Undesired Radiation Suppression Technique with Adaptive ...

Undesired Radiation Suppression Technique withAdaptive Control for Distributed Array Antenna

Systems in Mobile EnvironmentHideya So,Member, IEEE, Kouhei Suzaki,Non-member, and Daisuke Goto,Non-member

Abstract—We have proposed a distributed array antenna(DAA) system for high-speed satellite communications. The DAAsystem uses multiple small tracking antennas and combinesthe transmission signals in-phase to increase the antenna gain.DAA system has a problem that the undesired radiation at thesidelobe direction increases as the antenna gain at the main lobedirection increases. In the mobile environment, the conventionaltechnique can suppress the undesired radiation in the limitedcondition because of changing the direction of the undesiredradiation according to the movement of the mobile station. Thispaper proposes a DAA technique that suppresses the undesiredradiation by setting a transmission plate at each antenna apertureand moving them via adaptive control. The transmission plateconsisting of a metal patch or slot retransmits electromagneticwaves and changes the amplitude and phase of the waves. Tochange the radiation patters of each antenna, the transmissionplate rotates according to movement of the mobile station. Aftercombining these changed signals, the adaptive control selects therotate angle of the transmission plate to decrease the undesiredradiation at the sidelobe direction. The antenna gain on the mainlobe direction after combining is achieved with lower loss becausethe insertion loss through the transmission plate is smaller. Theproposed technique offers more than2.4 dB improvement withthree antennas and more than3.5 dB improvement with fourantennas assuming each consists of8× 8 patches.

Index Terms—Distributed array antenna (DAA) system, sup-pression of undesired radiation, mobile environment, transmis-sion plate, frequency-selective surfaces.

I. I NTRODUCTION

Greater capacity is being demanded from broadband satel-lite systems [1]. Satellite communication is especially impor-tant over wide ocean areas, which are not supported by land-based terrestrial networks. High-speed satellite communicationservices are generally realized by using high gain antennasto increase the equivalent isotropically radiated power (EIRP)and the carrier to noise power ratio (CNR). Increasing theantenna aperture can improve the antenna gain, but antennaweight and volume are increased disproportionately, and smallvessels have no space for large antennas. We proposed the

Manuscript received April 02, 2020; revised April 29, 2020. Date ofpublication May 11, 2020. Date of current version May 11, 2020.

H. So and K. Suzaki are with the NTT Network InnovationLaboratories, NTT Corporation, Japan, e-mails: [email protected],[email protected].

D. Goto is with the NTT Access Network Service Systems Laboratories,NTT Corporation, Japan, e-mail: [email protected].

Digital Object Identifier (DOI): 10.24138/jcomss.v16i2.1044

distributed array antenna (DAA) system; it combines multiplesmall antennas to create a larger virtual antenna aperture [2].

A DAA system has multiple small tracking antennas anda DAA controller. DAA system synthesizes transmitted andreceived signals of the multiple small antennas to establish onelarge virtual aperture antenna that offers high EIRP and highCNR. DAA system has two other major advantages. First isantenna diversity, which offers improvements in rain margin,and significant redundancy by the use of multiple antennas.Second advantage is the easy installation made possible by theuse of small antennas as space is limited on vessels, planesand buildings.

In DAA system, the distance between antennas could bemore than one wavelength and multiple grating lobes aregenerated. Each grating lobe increases the amplitude in thesidelobe direction. Therefore, high antenna gain on the side-lobe directions creates undesired radiation. When anothersatellite lies in the sidelobe direction, the undesired radiationinterferes with the other satellite [3]. It is necessary to reducethe transmission power to reduce interference to give to othersatellites. However, the gain of DAA is not achieved when thetransmission power decreases. Clearly the undesired radiationin the sidelobe direction must be decreased. Using a lowsidelobe antenna is one approach, but the sidelobe value andthe antenna size have a trade-off relationship. Since DAAsystem uses multiple small antennas, low sidelobe antennasare not suitable.

Adaptive arrays and an antenna placement technique havebeen proposed to suppress the undesired radiation for smallantenna array systems [4]–[8]. The adaptive array approach[4]–[6] controls the amplitude and phase of the transmit-ted signals so as to set nulls on sidelobe directions butprior information as to the sidelobe directions is necessary.Furthermore, suppressing the undesired radiation depressesthe antenna gain on the main lobe direction. On the otherhand, the antenna placement approach cuts the grating lobesby careful placement of the antennas. One technique usesirregular antenna spacing to disperses the grating lobe [7].Another technique places the antennas so as to match the nullof the array response vectors and the peak of one antenna [8].Unfortunately, these techniques assume a fixed environment.In mobile environments, the direction of the mobile stationto the receiver is continually changing, which renders thesetechniques ineffective.

JOURNAL OF COMMUNICATIONS SOFTWARE AND SYSTEMS, VOL. 16, NO. 2, JUNE 2020 163

1845-6421/06/1044 © 2020 CCIS

DAAController

MODEM

…

In-Phase CombiningAntenna 1

Antenna N

Receiver Antenna

…

Fig. 1. Concept of DAA system.

This paper proposes the use of adaptively controlled trans-mission plates to suppress the undesired radiation when DAAsystem is used in a mobile environment. The plate transmitselectromagnetic waves only in a specific band and can controlthe amplitude and phase of the waves by altering the incidentangle of the plate to the waves. The transmission plate isrealized as a frequency-selective surface [9]. The transmissionplate is set on the aperture of each antenna and rotated so thatthe radiation pattern of the antenna becomes asymmetrical.The undesired radiation is suppressed by combining the arrayof asymmetrical patterns. The adaptive control rotates thetransmission plate according to the movement of the mobilestation. The proposed technique can suppress the undesiredradiation with lower loss of the antenna gain on the main lobedirection because of controlling the transmission plate withoutthe antenna placement or the adaptive array.

The rest of this paper is organized as follows. Section IIpresents DAA system concept and the problems raised by mo-bile environments. Section III describes the proposed scheme.Computer simulation results are shown in Section IV. Finally,the paper is concluded in Section V.

II. D ISTRIBUTED ARRAY ANTENNA (DAA) SYSTEM

A. Concept of DAA System

Fig. 1 shows an application image of DAA system. DAAsystem consists of multiple small tracking antennas, an DAAcontroller, and a modem. The DAA controller is placedbetween the modem and the antennas. At the transmitter side,the DAA controller divides the transmitted signal intoNstreams and controls the phase and amplitude of each antennaappropriately to realize spatial in-phase combining at receiverantenna. At the receiver side, the DAA controller combinesall received signals appropriately to maximize the CNR. DAAsystem offers both easy installation and significant CNR andEIRP improvements. It also offers inherent redundancy, if oneantenna fails, the communication service is supported by theother antennas.

B. Issue of DAA System: Increasing in Undesired Radiation

DAA system has a problem that the undesired radiationincreases when the antenna gain at main lobe increases as theantenna gain at sidelobe increases.θ is defined as a directionof the receiver. Then-th antenna is set to(xn, yn). En(θ, φ)

Antenna 1

Antenna 2 Antenna 3

X

Y

Antenna 1Antenna 2

Antenna 3

Receiver Receiver

Move

θ1

θ2

(a) Configuration 1 (θ = θ1) (b) Configuration 2 (θ = θ2)

Fig. 2. Increasing of undesired radiation by direction angle change of mobilestation.

is defined as an array response vector at then-th antenna inazimuth angle,φ (−180 ≤ φ ≤ 180), and can be expressed as

En(θ, φ) =2π

λ(xn cos(θ − φ) + yn sin(θ − φ)) . (1)

gn(φ) is defined as the radiation pattern of then-th onetracking antenna. The array combining pattern,G(θ, φ), isdefined as

G(θ, φ) =

N∑

n=1

gn(φ)En(θ, φ). (2)

The DAA controller controls these vectors to realize in-phase combining. When DAA is applied to the fixed stationenvironment, thatθ is static, the optimization of the antennaplacement can decrease the undesired radiation [7], [8]. On theother hand, in mobile station environment, the optimization ofthe antenna placement cannot suppress the undesired radia-tions because the antenna placement according to the receivedantenna changes by moving. In other words,En(θ, φ) changesby changing the path length at each antenna when the mobilestation moves. In mobile station environment,θ is re-definedas the mobile station angle.

An example of increasing undesired radiation by changingmobile station environment is shown. In this case, the examplehas three antennas (N = 3) for DAA system. Fig. 2 shows theplacement of three antennas. The antenna placement changesby the mobile station moving. Fig. 3 shows the sum ofarray response vectors

∑N

n=1En(θ, φ), the radiation pattern

of one tracking antenna, and the array combining radiationpattern of each configuration. In configuration 1 (θ = θ1),∑N

n=1En(θ, φ) at φ = 15◦ is null, that the radiation pattern

of one antenna is the first sidelobe. So the undesired radiationis decreased after array combining in Fig. 3 (c). However,in configuration 2 (θ = θ2),

∑N

n=1En(θ, φ) is not null at

φ = 15◦. Note that the relative antenna placement of eachantenna is hold. The array combining radiation pattern atφ = 15◦, that is the undesired radiation, increases by changingthe antenna placement in configuration 2. This paper proposesthe suppression technique of the undesired radiation in themobile environment, which add on the existing antenna.

III. PROPOSAL: ADAPTIVE CONTROL OFTRANSMISSION

PLATE FOR DAA SYSTEM

Fig. 4 shows the concept of the proposed method. Themobile station hasN tracking antennas,N transmission plates,

164 JOURNAL OF COMMUNICATIONS SOFTWARE AND SYSTEMS, VOL. 16, NO. 2, JUNE 2020

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-5

0

-10 -5 0 5 10 15 20 25 30Rela

tive A

mplit

ude,

φ (deg.)

En(θ

, φ)

(dB

)n =

1

N Σ

Configuration 1 (θ1)


(a) Sum of array response vectors,∑

N

n=1En(θ, φ)

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-10

0

-10 -5 0 5 10 15 20 25 30

Re

lative

Am

plit

ud

e,

gn(φ

) (d

B)

φ (deg.)

(b) Radiation pattern of one tracking antenna,gn(φ)

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-10

0

-10 -5 0 5 10 15 20 25 30

Rela

tive A

mplit

ude,

G(θ

, φ)

(dB

)

φ (deg.)

Undesired Radiation is Increased



(c) Array combining radiation patterns,G(θ, φ)

Fig. 3. Increasing of undesired radiation by direction angle change of mobilestation.

and a control unit for each transmission plate. The controlunit rotates its transmission plate, which is placed in front ofthe antennas aperture, to suit the mobile stations movements.As the plate we use a frequency-selective surface (FSS) [9]consisting of a periodically structured metal patch or slot. Theincident angle of the FSS relative to the aperture, changedby rotating the plate, changes the phase and amplitude of thetransmission wave. This changes the radiation pattern of oneantenna,gn(φ). The incident angles of the transmission platesare decided so as to minimize the undesired radiation afterarray combining.

An example explains a principle of the undesired radiationsuppression. Fig. 5 shows the radiation patterns of one antennawith and without the transmission plate.p1(φ) is the radiationpattern without the transmission plate andp2(φ) is the radi-ation pattern with the transmission plate. The first sidelobe

DAA Controller

MODEM

…

Antenna 1 Antenna NAntenna 2

Control Unit for Transmission Plate

Information of Mobile Station Condition

… …

Fig. 4. Concept of suppression technique which uses movable transmissionplate.

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-10

0

-10 -5 0 5 10 15 20 25 30

Re

lative

Am

plit

ud

e (

dB

)

φ (deg.)

p1(φ)

p2(φ)

Fig. 5. Radiation patterns of one antenna with and without transmission plate.

of p2(φ) is decreased than that ofp1(φ). In the configuration2 (Fig. 2 (b)), the antenna 1 usesp2(φ) (g1(φ) = p2(φ))and others usesp1(φ) (g2(φ) = g3(φ) = p1(φ)). The arraycombining radiation pattern is shown in Fig. 6. The undesiredradiation atφ = 15◦ is decreased. The control unit choosesthe most suitable radiation pattern every antennas accordingto the mobile station angleθ.

There is a table that expresses the relationship between theundesired radiation after combining and the rotation angle ofeach transmission plate in advance. The proposed techniqueselects the rotation angles from the table according to the mo-bile stations relative position. Note that the proposed techniquecan be combined with the conventional techniques shown in

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0

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Rela

tive A

mplit

ude,

G(θ

, φ)

(dB

)

φ (deg.)


Conventional

Proposal

Fig. 6. Array combining radiation patterns.

H. SO et al.: UNDESIRED RADIATION SUPPRESSION TECHNIQUE WITH ADAPTIVE CONTROL 165

X Y

Z

Transmission Plate n (FSS)

Patch Array Antenna n

Z

Y

0.29λ0.67λ

0.2

9λ

0.6

7λ

(a) Perspective view

Patch Array Antenna n

s

αnX

Y

Transmission Plate n (FSS)

Rotation

(b) Top view

Fig. 7. 8×8 patch array antenna configuration employing transmission plate.

0.03λ0.33λ

0.42λ

0.0

3λ

0.3

3λ

0.4

2λ

Slot

Metal

…

Fig. 8. Transmission plate.

[4]–[7].

IV. PERFORMANCEEVALUATION

Simulations were conducted to verify the effectiveness ofthe proposal. First, an electromagnetic field analysis was per-formed to calculate the radiation patterns of one antenna withthe transmission plate. Next, the array combining radiationpatterns were simulated using the array response vector of eachantenna and the radiation patterns calculated in a preliminarystep [11]. DAA system employs the patch array antenna asthe one antenna because the transmission plate can be placednear the aperture of the antenna. In this paper, DAA systemuses three or four antennas, which are the8 × 8 patch arrayantennas.

A. One Antenna Design

Fig. 7 shows a8 × 8 patch array antenna with movabletransmission plate. The patch array antenna consists of64patches, see Fig. 7 (a) for details.λ is a wavelength of theresonant frequency. The patch array antenna is made on a

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0 30 60 90-180

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0

60

120

180

Tra

nsm

issio

n A

mplit

ude (

dB

)

Tra

nsm

issio

n P

hase (

deg.)

Incident Angle (deg.)

Fig. 9. Transmission characteristics of transmission plate.

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0

10

20

30

-180 -150 -120 -90 -60 -30 0 30 60 90 120 150 180

An

ten

na

Ga

in (

dB

i)

φ (deg.)

without Transmission Platewith Transmission Plate

(s = 1.0λ, αn = 45 deg.)with Transmission Plate

(s = 1.0λ,

αn = 0 deg.)

Fig. 10. Radiation pattern of one antenna with and without transmission platein the horizontal plane.

print circuit board, and that relative permittivity is 2.6. Thearray is fed from the backside of the antenna element. Thetransmission plate and the patch array antenna lie on thesame X-axis. The distance between the transmission plate andthe patch array antenna is defined ass. The transmissionplate rotates around the Z-axis at the center of the plate asshown in Fig. 7 (b), and changes the radiation pattern in thehorizontal plane. The rotation angle ofn-th transmission plateis defined asαn. The rotation control unit is not shown inFigs for simplicity. Details of the transmission plate, whichis the 5 × 5 slots, are shown in Fig. 8. Fig. 9 shows theamplitude and phase characteristics of the transmission plateversus the incident angle. It can be seen that the insertionloss through the transmission plate is negligible in the frontdirection. However, the insertion loss increase and the phasechanges as the incident angle is increased.

Fig. 10 shows the radiation patterns of one antenna with andwithout the transmission plate.s was set to1.0λ, andαn wasset to0◦ and45◦ when the antenna has the transmission plate.Each VSWR is less than 1.5. The peak gain of the radiationpattern with the transmission plate atαn = 0◦ is equal as thatof the radiation pattern without the transmission plate. Theinsertion loss of the transmission plate is negligible because


of αn = 0◦. The transmission plate atαn = 0◦ changes thesidelobe from that of the antenna without the transmissionplate. On the other hand, the peak gain decreases 0.5 dBwhen the transmission plate rotated,αn = 45◦ because thetransmission plate has loss for electromagnetic waves by thediagonal incidence.

Fig. 11 shows the relationship between the power of eachsidelobe andαn. s also was set to1.0λ. The horizontal axis isthe index of each sidelobe starting from the lobe immediatelyadjacent to the main lobe. The transmission plate changes theasymmetrical pattern byαn. Fig. 12 plots the power of thefirst sidelobe as a function ofs whenαn is 45◦. αn cannotbe set more than45◦ when s is less than1.0λ because thetransmission plate touches the antenna element. Therefore,s

values less than1.0λ, are excluded. The power of the sidelobeincreases ass increases because the transmission plate scattersthe electromagnetic waves. In this paper,s is set to1.0λ sothat the power of the first sidelobe is minimized.

6.0

6.5

7.0

7.5

8.0

8.5

9.0

-4 -3 -2 -1 4 1 2 3

Sid

elo

be

Le

ve

l (d

Bi)

Sidelobe Number

12 3 4

-1-2-3-4

Sidelobe Number

φ

:αn = 15 deg.

:αn = 30 deg.

:αn = 45 deg.

Fig. 11. Relationship between the sidelobe level and rotary angle, αn.

6

8

10

12

14

16

0 1 2 3 4 5

Sid

elo

be

Le

ve

l a

t 1

st

Sid

elo

be

(d

Bi)

Distance between Transmission Plate and Antenna, s (/λ)

αn = 45 deg.

Fig. 12. First sidelobe level as a function of the distance,s, when αn is 45◦.

B. Suppression Effect of Undesired Radiation at Array Com-bining

Fig. 13 shows the antenna placement with three and fourantennas. These antennas are set at equal distances on the

circumference with radius ofr. Each antenna is the sameas that detailed in the previous section. Seven plate rotationangles were examined by changingαn from −45◦ to 45◦ insteps of15◦. It is assumed that the mobile station has a receiverantenna withθ = 0◦. αn at each antenna is chosen from theall combinations so that the undesired radiation is minimized.For simplicity, the elevation angle was kept constant at0◦.

The suppression value,GU (θ), is defined as the differencebetween the peak gain atφ = 0◦ and the value that ismaximum except the main lobe,10◦ ≤ |φ| ≤ 180◦. GU (θ)is shown below,

GU (θ) = G(θ, 0)− max10◦≤|φ|≤180◦

G(θ, φ). (3)

The undesired radiation is small so thatGU (θ) is large.

Antenna 1Antenna 2

Antenna 3

θ

Reciever120 deg.

r

X

Y

Mobile Station

(a) 3 antennasAntenna 1Antenna 2

Antenna 4

θ90 deg.

r

X

Y

Antenna 3

Reciever

(b) 4 antennas

Fig. 13. Antenna placement.

Fig. 14 shows an array combining radiation pattern of threeantennas. For comparison, the performance of the conventionalapproach, which has no transmission plate and no adaptivecontrol, is shown. The radius of antenna placement,r, isassumed to be5.5λ. 5.5λ is almost the smallest placementdistance because the antenna size is approximately5.2λ. Themobile station angle,θ, is set to37◦ when GU (θ) of theconventional is worst case. The peak gain is decreased0.5 dBby the adaptive control of the transmission plates. However,the undesired radiation atφ = 15◦ is decreased3.2 dB. Theproposal offers an improvement of2.7 dB in consideration ofthe gain loss.

Fig. 15 (a) showsGU (θ) of three antennas as a functionof mobile station angle,θ. GU (θ) exhibits periodicity because


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30

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-180 -150 -120 -90 -60 -30 0 30 60 90 120 150 180

Am

plit

ude,

G(θ

, φ)

(dB

i)

φ (deg.)

Proposal

Proposal

0.5 dB Decreased

3.2 dB Decreased

Conventional

G(θ

, φ)

(dB

i)0

10

20

30

40

-10 0 10 20 30φ (deg.)

N = 3, r = 5.5λ, θ = 37 deg.

Conventional

(no Transmission Plate

and no Adaptive Control)

Fig. 14. Comparison of array combining radiation pattern whenGU (θ) ofconventional is worst case.

of the circumferential antenna placement. Fig. 15 (b) showsthe characteristics for one period;θ ranges from 0◦ to 60◦.The maximum transmission power is decided by the maximuminterference that the transmitter imposes on the other receiver.Therefore, suppression performance is evaluated from the min-imum GU (θ) that is the worst case. The proposed techniqueimproves the undesired radiation regardless ofθ and offers animprovement of2.4 dB. The radius of the antenna placement,r, is changed. Fig. 16 showsGU (θ) with three antennas asa function ofθ when r is 10λ. The proposed technique cansuppress the undesired radiation regardless ofθ. The minimumGU (θ) of the proposal is improved2.9 dB than that of theconventional.

Finally, the impact of the number of antennas was con-firmed. Fig. 17 plots the minimumGU (θ) for each antennanumber as a function ofr. The proposed technique of eachantenna number suppresses the undesired radiation comparedto the conventional approach for all antenna numbers exam-ined. The proposed technique with four antennas offers animprovement3.6 dB whenr is 10λ, and the improvement isbigger than that with three antennas. Each minimumGU (θ)of the proposed technique has the same characteristics withoutdependence on the number of antennas because the optimalvalue is chosen inαn every antenna.

V. CONCLUSIONS

This paper has proposed an undesired radiation suppressiontechnique for DAA systems in mobile environments. Theproposed technique sets a movable transmission plate at eachantenna aperture and controls plate angle to suit the mobilestations relative position. DAA system with an8 × 8 patcharray antenna as one antenna was assumed. These antennaswere set at equal distances on the circumference. The proposalwas found to offer more than2.4 dB greater suppression withthree antennas and more than3.6 dB suppression with fourantennas when the radius of the antenna placement was10λ.The proposal had no characteristics change by the number ofantennas. The rotary angle design, which does not choose fromall combinations, is the subject for future study.

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0 30 60 90 120 150 180 210 240 270 300 330 360

Su

pp

ressio

n V

alu

e o

f U

nd

esire

d R

ad

iatio

n,

GU

(θ)

(dB

)

Mobile Station Angle, θ (deg.)

Proposal

Conventional

(no Transmission Plate and no Adaptive Control)N = 3r = 5.5λ

(a) 0◦ ≤ θ ≤ 360◦

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14

15

16

17

18

19

20

21

0 10 20 30 40 50 60


Proposal

N = 3r = 5.5λ

Su

pp

ressio

n V

alu

e o

f U

nd

esire

d R

ad

iatio

n,

GU

(θ)

(dB

)

Conventional

(no Transmission Plate and no Adaptive Control)

2.4 dB

(b) 0◦ ≤ θ ≤ 60◦

Fig. 15. Undesired radiation value as a function of mobile station angle,θ,with 3 antennas whenr is 5.5λ.

13

14

15

16

17

18

19

20

21

0 10 20 30 40 50 60


Proposal

N = 3r = 10λ

Su

pp

ressio

n V

alu

e o

f U

nd

esire

d R

ad

iatio

n,

GU

(θ)

(dB

)

Conventional (no Transmission Plate and no Adaptive Control)

2.9 dB

Fig. 16. Undesired radiation change as function of mobile station angle,θ,with 3 antennas whenr is 10λ.


13

14

15

16

17

18

0 5 10 15 20 25 30

Radius, r (/λ)

Proposal

N = 3N = 4

Conventional

(no Transmission Plate and

no Adaptive Control)

Min

imum

Suppre

ssio

n V

alu

e o

f

Undesired R

adia

tion, m

in G

U(θ

) (d

B)

0 <

θ <

36

0

Fig. 17. Minimum of undesired radiation as a function ofr.

REFERENCES

[1] O. Vidal, G. Verelst, J. Lacan, E. Alberty, J. Radzik, and M. Bous-quet, “Next generation high throughput satellite system,”2012 IEEEFirst AESS European Conf., pp. 1–7, Oct. 2012. doi: 10.1109/ES-TEL.2012.6400146

[2] K. Suzaki, Y. Suzuki, and K. Kobayashi, “A novel earth station an-tenna concept for Ku-band mobile satellite communication systems —Distributed array antenna and key technologies—,”29th AIAA ICSSC-2011, Nov.-Dec. 2011. doi: 10.2514/6.2011-8051

[3] F. Yamashita, Y. Suzuki, D. Goto, K. Suzaki, H. So, and K. Kobayashi,“Research and development of technologies on distributed array antennasystems,” in Proc.IEICE Conf. 2015, B-3-15, Sept. 2015.

[4] P. W. Howells, “Intermediate frequency sidelobe canceller,” U. S. Patent,no. 3202990, Aug. 1965.

[5] R. T. Compton, “Wideband interference cancellation in adaptive sidelobecancellers,” IEEE Trans. on Aerospace and Electronic Systems, vol.AES-19, no. 6, Nov. 1983. doi: 10.1109/TAES.1983.309403

[6] M. M. Khodier and C. G. Christodoulou, “Linear array geometrysynthesis with minimum sidelobe level and null control using particleswarm optimization,”IEEE trans. Antennas Propag., vol. 53, no. 8, pp.2674–2679, Aug. 2005. doi: 10.1109/TAP.2005.851762

[7] O. Mizokami, T. Nakazawa, and M. Shinriki, “A Study on an arrange-ment spaces for a non-uniform array in suppressing gratinglobe,”IEICETrans. Commun., vol. J83-B, no.1, pp.141–143, Jan. 2000.

[8] D. Goto, F. Yamashita, K. Suzaki, H. So, and K. Kobayashi, “A proposalon the offset antenna arrangement technique to improve transmittingEIRP in the distributed array antenna systems,” in Proc.IEICE Gen.Conf. 2015, B-1-220, March 2015.

[9] B. A. Munk, Frequency selective surfaces: theory and design,Wiley-Interscience Publication, 2000.

[10] ANSYS HFSS, http://www.ansys.com/.[11] D. Goto, F. Yamashita, K. Suzaki, H. So, Y. Suzuki, and K. Kobayashi,

“Experimental validation of a practical method of estimating distributedarray antenna Patterns,”JC-SAT 2015, Oct. 2015.

[12] J. D. Kraus, Antennas third edition,Mc Graw Hill, 2002.

Hideya So received the B.E. degree from TokyoUniversity of Science, Japan, in 2009, and the M.E.degree from Tokyo Institute of Technology, Japan, in2011, respectively. He joined NTT Access NetworkService Systems Laboratories, NTT Corporation,in 2011. He engaged in has researched on high-reliability radio access, base station antennas, andadaptive arrays for the future wireless access sys-tems. He currently works for NTT West Corpora-tion. He received the IEICE Radio CommunicationSystems (RCS) Active Researcher Award in 2011,

the IEICE Young Researcher’s Award in 2016, and the IEICE Best PaperAward in 2016. He is a member of the IEICE and IEEE.

Kouhei Suzaki received the B.E and M.E degree inelectrical engineering from Tokyo University of Sci-ence, Tokyo, Japan in 2007 and 2009, respectively.In 2009, he joined NTT Access Network ServiceSystems Laboratories. Since then he has been en-gaged in research on signal processing of adaptivearray antenna and the Satellite Earth Station. He isa member of IEICE.

Daisuke Goto received the B.E. degree in systemengineering from Shizuoka University and the M.E.degree in electrical engineering and computer sci-ence from Nagoya University, Japan, in 2010 and2012, respectively. In 2012, he joined NTT AccessNetwork Service Systems Laboratories, Japan. Hiscurrent research interest is satellite communicationtechniques.


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