Research ArticleDualCircularlyPolarizedPatchAntennawith Improved InterportIsolation for S-Band Satellite Communication

Haq Nawaz ,1 Ahmad Umar Niazi ,2 and Mansoor Ahmad 3

1Electrical Engineering, University of Engineering and Technology (UET), Lahore, Pakistan2Electronics Engineering, University of Engineering and Technology (UET), Taxila, Pakistan3Department of Electronics, University of Buner, Buner, Khyber Pakhtunkhwa, Pakistan

Correspondence should be addressed to Haq Nawaz; hnawaz@sabanciuniv.edu

Received 25 May 2021; Revised 12 August 2021; Accepted 3 September 2021; Published 17 September 2021

Academic Editor: Ahmad Safaai-Jazi

Copyright © 2021 Haq Nawaz 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.

,is paper presents a bi-port, single-layered (planar), dual circularly polarized (CP) patch antenna with improved interportisolation for S-band satellite telemetry and telecommand applications. ,e dual-port, planar antenna is based on a square-shapedradiator with trimmed corner to achieve CP characteristics (RHCP and LHCP) for excitations from respective ports. However, theRF isolation between the two ports is very low due to strong power leakage from transmit (Tx) to transmit (Rx) port.,e externallyemployed tunable self-interference cancellation (SIC) circuit achieves high isolation between orthogonal ports while axial ratio(AR) is ≤3 dB for both right and left handed circular polarizationmodes.,e employed single-tap SIC circuit/loop attains the highinterport isolation through signal inversion mechanism.,e proposed antenna design achieves ≥72 dB peak interport isolation inaddition to ≥30 dB and 15 dB port to port isolation over the isolation or SIC bandwidths of 15MHz and 90MHz (−10 dBbandwidth for both ports), respectively. ,e port to port isolation performance is improved without significant degradation inantenna radiation characteristics. ,e validation model of the presented planar antenna based on single element characterizesmuch better measured interport isolation performance compared to those dual CP printed antennas reported earlier as endorsedthrough detailed comparison

1. Introduction

In order to eliminate the requirements of polarizationalignment of satellite space link antennas, dual circularpolarized radiators are deployed to feed dish-type satellitecommunication terminal antennas [1, 2]. Such circularpolarized (CP) antennas in the satellite communicationapplications offer flexible orientations of the transmitter andreceiver antennas [3]. ,e dual CP antennas can also play avital role to minimize the fading loss and can be utilized forfrequency reuse applications. Normally, dual CP waveguidehorns are deployed as feeds for satellite dish antennas.However, dual CP microstrip patch antennas can be veryuseful as feeds for such applications as they can offer a lowprofile, easy manufacturing, conformability, and convenientintegration with other RF blocks in transmit and receivechains. Such dual CP microstrip antennas can also act as

useful building blocks for aperture and feeds arrays insatellite communications.

,e interport isolation is the deciding parameter todetermine the viability of dual CP microstrip (planar) an-tennas for satellite communication applications. ,e overallsystem noise temperature or noise figure is highly dependenton the interport coupling of feed antennas [4]. For instance,in receive mode operation, the high mutual coupling be-tween antenna’s ports will increase the equivalent noisetemperature of the receiver at satellite ground terminal.,us, using a dual CP feed antenna with low or poorinterport isolation will degrade the system sensitivitythrough direct contribution of additional noise.

However, it is very difficult and challenging task toachieve the high interport isolation for shared aperture(radiator) antenna with dual CP characteristics due topresence of both vertical and horizontal electric field

HindawiInternational Journal of Antennas and PropagationVolume 2021, Article ID 8022207, 10 pageshttps://doi.org/10.1155/2021/8022207

components in each CP mode (RHCP and LHCP). ,epreviously reported works on dual-port antennas with linearco-polarized characteristics have focused on suppression ofinterport coupling through signal inversion-based cancel-lation circuits [5] or balanced receive mode operation [6] toachieve high interport isolation for antennas with linear co-polarized characteristics. ,e combination of the signalinversion and differential receive mode technique offers niceinterport isolation for such linear co-polarized antennas [5].However, the differential feeding-based isolation techniqueis not viable for shared aperture trimmed corner CPantennas.

In this paper, a planar, squared-shaped radiating elementwas utilized with single corner trimming or truncation toproduce dual CP characteristics when excited from therespective orthogonal ports. ,e single-layer antennastructure avoids multilayered complex printed circuit board(PCB) or stacked structures which are employed in con-ventional dual CP antennas. ,e improved interport iso-lation is achieved through a signal inversion-baseddecoupling network between orthogonal ports of CP ele-ment. ,e single-tap decoupling network is composed oftwo 3 dB couplers, a tunable phase shifter, and voltagecontrolled attenuator. ,e tunable self-interference cancel-lation (SIC) circuit also offers the possibility of setting thepeak isolation at intended frequency within antenna’s im-pedance bandwidth.

,e rest of the paper is organized as follows. Section 2details the design and simulated characteristics of a dual-port, dual circularly polarized antenna based on singlesquare-shaped element with trimmed corner. Section 3presents the design, simulations, and analysis of dual CPantenna with integrated single-tap SIC loop to achieveimproved isolation between Tx and Rx ports. ,e imple-mentation details and measurement results for the antennawith integrated SIC circuit are presented in Section 4. ,econclusions are drawn in Section 5.

2. Two-Port, Dual Circularly PolarizedAntenna Element

,e proposed dual CP antenna is based on a square-shapedradiating element with two orthogonal feeds as shown inFigure 1. ,e dual CP characteristics were obtained throughproper corner trimming or truncation when patch is excitedfrom respective orthogonally placed ports. ,e antenna wasdesigned on 1.6mm thick FR4 substrate (εr � 4.4,tanδ � 0.02).

,e proposed dual CP antenna is simulated by usingKeysight Advanced Design System (ADS) and HFSS soft-ware [7]. ,e corner-trimmed mechanism generates twoorthogonal E-field components with equal magnitude and90° phase difference when patch is excited through respectiveport to produce CP characteristics as illustrated in Figure 2.,e proposed antenna will be right-hand circular polarized(RHCP) when port 1 is excited, and similarly, it is left-handcircular polarized (LHCP) for port 2 excitation. ,e cornertruncation topology offers the advantage to implement CPantenna on single-layered PCB (radiating element and feeds

on same side of PCB) as compared to other feeding con-figurations including cross-slot fed, circularly polarizedpatches [8] based on three-layered stacked structure.

,e simulated reflection coefficients (S11, S22) andinterport coupling (S21) results for proposed bi-port, dual CPantenna are shown in Figure 3. ,e 10 dB return lossbandwidth for proposed dual port, dual CP antenna is betterthan 75 MHz for each port as clear from simulation results.As expected and clear from simulated interport couplingresults, both ports of dual CP patch antenna are not wellisolated as the isolation levels are around 8 dB only.

Ansys HFSS simulated peak realized gain and axial ratioresults for proposed corner-trimmed, CP antenna are given inFigure 4. For brevity, only the simulated results for port 1excitation (RHCP mode) are presented here. Due to symmetryof proposed antenna structure, the simulated peak realized gainand axial ratio results for port 2 (LHCP) will be identical tothose observed for RHCP mode. As clear from simulationresults in Figure 4, the proposedCP antenna achieves axial ratio(AR) ≤1dB with simulated peak realized gain of better than4.8 dBi at centre design frequency of 2.4GHz. Moreover, asclear from AR versus theta simulation results in Figure 5, theantenna achieves a wider 3 dB AR beamwidth.

Ansys HFSS simulated gain versus theta results fordifferent phi cuts (at V � 0°, 45°, and 90°) are shown inFigure 6 for RHCP mode (port 1 excitation). ,e simulatedboresight gain is around 4.7 dBi for all three V cuts. ,esesimulated gain results demonstrate the good CP charac-teristics of antenna as it provides almost same gain levels atdifferent values of phi (V). ,e gain of the proposed dual CPantenna can be enhanced by using a low loss substrate whichwill improve the radiation efficiency of printed patch to offermore gain levels.

3. Dual Circularly Polarized Antenna with SICCircuit for Improved Isolation

After validating the radiation characteristics of proposedantenna, the interport isolation of dual-port, dual CPantenna presented in Section 2 was improved by using anexternal SIC circuit between port 1 and port 2. ,e ex-ternal SIC circuit is composed of two 3 dB couplers, atunable RF attenuator, and voltage controlled phaseshifter as illustrated in Figure 7. 3 dB coupler 1 placed atport 1 is used to tap a RF signal to add its modified versionat port 2 through coupler 2. ,e tunable phase shifter andattenuator are used to achieve required signal inversionconditions for Tx signals [5]. ,ese signal inversionconditions require that RF signals from each path(through antenna and SIC network) should be equal inmagnitude and 180° out of phase when they are combinedat port 2 for cancellation. As stated earlier in Figure 3, theantenna interport coupling is around −8 dB which re-quires same levels of coupling through SIC network alongwith 180° phase difference between these two signals.

,e interport isolation improvement capabilities of SICcircuit with dual CP antenna were endorsed through co-simulations in Keysight ADS software. ,e co-simulationschematic is shown in Figure 8, where the EM model of bi-

2 International Journal of Antennas and Propagation

10 dB R.L. B.W. ≥ 75 MHz

X: 2.435Y: -7.906

0

-5

-10

-15

-20

-25

Mag

nitu

de (d

B)

2.25 2.3 2.35 2.4Frequency (GHz)

2.45 2.5 2.55 2.6 2.65

S11S22S21

Figure 3: ,e simulated reflection coefficients (S11, S22) and interport coupling (S21) results for proposed dual-port, dual CP patch antenna.

29 m

m

29 mm

Port 2

Port 1

19 mm

4.6

mm

4.6 mm

1mm

Figure 1: ,e proposed corner-trimmed, dual CP, 2.4 GHz patch antenna.

RHCP LHCP

Port 1 (RHCP)

Port 2 (LHCP)

5.0 dBi

1.5 A/m

y

xz

yx xy

z z

Figure 2: ,e simulated surface current distributions and gain patterns for RHCP and LHCP characteristics of the proposed dual CPantenna at f� 2.4GHz.

International Journal of Antennas and Propagation 3

Axial Ratio

1

1.5

2

2.5

3

3.5

Axi

al R

atio

(dB)

-60 -40 -20 0 20 40 60 80-80Theta (deg.)

Figure 5: ,e simulated axial ratio versus theta results for proposed dual-port, dual CP antenna when excited for RHCP mode (port 1excitation).

Axi

al R

atio

(dB)

Peak

Rea

kize

d G

ain

(dBi

)

2.25 2.3 2.35 2.4Frequency (GHz)

2.45 2.5 2.55 2.6 2.65

Axial RatioPeak Realized Gain

4.5

4

3.5

3

25

20

15

10

5

Figure 4:,e simulated axial ratio and peak realized gain results for the dual-port, dual CP antenna when excited for RHCPmode (port 1).

0

-5

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-15

-20

-25

-30

Gai

n (d

Bi)

Theta (Degrees)

phi=0 degreephi=45 degreephi=90 degree

-100 -50 0 50 100 150-150

Figure 6: ,e simulated gain versus theta results at V � 0°, 45°, and 90° cuts for dual-port, dual CP antenna excited for RHCP mode (port 1excitation).

4 International Journal of Antennas and Propagation

port, dual CP antenna was used in schematic simulations.,e phase shifter and attenuator in SIC loop were tuned toset the required SIC conditions to achieve the high isolationbetween port 1 and port 2. ,e simulation results arepresented in Figure 9 where the interport isolation per-formance results for dual CP antenna with and without SICcircuit are presented for the comparison.

As clear from Figure 9, the peak isolation was ≥73 dB at2.43GHz frequency as compared to ∼8 dB when no SICcircuit was used. ,us, more than 65 dB improvement inpeak isolation is contributed by SIC circuit. Moreover, thesimulated isolation was ≥30 dB and 18 dB within 20MHzand 100MHz bandwidths, respectively, as clearly indicatedfor results in Figure 9.

It is important to mention here that SIC capabilities ofexternal circuit are highly sensitive to phase and attenuationvariations of phase shifter and attenuator in the SIC loop assuch variations will directly disturb the intended signalinversion conditions. ,e SIC circuit has the ability to tuneout or suppress the interport isolation degradation resultingfrom environmental reflections in real-time deploymentscenarios of proposed dual CP antenna [5]. ,e proposedSIC mechanism provides narrow band isolation perfor-mance as the single-tap SIC circuit has the limitation ofsetting signal inversion SIC conditions ideally for singlefrequency only. However, two-tap SIC circuits can providecomparatively wideband isolation or SIC performance asdemonstrated in [9].

Dual CP trimmed-patch

3 dB coupler 1

variablephase shi�er

variable attenuator

SIC Network

Rx Port

Tx Port

3 dB coupler 2

Figure 7: ,e dual CP trimmed-corner planar antenna with single-tap network/loop for improved interport isolation through SI sup-pression at Rx port.

CouplerSingle DualCP antenna_feedforw ard

S_Param

S-PARAMETERS

M Sub

COUP3 1__0

SP1Start=2 GHzStop=3 GHzStep=0.001 GHz

CouplerSingleCOUP1Coupling=3 dBZRef=50 OhmPhaseShi�SML

PS1Phase=214.9 {t}ZRef=50 Ohm

TermTerm1Num=1Z=50 Ohm

PadPAD1NetType=PiLoss=2.7 dB {t}

MSUBMSub1H=1.6 mmEr=4.4TanD=0.01

TermTerm2

132

231

Num=2Z=50 Ohm

Coupling=3 dBZRef=50. Ohm.

Figure 8: ,e schematic for co-simulation of dual CP antenna with SIC circuit.

International Journal of Antennas and Propagation 5

,e tunable SIC circuit can be used to set the peakisolation notch frequency through variations in attenuationand phase to set SIC conditions for intended frequency. Inother words, any frequency with peak isolation can beachieved within required impedance bandwidth of dual CPantenna. ,ree example cases are presented here throughsimulation as shown in Figure 10. ,e SIC circuit is tuned toachieve ≥70 dB interport isolation at 2.4GHz, 2.43GHz, and2.46GHz frequencies as illustrated in Figure 10. Conse-quently, the SIC bandwidth can also be adjusted as perrequirements of wireless communication link. For instance,the 20MHz SIC band with ≥30 dB isolation is 2.39GHz to2.41GHz for the case of peak isolation notch frequency of2.4GHz. Similarly, it is 2.45GHz to 2.47GHz for the case ofthe peak isolation notch frequency tuned at 2.46GHz.

4. Prototype of Antenna with Integrated Single-Tap SIC Circuit

,e validation model or prototype of the bi-port, dual CPprinted antenna with integrated single-tap SIC network isdepicted in Figure 11. ,e complete structure was imple-mented on 1.6mm thick single-layered FR4 substrate withεr � 4.4 and tanδ � 0.02. As indicated in Figure 11, both 3 dBdirectional couplers are based on microstrip coupled linetopologies. ,e coupled ports of these directional couplersare intended for tapping of RF signals from respective ports,as shown in Figure 11. ,e SMD versions of JSPHS-2484+and EVA-3000+ from mini-circuits are utilized as variablephase shifter and attenuator, respectively. ,e EVA-3000+variable attenuator offers typical attenuation variations of3.5 dB to 24 dB for the tuning voltage range of 8V to 0V,while the JSPHS-2484+ variable phase shifter can offer thephase variations of 0° to 180° when the tuning voltage isvaried from 0 to 15 Vdc.

,e validation model of the presented antenna wascharacterized through experimentation in lab environmentwhere the reflections from surroundings may result in severedegradation of interport isolation performance of suchantennas. However, the employed SIC network offers

capabilities to achieve high interport isolation even in thepresence of such environmental reflections. ,e interportisolation characteristics of implemented antenna wererecorded through tuning of variable attenuator and phaseshifter for setting the loop attenuation and phase values toestablish the required SIC conditions. ,e tuning in thisfashion will achieve the optimum isolation levels at requiredresonating frequency of trimmed-corner patch as discussedearlier. ,e measured S11, S22, and S12 results for dual-port,dual CP antenna with integrated SIC network are presentedin Figure 12. As clear frommeasured results in Figure 12, thepeak isolation exceeds 72 dB at 2.45GHz frequency for thevalidation model of antenna integrated with single-tap SICnetwork as compared to around 8 dB isolation for the case ofantenna with no SIC circuit. Moreover, the recorded iso-lation levels ≥30 dB and 15 dB across the SIC bandwidths of15MHz and 90MHz, respectively.

,e measured peak gains and axial ratio versus fre-quency results for both RHCP and LHCP modes of vali-dation model of dual-port trimmed corner patch integratedwith SIC network are shown in Figure 13. As clear fromthese measurements, the peak gain is better than 4.5 dB forboth RHCP and LHCP modes where each mode is excitedthrough respective port of the antenna prototype (Fig-ure 11).,emeasured gain levels are higher than 4.3 dB overthe entire operating bandwidth of the antenna.,is indicatesthat no significant degradation in radiation performance isresulting when the SIC network is used between two portsfor improved interport isolation performance of presenteddual-port patch antenna. Moreover, the measurement re-sults of axial ratio versus frequency for antenna prototypeindicate better than 3.5 dB axial ratio over the entire im-pedance bandwidth of the implemented dual CP antenna.

,e experimental results of axial ratio versus elevationangle (theta) for excitation of both ports (RHCP and LHCPmodes) of presented antenna’s prototype are given in Fig-ure 14. ,e presented dual-port, dual CP antenna offers verywide 3 dB axial ratio beamwidth in the elevation plane asclearly endorsed by the measurement results shown inFigure 14.

10 dB R.L. B.W. ≥100 MHzIsolation ≥ 18 dB in 100 MHz

Isolation ≥ 30 dB in 20 MHz

Peak isolation ≥ 73 dBX: 2.43Y: -73.78

0

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-40

-50

-60

-70

2.25 2.352.3 2.4 2.5 2.62.45Frequency (GHz)

Mag

nitu

de (d

B)

2.55 2.65

Figure 9: ,e simulated S11, S22, and S12 results for dual-port, dual CP patch antenna with external SIC circuit to achieve the improvedinterport isolation.

6 International Journal of Antennas and Propagation

Peak isolation ≥ 73 dB @ 2.43 GHz

-20

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1 m

agni

tude

(dB)

2.35 2.4 2.45Frequency (GHz)

2.5

Peak isolation ≥ 70 dB @ 2.4 GHz

Peak iso

lation

≥ 73 dB @

2.46

GHz

Figure 10: ,e simulated interport isolation results for three cases of peak isolation notch frequencies tuned at 2.4GHz, 2.43GHz, and2.46GHz.

P2

3 dB coupler 1

3 dB

coup

ler 2

var. phaseshi�er

gnd

gnd

Vtune (0-8 V)

Var. atten.P1

+5 V

Vtune (0-15 V)

100 mm

100

mm

trimmed corner patch

Figure 11: ,e validation model or prototype of dual CP antenna with integrated SIC circuit.

-10 dB Bandwidth ≥ 90 MHz

Peak Isolation ≥ 72 dB

Isolation ≥ 15 dB and 30 dB over 90 MHz and 15 MHz bandwidths

0

-10

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-70

Mag

nitu

de (d

B)

2.41 2.42 2.43 2.44Frequency (GHz)

2.45 2.46 2.47 2.48 2.49

S11S22S21

Figure 12: ,e measured S11, S22, and S12 results for dual-port, dual CP patch antenna with integrated SIC network to achieve improvedisolation.

International Journal of Antennas and Propagation 7

,e measured 2D radiation patterns for co- and cross-polarization levels versus theta for the prototype of dual-port, dual CP antenna are given in Figure 15 for both RHCPand LHCP modes. ,e measured gain levels are higher than4.5 dB at boresight for each of the intended polarizations.Moreover, the cross-polarization levels are more than 20 dBlower than the respective co-polarization levels which in-dicate the excellent polarization purity for both modes.

As detailed in Table 1, the interport isolation charac-teristics of our presented antenna have been compared tosome previously reported designs of dual CP antennas. Bothdual CP antennas reported in [1, 3] have achieved maximumisolation of 23 dB and 15.7 dB, respectively, for Ku-bandapplications. As compared to these two antennas, ourproposed antenna offers ≥72 dB peak isolation for S-bandapplications. Moreover, it is important to note that lowinterport isolation levels are inherent in dual-port, dual CPpatch antennas at low frequencies [22]. ,e dual-band (S

and C bands), dual CP antenna reported in [10] is based oncomplex five-layered stacked structure. ,e measured peakisolation for this antenna is ∼9 dB and 10 dB, and return lossbandwidth is around 150MHz for low-frequency band (S-band). For high band (C-band), the measured peak isolationis ∼27 dB and measured return loss ≥10 dB for both ports.Again our proposed antenna is based on low profile planarstructure and offers better interport isolation performancefor S-band applications.

,e compact dual-band circular polarized antenna re-ported in [11] offers the measured average isolation levels of5.8 dB and 5 dB for band 1 and band 2, respectively.Moreover, the structure is composed of a pentagonal ra-diator and a stacked rectangular parasitic element. ,e dualcircularly polarized (DCP) microstrip antenna presented in[12] achieves impedance bandwidth of 399MHz for C-bandapplications. ,e port to port isolation is more than 30.8 dBin the entire band with maximum isolation of 59.4 dB.

4.5

4

3.5

3

2.5

2Pe

ak G

ain

(dB)

Axi

al R

atio

(dB)

25

20

15

10

5

2.25 2.3 2.35 2.4 2.45Frequency (GHz)

2.5 2.55 2.6 2.65

Gain RHCPGain LHCP

AR RHCPAR LHCP

Figure 13: ,e measured peak gain and axial ratio versus frequency results for both modes of dual-port, dual CP antenna with integratedSIC network.

4.5

4

3.5

3

2.5

2

1.5

Axi

al R

atio

(dB)

-80 -60 -40 -20 0 20Theta (Deg.)

40 60 80

RHCPLHCP

Figure 14: ,e measured axial ratio versus theta results for validation model of dual-port, dual CP antenna with integrated SIC network.

8 International Journal of Antennas and Propagation

Although the reported antennas in [11, 12] have achievedmore impedance bandwidths compared to our proposedantenna, the peak isolation performance of our antenna ismuch better than that of both antennas. ,e DCP antennabased on the field transformation (FT) method is presentedand reported in [13]. For this antenna, the recorded interportisolation is 15.2 dB at 2.42GHz. Our proposed DCP antennaoffers more impedance bandwidth and peak isolationcompared to those achieved by antenna in [13]. Similarly,the peak interport isolation performance of our antenna ismuch better than designs reported in [14–21].

,e proposed dual CP antenna with high interportisolation can be used in single (monostatic) antenna-basedtransceiver architecture to realize single-channel full-duplexor in-band full-duplex (IBFD) communication. For suchapplications, dual CP characteristics of RF signals in forwardand reverse links will offer propagation domain isolation for

two-way wireless communication links. For instance, forforward link, transceiver 1 will transmit with RHCP andtransceiver 2 receives with RHCP. Conversely, for reverselink, transceiver 2 will transmit with LHCP and transceiver 1receives with LHCP. For such configuration, both links areisolated in propagation domain through polarizationdiversity.

5. Conclusion

A single-layered, trimmed corner, two-port, dual circularlypolarized (CP) 2.4GHz patch antenna has been presentedwhere improved interport isolation has been achievedthrough externally employed single-tap SIC circuit. ,eemployed isolation technique is based on signal inversionmechanism to suppress the leakage from Tx port to Rx port.,e presented dual CP antenna with high interport isolation

Gai

n (d

B)

-80 -60 -40 -20 0 20Theta (deg.)

40 60 80

LHCP mode co-polLHCP mode x-pol

RHCP mode co-polRHCP mode x-pol

5

0

-5

-10

-15

-20

-25

Figure 15:,emeasured 2D radiation patterns for co- and cross-polarization levels versus theta for prototype of dual-port, dual CP antennawith integrated SIC network.

Table 1: ,e comparison of isolation performance of presented antenna with previously reported bi-port, dual circularly polarizedantennas.

Ref. designs Peak isolation −10 dB bandwidth[1] 23 dB Not stated[3] 15.7 dB Not stated[10] (low band) 10 dB ∼150MHz[10] (high band) ∼27 dB −

[11] (band 1) Average isolation� 5.8 dB 380MHz[11] (band 2) Average isolation� 5.0 dB 770MHz[12] ∼60 dB 399MHz[13] ≥15.2 dB 50MHz[14] 35 dB 200MHz[15] 45 dB 1500MHz[16] 50 dB 85MHz[17] 36 dB 1340MHz[18] 20 dB 300MHz[19] 20 dB 150MHz[20] 45 dB 80MHz[21] 25 dB 900MHz�is work 72 dB 90MHz

International Journal of Antennas and Propagation 9

performance is an attractive solution to be used as feedantenna for S-band satellite dishes. Moreover, the design canbe scaled accordingly to work at other satellite frequencybands. ,e isolation or SIC bandwidth of the presentedantenna can be improved through two-tap SIC circuits, andthe proposed antenna can be used effectively for 2.4GHz in-band full-duplex wireless applications for simultaneous in-band transmit and receive operation. ,is will offer im-proved spectral efficiency or throughput compared toconventional time division and frequency division duplex-ing techniques for bidirectional wireless communicationlinks. Moreover, the gain of the antenna can be enhancedthrough improvement in radiation efficiency by using somesubstrate with low loss. For instance, as stated in [22], theradiation efficiency is improved from 50% to 88% for tanδ isreduced from 0.02 to 0.001. ,is will offer approximately3 dB additional gain for the proposed antenna. Such low losssubstrate will result in minor reduction in impedancebandwidth of proposed dual CP antenna. Moreover, theproposed antenna can be deployed in array configuration toachieve high gain levels.

Data Availability

,e data used to support the design and validation of thepresented antenna are available from the correspondingauthor upon request.

Conflicts of Interest

,e authors declare that they have no conflicts of interest.

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