony Brook; and the PhD degree from

the University of Michigan, Ann Arbor; in 1970, 1972, and 1976,

respectively.

From 1972 to 1976, he worked for the Microwave Solid-State

Circuits Group, Cooley Electronics Laboratory

of

the University

of

Michigan as a Research Assistant. From 1976 to 1978, he was

employed by Shared Applicat ions , Inc., Ann Arbor, where he

worked in computer simulation

of microwave circuits and micro

wave tubes . From 1978 to 1981, he worked for the Electron

Dynamics Division, Hughes Aircraft Company, Torrance, CA,

Yu-Jiun

Ren

received the BSEE from Nat ional Chung

Hsing University, Taiwan; the MS degree in Communication Engi

neering from National Chiao-Tung University, Taiwan; and the

PhD degree from Texas A&M Univers ity at Col lege Stat ion; in

2000,2002,

and 2007, respectively. From 2002 to 2003, he was a

research assistant with the Radio Wave Propagation and Scattering

Laboratory, National Chiao-Tung University, and involved in

mobile-radio propagation, channel modeling, and cell planning. At

Shih-Hsu

Hsu received the BSEE degree from National

Cheng-Kung University, Taiwan; the MS degree in Electrical Engi

neering from the University of Wisconsin-Madison; and the PhD

degree from Texas A&M University at College Station; in 2000,

2004, and 2008 , respectively. At Texas A&M University, his

research activities involved microstrip reflectarrays, reconfigurable

antennas, and wideband antennas. In October 2008, he joined

Applied Optoelectronics, Inc., where he is involve in high-speed

laser design.

IA P

M

Vol. 51, No.4, August2009

77



9/9

where he was involved in the research and development of

millimeter-wave solid-state devices and circuits, power combiners,

oscillators and transmitters. From 1981 to 1985, he worked for the

TRW Electronics and Defense, Redondo Beach, CA, as a Section

Head, developing state-of-the-art millimeter-wave integrated cir

cuits and subsystems including mixers, VCOs, transmitters,

amplifiers, modulators, up-converters, switches, multipliers,

receivers, and transceivers. He joined the Electrical Engineering

Department

of

Texas A&M University in August 1985 as an

Associate Professor, and was promoted to a Professor in 1988. In

January 1990, he was appointed Raytheon E-Systems Endowed

Professor

of

Electrical Engineering. His current interests are in

microwave and millimeter-wave devices and circuits, microwave

integrated circuits, integrated antennas, wideband and active anten

nas, phased arrays, microwavepower transmission, andmicrowave

optical interactions.

Dr. Chang has authored and coauthored several books. He

served as the editor of the four-volume Handbook ofMicrowave

and Optical Components, published by John Wiley in 1989 and

1990 (second edition 2003), and the editor for the Wiley

Encyclopedia

of

RF and Microwave Engineering (six volumes,

2005). He is the editor of Microwave and Optical Technology Let

ters, and the Wiley book series in Microwave and Optical

Engineering (over 70 books published). He has published over 450

papers, and many book chapters in the areas of microwave and

millimeter-wave devices, circuits, and antennas. He has graduated

over 25 PhD students and over 35MS students.

Dr. Chang has served as technical committee member and

session chair for IEEE MTT-S, AP-S, and many international

conferences. He was the Vice General Chair for the 2002 IEEE

International Symposium on Antennas and Propagation. He

received the Special Achievement Award from TRW in 1984, the

Halliburton Professor Award in 1988, the Distinguished Teaching

Award in 1989, the Distinguished Research Award in 1992, and

the TEES Fellow Award in 1996 from the Texas A&M University.

Dr. Chang is a Fellow of the IEEE.

78

Changes

Address

rDelivery Problems

Information regarding subscriptions and addresses is man

aged by IEEE headquarters. It is not maintained, nor can it be

changed, by any member of the Magazine staff. If you are a mem

ber

of

the IEEE, your subscription is sent to the address in your

IEEE member record. Your address can be confirmed or updated

by visiting the Web page dealing with delivery of IEEE publica

tions:

http://www.ieee.org/web/aboutus/help/products_services/

subscriptions.html

This page also has information about publication delivery, and a

link to an online form that can be used to inquire about missing or

delayedpublications.

You can also update your address information by contacting

IEEE headquarters:Member Address Records, IEEEHeadquarters,

445 Hoes Lane, Piscataway NJ 08855-1331 USA; Tel: +1 (908)

981-0060 or

+

1 (800) 678-4333; Fax: +1 (908) 981-9667; E-mail:

address. [email protected]. If you are an institutional or other non

member subscriber, contact IEEE Customer Service at the above

address, telephone, and fax numbers; E-mail:

[email protected].

Please do not

send requests related to the above items to any

member of theMagazine Staff.

IA P M

Vol. 51.No.4, August2009

A Dual-Polarized Planar-Array Antenna for S-Band and X-Band Airborne Applications-5aa

Documents

Transcript of A Dual-Polarized Planar-Array Antenna for S-Band and X-Band Airborne Applications-5aa