Design and Implementation of a Quasi-Orthogonal Switching Beam-Former for Triangular Arrays of Three Radiating Elements

Transcription

1 Design nd Implementtion of Qusi-Orthogonl Switching Bem-Former for ringulr Arrys of hree Rditing Elements Jvier Grcí-Gseo rujillo, Alvro Novl Sánchez de oc, Igncio Montesinos Ortego, José Mnuel Fernández González, nd Mnuel Sierr Pérez Abstrct An innovtive switching multi-bem network for tringulr rrys of three rditing elements is proposed. his novel network provides three orthogonl bems in desired elevtion ngle nd fourth one in the brodside steering direction. he network is composed of four-port 3-dB qudrture hybrid power couplers nd fixed phse shifters. In this pper, reltion between network components, rditing element distnce nd bem steering directions is shown. Appliction of the proposed dissiptive network to the tringulr cell of three double stcked ptches of 1.7 GHz nd 60 bemwidth tht integrtes the intelligent ntenn GEODA with n rry distnce of 0.56A is exhibited. Mesured scttering prmeters of the network re compred with both, theoreticl nd simulted scttering mtrices, vlidting the expected behvior. Besides, by combining two complementry single proposed networks, mtrix tht supplies six orthogonl bems in given elevtion ngle nd seventh one in the brodside steering direction hs been built. Moreover, the whole system, dissiptive network with GEODA cell rry, hs been mesured in the nechoic chmber of the Rdition Group t echnicl University of Mdrid, demonstrting successful performnce. Index erms Adptive rrys, bem steering, multibem ntenns, phsed rrys. I. INRODUCION FROM the beginning of telemetry, trcking nd commnd (&C) systems, mechnicl scnning ntenns hve been employed t ground sttions. As it is well known, this technique is not only sensitive to grvity nd mechnicl filure, but lso slow, incresing the totl cost of the system nd mking simultneous stellite communictions infesible. he use of electroniclly scnned ntenn rrys overcomes these limittions, llowing much fster multi-bem scns without physicl ntenn rottion [1], []. hese types of systems tht use informtion from the link environment to set the proper bem shpe re clled intelligent rchitectures [3], [4]. In order to improve the ground sttion performnce, mny studies hve been crried out in the field of electronic scnning systems, in which lrge rrys composed of thousnd of rditing elements hve been considered [5]. Electronic steering technique is bsed on the control of the reltive mplitude nd phse of the signl ssocited with ech ntenn tht composes the whole rry. he reltive signl cn be djusted by using digitl signl processing lgorithms, e.g., MUSIC [6] or ESPRI [7], or plcing bem-forming circuits inside the hrdwre ntenn, e.g., phse shifters [8] or switched networks [9]. Nowdys, softwre/hrdwre hybrid rchitectures re gining specil interest becuse of their verstility. Generlly, these huge rry structures re divided into subrrys bsed on unitry cells of t lest three rditing elements to reduce not only post-processing dt time but lso its cost [10] [1]. he unitry cell rdition pttern, the combiner/divider cell circuit nd the post-processing dt lgorithm will define the whole system cpbilities. his segmenttion my reduce the totl number of required ctive circuits, such s mplifiers or phse shifters [13], decresing totl cost nd improving post-processing dt efficiency. Usully, this type of ntenn performs hrdwre bem steering tht selects the willing communiction direction re nd signl dt processing lgorithm tht improves the desired signl to interfering signl/noise rtes. herefore, the study of structures tht provide multiple bems in different sptil rnges relted to ech sub-rry cell is needed. he number of rditing elements composing the unitry cell nd its distribution stte the bsic bem scnning shpe. A tringulr cell of three rditing elements is the simplest wy to obtin plnr scnner. In this pper, new multibem network configurtion tht provides three orthogonl bems in desired 6Q elevtion ngle nd n extr one in the brodside steering direction for tringulr rry of three rditing elements will be introduced. Section II will present short introduction to the stte of rt of clssicl multi-bem networks [14], [15]. Lossless network nlysis, including originl lossless network designs [9], will be lso commented. Section III will show generl dissiptive mtrices theory s well s pplictions for rry ntenns of three rditing elements. In Section IV, the proposed finl bsic multi-bem network will be simulted, built nd mesured to the GEODA prcticl cse. Section V will present combined network tht provides six orthogonl bems in desired #o elevtion ngle nd double seventh one in the brodside direction by using two complementry proposed bsic net-

2 70 60 D> <L> C O 40 /b = 0.5; 3= /b = 0.7; 3 = /b = 1.0; 8 = 10 /b = 1.3; p = /b =1.5; 3 = ^Y I 30 ^ ^ " ^ ^ ^ ^ I 0 d) m Arry distnce d [A] ^^^^-Ss Fig. 1. (Left) ringulr cell of three rditing elements nd its orthogonl f^- Arry fctor steering direction 0 O respect to rry distnces for different bems [Azimuth xy-plne]. (Right) Coordinte System. feeding signl reltions. works. Mesurements of the whole system will be lso depicted. Finlly, Section VI will collect the conclusion drwn during the pper. II. ORHOGONAL MULI-BEAM FORMING NEWORKS FOR RIANGULAR ARRAYS One of the most importnt tsks in phsed rry ntenn is to design the bem-forming network (BFN). A BFN essentilly combines/divides properly the signl of/to ech rditing element compounding the rry in order to produce the desired bem. Most common types of BFNs re presented in [13], where Butler mtrix [16], Blss network [17], Rotmn lens [18] nd mny more re explined. Mny studies hve been developed in order to overcome the limittions of these useful networks. As n exmple, switching network tht genertes four bems for three liner rditing elements is presented in [19]. Finl network presented in this pper is bsed on Butler mtrix modifictions. he behvior of BFN is chrcterized by its scttering mtrix. As presented in [9], when lossless nd reciprocl network with dpted nd isolted bem nd rry ports is considered, vectors relted to the columns of ech trnsmission nd reception mtrices re orthonorml to ech other. Hence, the number of bem nd rry ports must be the sme; the output power must be equl to the input power; nd its scttering mtrix vectors must be orthogonl, ensuring isoltion between different bems. Assuming three rditing elements locted over vertices of n equilterl tringle in the xy-plne with d side length s in Fig. 1, the reltion between the loction of the rditing elements nd the rry signl is shown in (1) nd () 3 AF(0, <t>) = ^ A i e ~ ji e ~ jk * ri cell. (!) =i -krr ptch i - ptch i = - kfr ptch - ptc h - kfr ptch3 - OL p tch3- () he lossless scttering prmeters of network ssocited with tringulr cell of three rditing elements tht provides three orthogonl bems in desired 6Q elevtion ngle must stisfy the condition of dding contributions of ech rry element in the desired steering direction. Hence, it is shown tht desired bem is obtined when reltions between rry port signls re where ptchi, Beml ^ptch,beml ^^ Sptch3,Beml =be~ 3l -! /? = v^^sin(6j 0 ). wo dditionl orthogonl bems re obtined by rotting signl reltions between rry ports. Ensuring orthogonl excittion vectors by imposing (), is obtined, sin(0 o ) = y/sird rceos - ) (6) b J Bem steering direction f?o, depends on both, rry element distnce d nd feeding signl reltion between elements in mplitude /b nd phse 3. Fig. shows the steering elevtion direction f?o of the rry fctor for different d, /b nd /?. As distnce between elements d or reltion b/ increse, bem steering direction 6Q rise closer to brodside (f?o = 0 ). Once nlysis hs been performed, the hrd tsk is to find structures tht fulfill the desired behvior. Different lossless schemes of three bem ports by three rry ports bsed on hybrid couplers nd fixed phse shifters hve been studied, [9]. Intrinsic fetures of orthogonl lossless networks limit the number of provided bems to the number of rditing elements nd impose the reltion between those bems. herefore, this reserch leds to consider the possibility of using dissiptive networks, which re cpble of providing higher number of bems thn the number of rditing elements compounding the III. DISSIPAIVE NEWORK FOR RIANGULAR ARRAYS Dissiptive networks re those tht hve intrinsic losses ssocited with ech generted bem. his type of network hs no need to ccomplish bem orthogonl condition, giving greter degree of freedom to control bem steering directions. When orthogonl condition is fulfilled in ll the bems of network, the mximum rry gin is ensured due to lossless implicitness. (3) (4) (5)

3 However, when rditing elements re relted to rdiofrequency circuits in which mplifiers re found, the relevnt prmeter tht shows the qulity of the ntenn is the G/ fctor. As result, the use of dissiptive network is not restricted whenever there is n mplifier stge. In this section, four bem ports by three rry ports qusi-orthogonl dissiptive network tht genertes three orthogonl bems in desired elevtion direction 0 O nd n dditionl bem in the brodside direction is studied. o this end, four bem ports by four rry ports network with mtched rry port is nlyzed. he scttering mtrix ssocited to the dissiptive network under study is shown in (7). Brodside bem is obtined by mintining sme signl reltion between elements t rry ports (column one). hree orthogonl bems re generted s nlyzed in Section II thnks to columns two to four U (t) Fig. 3. () Scheme of 4 X 3 modify Butler mtrix, (b) GEODA cell rry fctor when the network is connected. Ech color is different bem. [S] = f f f gie> i be-i? g e^ be- j P g 3 e>» be-* 13 9i& J«4 (7) he mtched rry port gives degree of freedom, s depicted in row four of mtrix (7), with which is possible to stisfy the reciprocity lossless condition () if the whole 4x4 network is considered. his condition does not remove losses ssocited to the 4 x 3 dissiptive network but reduces them to the power bsorbed by the mtched rry port. Applying condition () to the scttering mtrix (7) is obtined 5 = l-3/ (8) gi = 1 - -b with i =[,4] (9) f (+be i P)=-g 1 g i ( 1 - i )withi =[1,] (10) {+be ifi +b- j P+b- j P) = - gi g jeh - j) with i,j = [,4] (11) Solving system (8) (11), reltion between signl rry ports re given by where = + r r = r = r I-/ + r (1) (13) (14) Losses ssocited with the network re relted to the brodside bem s 5i=l-3/ 9i=f with = [,4]. otl men losses of the 4x3 dissiptive network is Ef=iá? 1-3/ + 3/ (15) (16) (17) Fig. 4. 4x3 proposed dissiptive network. Showing tht totl men network losses re independent of its configurtion, being fourth of the totl power. he homogeneous losses cse is obtined when / = 1/, in which ech bem hs 1.5 db losses. he steering direction of the three orthogonl bems with the desired 6Q elevtion ngle depends on signl fctors, (, b), nd on the distnce between elements of the rry, (d), s sin(0 o ) \/37rd cos / + b -l\ V b J (18) Severl dissiptive networks for tringulr rrys hve been studied. It is importnt to ber in mind the fct tht the ppernce of intrinsic side lobes nd diffrction must be considered nd voided, s shown in [9], where the truncted Butler network for three rditing elements shown in Fig. 3() ws nlyzed, presenting two min lobes when it ws pplied to tringulr cell rry. Fig. 3(b) depicts expected rry fctor if the network is pplied to GEODA subrry cell. Finlly, the proposed dissiptive network tht provides three orthogonl bems in the desired steering direction Ao nd n dditionl one in brodside is shown in Fig. 4. he network is composed of four four-port 3 db 90 hybrid power couplers, four fixed phse shifters nd 0 log(i/c) db 90 power coupler. Its behvior is shown in (19) t the bottom of the next pge, thnks to its scttering mtrix.

4 o obtin the proper signl network distribution tht genertes the desired bems, the scttering mtrix of the proposed network, (19), must be mtched to the desired scttering mtrix pttern previously nlyzed, (7). After comprison, scttering prmeters of the network under study re giving by <^P \ rg[s ] = (mod [S ]) K 0 0 it c 4-3c c c c c c c c c c 4 3c c4 3c c c (0), = tn" 1/-7I^\ (1) he behvior of the network is governed by the vlue of the centrl coupler c, s shown in (0) nd (1). Reltions between network components obtined fter study re cos() = \/l c with sin() 03 ±Vc () 4>A + (3) o he sign in sin() = ±\/c determines the desired elevtion steering direction ±0o of the three orthogonl bems. In the bove nlysis, sin(cí) = +y/c hs been considered. A complementry bem-former network could be obtined by using in the study sin() \[c, s shown in Section V. Moreover, note tht </>3 nd (f>4 re fixed phse shifters not relted to the desired steering direction 6Q of the three orthogonl bems but to the reltive phses between rry ports needed to generte the different desired bems. he reltion between the desired steering direction ngle 9Q nd the phse shift between elements 3 ws given by (5). he steering direction of orthogonl bems s well s losses ssocited with ech bem depend on the coupler c s sin(0o) = tn jg -101og(l--) -lolog(ijc). (4) (5) (6) : c = 0.0;u = 0.0 / ;c = 0.1:8 = 18.4 /! c-=0;á-bb'> I :C = 0.3; = 33.' «- 0 4 ii = 0.5:0 = 45.0 : ^c = 0 8:c> = 63.4 o = 0 6:ri = 50 8 ^^c = 6.9:5 = 71.6 :c = 0.7;cf = 56.8 : :c = i.0: = Arry distnce d [^.] Fig. 5. Bem steering directions 8 0 depending on prmeters c,, nd d CO v L i 0.5 i 0.6 i c-coupler Fig. 6. 4x3 Bem losses. (Blue) Brodside bem. (Red) 9 0 steering direction. Fig. 5 shows bem steering directions #o depending on the prmeters c, nd d. Both type of losses, LQO nd LQ O ssocited with brodside nd tilted bems respectively, re lso depicted in Fig. 6. Fig. 5 presents the bem steering cpbilities of the network, showing tht for lrger rrys the possible coverge re in the system is reduced. For bem-switching ppliction, the continuous coverge of the system field-of-view is criticl design requirement, which mens tht reltive mplitudes between every bem compounding the network must be crefully nlyzed. he totl losses of the system tht must be tken into ccount re: intrinsic losses of the proposed network (Fig. 6) nd losses introduced into the tilted bems becuse of the bem width of the single element composing the ntenn rry. he importnt condition in the design is tht both losses should be blnced to provide qusi-homogeneous rdition pttern in the system [Sj A=e~ J B=\/l A-B -j(a + B) C -j(a + B) -yc -(A-B) -JVH -JV5 "^3 (-{A-B))e-rt - ^ - ^ (-j(a + B))e-M* 3\c -V~c {-JiA + B^e-i* 3 (A - B^-M* (19)

5 ABLE I SCAERING MARIX AND LOSSES OF HE 4X3 NEWORK [ AOl 0.700e' - 91s " 0.37e J,,M3z " 0.31e-J ' 51 " 0.31e J ' os3 '" A0 0305e-' OM <- 7 ' 0.31e' 0049 " 0.37e- J ' e- jo ' los '' A e-J e J '"" 68 " 0.683e-",t e J ' 057 " P ii8.r±3 0 ±3 ii.r± ii9.r±3 Losses 3% 70% 33% 3% ""Or*^ heory C^^O^ Mesurement 40 Fig. 7. Microstrip dissiptive 4x3 proposed network. field-of-view considered. Losses in softwre/hrdwre hybrid rchitectures re compensted by using mplifiers. Fig. 6 depicts tht the intrinsic network losses for the brodside bem decrese s c increses, showing tht for c-coupler smller thn 0.4 the losses forthe brodside bem will be higher thn 5 db. herefore, it is importnt to notice tht to implement proposed network with such smll c-coupler might be imprcticl since it would be very difficult to blnce such high intrinsic losses of the network. IV. IMPLEMENAION OF HE PROPOSED 4X3 NEWORK In this section, microstrip implementtion of the proposed dissiptive network is presented. he im of this section will be to vlidte tht the signl distribution provided by the network is s defined by (0) nd (1). he genertion of three orthogonl bems with 6Q elevtion ngle nd n dditionl one in the brodside direction when the designed network is pplied to tringulr cell of three rditing elements will be verified s well. For this purpose, the simple prcticl cse in which ll hybrid power couplers composing the network re four-port 3-dB qudrture couplers is ssumed. his cse is obtined when min network prmeters re c = 0.5 with = 45 (7) o simplify the implementtion nd minimize the size of the whole network, commercil four-port 3-dB qudrture hybrid power couplers (Mini Circuits QCN-5) re used. Additionl fixed microstrip trnsmission line lengths will generte required phse shifters. king (7) into (0) nd (1), the scttering mtrix ssocited to this network is mod^x] = rg[ J (8) (9) o check correct performnce, the network with idel components hs been simulted by CS Design Studio 011. Its scttering mtrix shows perfect behvior. Simulted scttering prmeters with rel mesurements of the 4x3 dissiptive network components, fixed phse shifters nd QCN db SÍ J 03 H 0 10 /fv Vw/ \v\if ' v Jr ' //xcl JL 0 3i<L~ * Phi [deg] Fig. 8. Rdition pttern simultion of the whole system, cell with proposed network, using theoreticl (blue) nd mesured (red) S-prmeters. hybrid couplers, re shown in expressions (30) nd (31). hese mesurements show good greement with expecttions, with phse error of ±4 nd n mplitude error of ±0.1 db mod [Sj vg[s ] = lJ (30) (31) he network hs been implemented in microstrip RO4350B substrte of 0.54 mm thickness s presented in Fig. 7. Fixed phse shifters nd four-port 3 db 90 hybrid power couplers (QCN-5) hve been evluted independently in order to ssure good performnce. he use of commercil chip couplers is helpful when totl network dimensions must be minimized. he network presents ±0.3 db module error nd ±5 phse error s summrized in ble I. Signl errors introduced re resonble, s it is depicted in Fig. 8, where comprtive simultion between rdition ptterns of the cell GEODA with theoreticl nd mesured S network prmeters shows low bem steering devitions. It is worth noting the use in the simultion of the previous mesured rdition pttern of the rditing element composing the GEODA cell, which consists of two stcked circulr ptches with 60 bem width [9]. his bemwidth explins not only the mismtch between fctor rry nd rdition pttern elevtion steering direction OQ, shifting from 41.9 to 3.1, but lso the increse of side lobes shown in following rdition pttern mesurements of the GEODA cell with the implemented network. Fig. 8 shows n lmost continuous coverge by using ptch element with 60 bemwidth. Moreover, the whole system, dissiptive 4x3 network with GEODA cell rry, hs been mesured in the nechoic chmber

6 () / / > /»i ' ^ ^ Mesurement mt *m m Simultion Ns! V \\l \\ U ; i 3i i i 1 \ hci [dcg] Fig. 9. Whole system, dissiptive 4x3 network with GEODA cell rry, in the nechoic chmber of the Rdition Group t UPM. i in Á^ \ ^V; of the Rdition Group t echnicl University of Mdrid s shown in Fig. 9. Mesurements confirm the genertion of one bem in the brodside steering direction with n error of ±3 nd three orthogonl bems equidistnt in zimuth 10 ± 5 with n elevtion of 3 ±, s expected, depicted in Fig. 10. he rdition ptterns ssocited with the three tilted bems present n incresed secondry lobe with pek of 5 db with respect to the min bem. Comprisons between mesured nd simulted rdition ptterns ssocited with ech bem hve shown good. Min lobe shpes nd steering directions fit properly. he three tilted bems present cceptble smooth vritions in mplitude, ± db, nd zimuth, ±7.5. hese devitions might be relted to mismtch between the built nd the simulted ptch rry structure. V. A 7 X 3 BFN BY USING COMPLEMENARY NEWORKS o find bem pttern s homogeneous s possible leds to consider the use of switching bem-formers with higher number of bems. While the number of bems provided by the network is incresed, the depointing losses ssocited with the switching between contiguous bems re reduced. In this section, new 7x3 network is proposed by combining two complementry 4x3 networks s described in Fig. 11. he prcticl implementtion is composed of the designed network in the previous section (BFN A) nd its complementry network tht genertes sme bems but rotted 180 in zimuth (BFN B). Design prmeters of BFN B re obtined by considering in the nlysis the reltion (3) hen COS(CK) = y/l c withsin(o!) = yfc. c=0.5 with = -45 fc =f + = 0. (3) (33) (34) Being the expressions governing complementry networks s follow: sin(0 o ) = 0 = ->/ * y sin(0 o ) A 1 A V3ñd tn -(y/=c) H (35) (36) (c) Í -5-11) -M -10 ft 1 /' \ ^"^^ Mesurement \ Simultion 1 ; V het [tlcg] / -0 ^^^^ Mesurement /» ^ \ Simultion ' V > 1 \\ /\ / \ f^% 1 Yp J^ f ^^^^ Mesurement f -0 r 1 ^ _ ^ «Simultion { 1 * het [deg] Fig. 10. (), (b), (c), nd (d) Mesured rdition ptterns of the bem forming network nd cell subrry GEODA by exciting All, AI, AI3, nd AI4 respectively. (Left column) Comprison between mesured (red) nd simulted (blue) rdition ptterns. Considering the cse under study, nd tking into ccount the expressions bove, it is shown the desired 180 rottion bems (3 = with BOB = 41.9 = -9 0A. (37) Losses ssocited with the BFN B re the sme s in the simple BFN A. he BFN B hs being simulted nd implemented s BFN A, obtining similr behvior s its complementry. After vlidtions, the whole 7x3 network hs being built s shown in Fig. 1. Scttering prmeters of the network hve being mesured. Scttering prmeters of the 7x3 network relted to A-input ports re similr to those shown in ble I but 3 db

7 ^n 90 3dB ^Qfi 90 3dB Ptch 03 Ptch 0 BFNA ^«n 3dB Ptch Q1 BFNB E&Q ^n Fig x 3 BFN Scheme het [deg] Fig. 1. Implementtion of the 7x3 BFN. v^v \\ v\ il if A 1 IVI i Mesurement Simultion i \ ABLE II SCAERING MARIX AND LOSSES OF HE 7X3 NEWORK Z het [deg] 1A A 3A 4A IB B 3B 4B Ptch 1-0 0AQe }0-70w 0.1e - -' e JO - 8lc 0.i e J'o-34" 0SÉ,J0.9SI 0 0^)0.85,1 04 e;o.85ít 00^ Ptch e-- f0o5, 0.e-i 16n 0.e> 0Sln 0.48e^' 03, 0i e;o.33i 0.3e'' 085I 019e;0.83n QA9ejo.<>(,, Ptch e- J ' - 66,t O^Oe - -" e- io - 01t 0leJ0.37 1l 0 e Jt)3i 1l 0.4e jos3lt 0.53e--, ' - 53,t 0.e ju8t P 116 ±1 0 ± ± ± ± 0 ± ± ±5 Losses lower due to coupler combiner/divider between complementry networks. ble II summrizes mesurements of scttering prmeters of the whole network, where is shown ±0.3 db error module nd ±5 error phse. Fig. 13() shows the mesurement of the rdition pttern of the brodside bem, nd Fig. 13(b) depicts the mesurement of the generl rdition pttern of tilted bem. Besides, min plne sections of mesured nd simulted rdition ptterns re lso presented, showing similr chrcteristics s previous network A (Fig. 10). Hence, these mesurements show successful system behvior, providing desired bems. VI. CONCLUSIONS BFN for tringulr subrrys of three rditing elements hs been studied. Intrinsic fetures of lossless networks limit the 68% 86% 69% 68% 64% 85% 63% 67% Fig. 13. Mesurements of the rdition pttern of the brodside bem (), nd the generl rdition pttern of tilted bem, (b). Mesured (red) nd simulted (blue) sections of the min plne rdition ptterns for brodside (c), nd tilted (d) bems. number of bems generted leding the investigtion to dissiptive network. A novel qusi-orthogonl network providing three orthogonl bems in desired 9Q elevtion ngle nd n extr brodside one hs being proposed. Besides, 7 x 3 network bsed on two complementry of those novel bem-formers hs been described. Prcticl implementtions of both networks hve been pplied to GEODA tringulr subrry cell. Mesurements ensure correct behvior of both systems, proving the effectiveness of the proposed innovtive BFN design. REFERENCES [1] A. orre, J. Gonzlo, M. Pulido, nd R. M. Rodriguez-Osorio, "New genertion ground segment rchitecture for LEO stellites," in Proc. 57th Int. Astronuticl Congr., Vlenci, Spin, Oct. 006, pp [] C. A. Blnis, Modern Antenn Hndbook. New York, NY, USA: Wiley, 008. [3] L. C. Godr, Smrt Antenns, 1st ed. Boc Rton, FL, USA: CRC. [4] M. A. Sls Nter, A. Grci Aguilr, J. Mor Cuev, J. M. Fernández, P. Pdill D L orre, J. Grcí-Gseo rujillo, R. M. Rodriguez-Osorio, M. Sierr-Peréz, L. De Hro Ariet, nd M. S. Cstñer, 'New Antenn Arry Architectures for Stellite Communictions, Advnces in Stellite Communictions," in Advnces in Stellite Communictions, M. Krimi nd Y. Lbrdor, Eds. Mdrid, Spin: Universidd Politechnic de Mdrid.

8 [5] R. Milloux, Phsed Arry Antenn Hndbook. Norwood, MA, USA: Artech House. [6] R. O. Schmidt, "Multiple emitter loction nd signl prmeter estimtion," in Proc. RADC Spectrum Estimtion Workshop, Griffiss Air Force Bse, NY, USA, 1979, pp [7] R. C. Johnson nd H. Jsik, Antenn Engineering Hndbook. New York, NY, USA: McGrw-Hill, [8] [9] [11] J. Grcí-Gseo rujillo, M. Sls Nter, I. Montesinos, M. Aris Cmpo, M. Sierr Pérez, nd R. Mrtinez, "GEODA-GRUA: Adptive multibem conforml ntenn for stellites communictions," presented t the 30th URSI Generl Assembly nd Sci. Symp. Int. Union of Rdio Sci., Istnbul, urkey, Aug J. Grcí-Gseo rujillo, M. Sierr Pérez, A. Novo Grci, nd M. Ver-Iss, "Multibem network design nd mesurement for tringulr rry of three rditing elements," presented t the 5th Eur. Conf. Antenns nd Propgtion, Rome, Itly, Apr [10] B. omsic, J. urtle, nd S. Liu, "A geodesic sphere phsed rry ntenn for stellite control nd communiction," presented t the XXVII Generl Assembly of the Int. Union of Rdio Sci., Mstricht, he Netherlnds, Aug. 00. S. Liu, B. omsic, S. Hwng, nd J. urtle, "he geodesic dome phsed rry ntenn (GDPAA) for stellite opertions support," in Proc. IEEE 18th Int. Conf. Appl. Electromgnetics nd Commun., Dubrovnik, Croti, Apr. 006, p. 1. [1] I. Montesinos, M. Sierr Pérez, J. L. Fernández, R. Mtinez, nd J. L. Ms, "GEODA: Adptive ntenn of multiple plnr rrys for stellite communictions," presented t the Eur. Conf. Antenn nd Propgtion, Berlin, Germny, 009. [13] A. K. Bhttchryy, Phsed Arry Antenns. New York, NY, USA: Wiley. [14] R. H. Roy nd. Kilth, "Esprit-estimtion of signl prmeters vi rottionl invrince techniques," IEEE rns. Acoust., Speech, Signl Process., vol. 37, no. 7, pp , Jul [15] R. Hnsen, Phsed Arry Antenns. Hoboken, NJ, USA: Wiley, [16] J. Butler nd R. Lowe, "Bem-forming mtrix simplifies design of electroniclly scnned ntenns," Electron. Design, vol. 9, pp , Apr [17] J. Blss, "Multidirectionl ntenn - A new pproch to stcked bems," in IRE Int. Convention Record, 1960, pp , Prt 1. [18] W. Rotmn nd R. urner, "Wide-ngle microwve lens for line source pplictions," IEEE rns. Antenns Propg., vol. AP-11, no. 6, pp. [19] 63-63, Jun J. H. Kim, K. D. Jng, W. J. Byun, B. S. Kim, K. S. Kim, M. S. Song, nd W. S. Prk, "Design of novel switched four bem rry ntenn for millimeter wve," in Proc. IEEE Antenns nd Propgtion Soc. Int. Symp., Jun. 9-15, 007, pp L nd S bnds. Jvier Grcí-Gseo rujillo ws born in 1986 in oledo, Spin. He received the M.Sc. degree in telecommuniction engineering from the echnicl University of Mdrid (UPM), Mdrid, Spin, in 009. Since then, he is Ph.D. degree student in the Rdition Group, Signl, Systems nd Rdiocommunictions Deprtment, UPM. His min reserch interest is reconfigurble plnr phsed rry ntenns, focusing on multi-bemforming networks nd trnsmission/reception modules for Alvro Novl Sánchez de oc ws born in Mdrid, Spin, in He received the M.Sc. degree in telecommuniction engineering from the echnicl University of Mdrid (UPM), Mdrid, Spin, in 011. He is currently working towrd the Ph.D. degree in the Rdition Group, UPM, s recipient of Spnish Ministry of Science nd Innovtion Scholrship ( ). His reserch interests include ctive rry ntenn design with electronic steering for stellite communictions. He is prticipting in ntionl nd interntionl investigtion. h *É bem-forming networks. mteril structures with Igncio Montesinos-Ortego ws born in León, Spin, on April 19, He received the B.S., M.S., nd Ph.D. degrees in electricl engineering from echnicl University of Mdrid (UPM), Mdrid, Spin, in 007, 009, nd 01, respectively. From 007 to 009, ws Reserch Associte in the Rdition Group of UPM. From 009 to 011, he becme Reserch Associte t Ando & Hirokw Lbortory t okyo Institute of echnology, okyo, Jpn. His reserching interests re plnr wveguide rrys, smrt ntenn rrys nd José-Mnuel Fernández ws born in Lusnne, Switzerlnd, in He received the Diplome d'ingénieur en Electricité from the Ecole Polytechnique Fedérle de Lusnne (EPFL), Lusnne, Switzerlnd, in 003. He received the M.S. nd Ph.D. degrees in electricl engineering from echnicl University of Mdrid (UPM), Mdrid, Spin, in 003 nd 009, respectively. Since 009, he is Postdoctorl Resercher in the Rdition Group t echnicl University of Mdrid. His current reserch interest is in the field of metemphsis on plnr ntenn pplictions. Mnuel Sierr-Peréz ws born in Zrgoz, Spin, in 195. He received the Mster degree (elecommuniction Engineer) from the echnicl University of Mdrid (UPM), Mdrid, Spin, in 1975 nd the Ph.D. degree in He becme Full Professor t UPM in He hs led lrge number of reserch projects with public orgniztions nd compnies. He is the uthor of severl books nd book chpters nd is reviewer of ppers on reserch projects. His reserch experience nd min interest is in the re of ntenns nd rdiofrequency circuits ssocited with ntenns. In recent yers, his min reserch projects delt with the design of ntenn rrys, either ctive or pssive, nd ssocited circuits.