UNIVERSITY
OF TRENTO
DIPARTIMENTO DI INGEGNERIA E SCIENZA DELL’INFORMAZIONE
38123 Po o – T en o (I aly), Via Somma i e 14
h p://www.disi.uni n.i
OPTIMIZED DESIGN OF A MULTI-FUNCTION/MULTI-BAND
ANTENNA FOR AUTOMOTIVE RESCUE SYSTEMS
R. Aza o, F. De Na ale, M. Donelli, A. Massa, and E. Zeni
Janua y 2011
Technical Repo # DISI-11-085
Op imized Design o a Mul i-Func ion/Mul i-Band
An enna o Au omo i e Rescue Sys ems
Renzo Aza o, F ancesco De Na ale, Massimo Donelli, And ea Massa, and Edoa do Zeni
DEPARTMENT OF INFORMATION AND COMMUNICATION TECHNOLOGY
Uni e si y o T en o, Via Somma i e 14, 38050 T en o, ITALY
Tel.: +39 0461 882057, Fax: +39 0461 882093
E-mail: {and ea.massa, ancesco.dena ale}@ing.uni n.i ,
{ enzo.aza o, massimo.donelli, edoa do.zeni}@di .uni n.i ,
Web: h p://www.eledia.ing.uni n.i
Op imized Design o a Mul i-Func ion/Mul i-Band
An enna o Au omo i e Rescue Sys ems
Renzo Aza o, F ancesco De Na ale, Massimo Donelli, And ea Massa, and Edoa do Zeni
Abs ac . The de elopmen o e icien au omo i e acciden managemen sys ems
equi es he design o complex mul i- unc ion an ennas enabling di e en wi eless
se ices (e.g., localiza ion, oice and da a communica ions, eme gency calls, e c...).
S a ing om di e en speci ica ions (elec ical, mechanical, and ae odynamic), he
design o a mul i unc ion an enna mus conside , in addi ion o he usual an enna design
equi emen s, also in e e ence phenomena a ising om he in eg a ion o di e en
classes o an ennas in a compac de ice. In his amewo k, he pape desc ibes a
me hodology based on a s ochas ic mul i-phases op imiza ion app oach o he design o
an in eg a ed mul i- unc ion/mul i-band an enna sys em. Mo eo e , o an exhaus i e
assessmen , he esul s o an expe imen al alida ion pe o med on a p o o ype o he
mul i- unc ion an enna sys em a e shown and discussed.
Key Wo ds: Mul i- unc ion/Mul i-Band An enna, An enna Design, Wi eless
Sys ems, Sys em In eg a ion, Pa icle Swa m Op imize .
2
1. INTRODUCTION
An e icien acciden managemen sys em o au omo i e applica ions is usually
in e aced wi h se e al wi eless communica ion sys ems enabling di e en unc ions,
such as da a exchange wi h a emo e cen e, iming, and localiza ion. Nowadays, hese
unc ions a e o e ed a low cos s by mobile phone ne wo ks o oice and da a
exchange, and by global posi ioning sys em (GPS) o iming and localiza ion.
The e o e, a sys em able o ully exploi he a ailable wi eless unc ionali ies equi es
an an enna sys em ope a ing in di e en equency bands. Mo eo e , because o he
speci ic applica ion in au omo i e en i onmen s, o he issues a ise conce ned wi h he
coexis ence o mo e an ennas in a limi ed a ea (i.e., he co-si e in e e ence phenomena),
he limi ed weigh , and he olume cons ain s.
This pape desc ibes he me hodology adop ed o design he an enna sys em wi hin he
AIDER (Acciden In o ma ion and D i e Eme gency Rescue) p ojec 1. The main
objec i e o AIDER was he de elopmen o an acciden managemen sys em able o
educe he consequences o a oad acciden by allowing e ec i e escue ope a ions. To
accomplish his ask, AIDER ehicles a e equipped wi h a senso sui e and a da a
acquisi ion sys em aimed a moni o ing he p e- and pos -c ash s a us o he ehicle as
well as i s occupan s. The sys em is able o au oma ically send an eme gency call and a
comple e se o in o ma ion (e.g., audio, ideo, and senso da a) abou he acciden o a
emo e con ol cen e. Towa ds his end, a highly su i able communica ion sys em,
based on he in eg a ion o he unc ions o a cellula and a backup sa elli e
communica ion link (GSM/GPRS and COSPAS-SARSAT sys em), is p o ided o he
in o ma ion exchange be ween ehicle and escue cen e . In addi ion, each AIDER
ehicle is equipped wi h a GPS ecei e in o de o p ecisely loca e he posi ion o he
ca .
The design o an an enna o each wi eless subsys em (COSPAS-SARSAT, GPS,
GSM/GPRS) is no c i ical in i sel , he e being a ailable a la ge numbe o comme cial
1 AIDER is an Eu opean p ojec co- unded by he In o ma ion Socie y Technologies P og amme wi hin
he ini ia i es o he 5 h F amewo k P og amme.
3
de ices on he ma ke . Ne e heless, he design o an in eg a ed an enna equi es g ea
ca e o gua an ee all links o mul iple wi eless se ices by a oiding mu ual coupling
e ec s a ising when he adia ing subsys ems ha e o be placed in a single limi ed
olume.
S a ing om he elec ical guidelines o he escue sys em and by aking in o accoun
he geome ical cons ain s a ising om in eg a ion in a single compac olume wi hin
he body o he ca , he an enna design has been ca ied ou h ough a h ee phase
s a egy desc ibed mo e in de ail in he ollowing sec ion (Sec . 2). Such a design
p ocedu e is based on he use o a s anda d ull-wa e simula o (based on a Me hod-o -
Momen code o on a FDTD code) o p edic he elec omagne ic beha io o each
an enna as well as o he in eg a ed sys em.
To assess he e ec i eness and eliabili y o he op imized sys em, some p o o ypes o
he mul i- unc ion an enna ha e been de eloped and es ed. In Sec . 3, he esul s o he
expe imen al alida ion a e epo ed.
2. ANTENNA SYSTEM OPTIMIZED DESIGN
Le us conside he design o an in eg a ed mul i- unc ion an enna ope a ing in di e en
ange o equencies o exploi a ious wi eless se ices, namely SARSAT,
GSM/GPRS, and GPS wi h he ollowing equi emen s:
{}
{
}
{}
max
maxmin
min ,,,,
aa
aa
aa
VSWR VSWR
G G
≤
≤≤
≥
φθφθ
(1)
being he wo king equency and
{
}
GPSGPRSGSMSRSa ,/,
∈
; and VSWR
indica e he gain and he ol age-s anding-wa e- a io, espec i ely. F om a geome ic
poin -o - iew, he an enna sys em is equi ed o belong o a ixed olume de ined as
G
maxmin
maxmin
maxmin
zzz
ayyy
xxx
a
a
a
≤≤
∀≤≤
≤≤
(2)
whe e
{
iden i ies a poin on he ex en o he a- h an enna sub-sys em.
}
aaa zyx ,,
4
To sol e such a p oblem, a h ee-phase p ocess is conside ed. The i s phase, called
“Single-An enna Type Selec ion”, is aimed a de ining he mo e app op ia e class o
an ennas o each wi eless se ice by aking in o accoun physical as well as elec ic
cons ain s. The second phase (i.e., he “Single-An enna Op imiza ion”) deals wi h he
design o each an enna subsys em as a s and alone de ice on a g ound plane. Then,
s a ing om he solu ions de ined a he second s ep, he “In eg a ed-An enna
Op imiza ion” e ines he in eg a ed sys em o de ine he op imal geome ic placemen
o he di e en an ennas sub-sys ems and o sol e in e e ence p oblems. The las wo
phases we e bo h ca ied ou h ough an op imiza ion p ocedu e.
Mo e in de ail:
Single-An enna Type Selec ion
Wi hin an au omo i e amewo k, an enna sys ems a e commonly ins alled on oo o
he ehicle. This can be modeled by conside ing an in ini e g ound plane loca ed a
. Mo eo e , o gua an ee educed weigh , dimensions and ae odynamic
p ope ies o he in eg a ed an enna and o simpli y he in eg a ion phase o he di e en
subsys ems in a single de ice, i could be p o i able o conside only wi e s uc u es. On
he o he hand, he elec ic and physical equi emen s speci ied in (1) and (2) de ine
some cons ain s on he mos sui able classes o an ennas.
0.0
min =z
As a as he COSPAS-SARSAT and he GSM/GPRS sys ems a e conce ned, a
monopole an enna u ns ou o be a good choice. On he o he hand, he GSM/GPRS
sys em ope a es in wo di e en equency bands. The e o e, a dual-band monopole
an enna migh be adop ed by conside ing a LC uning de ice allowing mul i-band
ope a ions.
A mo e demanding ask is ela ed o he selec ion o a p ope an enna subsys em o he
GPS unc ion, since he possibili y o exac ly loca e a ehicle in an a e -c ash s a us is a
c ucial ask o op imizing he escue managemen in e ms o ime and e ec i eness.
In o de o imp o e he GPS ecei e pe o mance, some key poin s should be
conside ed. An enhancemen o he e ec i eness o a GPS ecei e can be ob ained
ei he by educing he e ec s o mul i-pa h phenomena caused by e lec ions, o
5
achie ing a hemisphe ical co e age o ecei e signals om a la ge numbe o sa elli es.
A good solu ion is ep esen ed by a igh -hand pola ized an enna wi h a good c oss
pola iza ion ejec ion a io able o disc imina e be ween di ec and e lec ed signals. A
la ge numbe o comme cial GPS ecei e s employ low-cos /ligh -weigh pa ch
an ennas, since he a ising adia ion pa e ns p esen s a wide lobe and a ci cula
pola iza ion wi h a p ope eed a angemen . Un o una ely, pa ch an ennas a e na ow-
band de ices and he esonan equency a ies depending on he g ound plane size as
well as on he dielec ic loading [1].
On he o he hand, helical and spi al an ennas adia e a ci cula -pola ized ield on a
wide equency band. Mo eo e , such s uc u es a e ela i ely insensi i e o mu ual
coupling phenomena [2] [3] and hey p esen a wide hemisphe ical lobe as well as good
c oss-pola iza ion- ejec ion- a ios [4] [5] [6] [7] [8]. Acco dingly, a conical e sion o
he so-called wo-a m A chimedean spi al an enna is chosen as e e ence s uc u e.
Single-An enna Op imiza ion
Acco ding o he guidelines de ined in he “Single-An enna Type Selec ion” phase, he
o iginal p oblem is ecas in he ollowing one “de ining he physical pa ame e s o
each an enna sub-sys em o i he elec ical equi emen s in each equency band”.
Analy ically, (1) e o mula es as ollows
{}
(
)
{
}
{} ( )
max
maxmin
min
,
,,,,,
SRSSRSSRSSRSSRS
SRSSRS
SRSSRSSRSSRSSRS
VSWRdl VSWR
Gdl G
≤Ψ=
≤≤
≥Φ=
φθφθ
(3)
SRS
l and being he leng h and he wi e-diame e o he COSPAS-SARSAT
monopole, espec i ely;
SRS
d
{}
(
)
{
}
{}
()
max)2()1(
max)2(min)2(max)1(min)1(
min)2()1(
,,,,
,
,,,,,,,,
GSMGSMGSMGSMGSMGSM
GSMGSMGSMGSM
GSMGSMGSMGSMGSMGSM
VSWRCLdll VSWR
GCLdll G
≤Ψ=
≤≤≤≤
≥Φ=
φθφθ
(4)
6
whe e and a e he whole leng h and he diame e o he dual-band monopole,
espec i ely, while indica es he e ical posi ion along he monopole whe e he
uning ci cui is loca ed;
)1(
GSM
lGSM
d
)2(
GSM
l
L
and C being he alues o he lumped componen s o he
uning ci cui ;
{}
(
)
{
}
{}
()
max)2()1()2()1(
maxmin
min)2()1()2()1(
,,,,,
,,,,,,,,,
GPSGPSGPSGPSGPSGPSGPSGPSGPS
GPSGPS
GPSGPSGPSGPSGPSGPSGPSGPSGPS
VSWRdShh VSWR
GdShh G
≤Ψ=
≤≤
≥Φ=
φθφθ
(5)
whe e ( , ) and ( ) deno e he adius and he posi ion o he lowe (1) and
o he uppe (2) spi al u n o he helix, is he dis ance be ween wo adjacen u ns
o he spi al, and i s diame e .
)1(
GPS
)1(
GPS
h)2()2( ,GPSGPS h
GPS
S
GPS
d
Then, o each an enna subsys em he unknown physical pa ame e a e ob ained by
maximizing a sui able cos unc ion de ined as ollows:
()
{} {}
∑∑∑∑ −
=
−
=
−
=
−
=⎪
⎭
⎪
⎬
⎫
⎪
⎩
⎪
⎨
⎧⎥
⎦
⎤
⎢
⎣
⎡ΔΨ−
+
⎪
⎭
⎪
⎬
⎫
⎪
⎩
⎪
⎨
⎧⎥
⎦
⎤
⎢
⎣
⎡−ΔΔΔΦ
=Ω 1
0max
max
1
0
1
0
1
0min
min ,0max
,,
,0max F
ia
aa
F
i
V
T
a
aa
a
aVSWR
iVSWR
G
G i
φθ
γ
(6)
whe e
θ
Δ,
φ
Δ, and a e sampling in e als, Δ
{
}
(
)
a
aa i
γ
φ
θ
Φ=ΔΔ
Δ
Φ
,, ,
{}
(
)
a
aa i
γ
Ψ=ΔΨ , a
γ
being he unknown a ay de ining he physical cha ac e is ics o
he a- h sub-sys em (i.e.,
{
}
SRSSRS
SRS dl ,=
γ
,
{
}
CLdll GSM
GSMGSM
GSM ,,,, )2()1(
=
γ
, and
{
}
GPSGPS
GPSGPSGPSGPS
GPS dShh ,,,,, )2()1()2()1(
=
γ
).
Towa ds his end, a sequence o ial solu ions is gene a ed acco ding o a s ochas ic
mul iple-agen s s a egy based on a pa icle swa m op imize (PSO) [9]. The PSO is a
obus s ochas ic sea ch p ocedu e inspi ed by he social beha io o insec s swa ms
p oposed by Kennedy and Ebe ha in 1995 [10]. Thanks o i s ea u es in explo ing
complex sea ch spaces, PSO has been employed wi h success in se e al p oblems in he
7
Finally, in addi ion o he expe imen al alida ion in a semi-anechoic chambe , some
unc ional es s ha e been ca ied ou . To u he assess he GPS unc ionali ies, he
mul i unc ion an enna has been connec ed o a GPS ecei e and i s beha io has been
compa ed wi h ha o an analogous ecei e equipped wi h a pa ch an enna. When
placed in he same a ea, he ecei e equipped wi h he mul i- unc ion an enna p o o ype
ecei ed one o wo sa elli e signals mo e han he ecei e equipped wi h a pa ch
an enna.
4. CONCLUSIONS
In his pape he design o an in eg a ed mul i- unc ion an enna o an au omo i e escue
managemen sys em has been desc ibed. Due o se e al elec ical and geome ical
cons ain s ixed by he p ojec speci ica ions, he design has been aced by means o a
mul i-phase op imiza ion p ocedu e. The design p ocess as well as he esul ing mul i-
unc ion an enna p o o ype has been alida ed h ough expe imen al and nume ical es s.
The compa ison o nume ical and expe imen al esul s in e ms o gain and VSWR as
well as he e i ica ion o he compliance wi h he p ojec cons ain s, ha e con i med
he e ec i eness o he p oposed design p ocedu e.
Fu u e ac i i ies will be aimed a applying he p oposed app oach o he in eg a ion o
di e en kind o an ennas o a ious wi eless se ices.
ACKNOWLEDGMENTS
This wo k has been pa ially suppo ed by he Cen e o REsea ch And
Telecommunica ion Expe imen a ions o NETwo ked communi ies (CREATE-NET)
and in I aly by he p ojec "WILMA - Wi eless In e ne and Loca ion Managemen
A chi ec u e" - Fondo P oge i 2002, Is i u o T en ino di Cul u a.
14
REFERENCES
[1] N. Pad os, J. I. O igosa, J. Bake , M. F. Iskande , “Compa a i e s udy o high-
pe o mance GPS ecei ing an enna designs,” IEEE T ans. An ennas P opaga .,
ol. 45, pp. 698-706, Ap . 1997.
[2] J. D. K aus, An ennas. New Yo k: McG aw-Hill, 1988
[3] C. A. Balanis, An enna Theo y: Analysis and Design. New Yo k: Wiley, 1996.
[4] D. M. Sazono , Mic owa e ci cui s and an ennas. Moscow: Mi Publishe :
Moscow, 1998.
[5] W. L. Cu is, “Spi al an ennas,” IRE T ans. An ennas P opaga ., ol. 8, pp. 298-
306, May 1960.
[6] J. A. Kaise , “The a chimedean wo-wi e spi al an ennas,” IRE T ans. An ennas
P opaga ., ol. 8, pp. 312-323, May 1960.
[7] E. Gschwend ne and W. Wiesbeck, “Low-cos spi al an enna wi h dual-mode
adia ion pa e n o in eg a ed adio se ices,” P oc. Millenium Con . An ennas
P opaga . (AP2000), Da os, Swi ze land, Ap il, 9-14, 2000.
[8] Y. Zhang and H. T. Hui, “A p in ed hemisphe ical helical an enna o GPS
ecei e ,” IEEE Mic owa e Wi eless Componen s Le ., ol. 15, pp. 10-12, Jan.
2005.
[9] A. Massa and M. Donelli, “A compu a ional app oach based on a pa icle swa m
op imize o mic owa e imaging o wo-dimensional dielec ic sca e e s,” IEEE
T ans. Mic owa e Theo y Tech., in p ess.
[10] J. Kennedy, R. C. Ebe ha , and Y. Shi, Swa m In elligence. San F ancisco:
Mo gan Kau mann Publishie s, 2001.
[11] J. R. Robinson and Y. Rahma -Samii, “Pa icle swa m op imiza ion in
elec omagne ics,” IEEE T ans. An ennas P opaga ., ol. 52, pp. 771-778, Ma .
2004.
15
[12] Y. Rahma -Samii, “F on ie s in e olu iona y op imiza ion echniques applied o
an enna designs: gene ic algo i hms and pa icle swa m op imiza ion,” in P oc.
13 h In . Symp. An ennas (JINA 2004), Nice, F ance, 8-10 No . 2004.
[13] D. W. Bo inge and Douglas H. We ne , “Pa icle swa m op imiza ion e sus
gene ic algo i hms o phased a ay syn hesis,” IEEE T ans. An ennas P opaga .,
ol. 52, pp. 771-779, Ma . 2004.
[14] M. Donelli e al., “An inno a i e compu a ional app oach based on a pa icle
swa m s a egy o adap i e pahsed-a ays con ol,” submi ed o IEEE T ans.
An ennas P opaga .
[15] M.M. Weine , S. P. C uze, C. Li and W. J. Wilson, Monopole elemen s on
ci cula g ound planes, A ech House, 1987.
[16] G. J. Bu ke and A. J. Poggio, Nume ical Elec omagne ics Code (NEC) - Me hod
o Momen s. Law ence Li e mo e Na . Lab., Li e mo e, CA, Tech. Rep. UCID-
18834, 1981.
[17] D. M. Sulli an, Elec omagne ic Simula ion using he FDTD Me hod. IEEE P ess
Se ies on RF and Mic owa e Technology, New Yo k, 2000.
16
FIGURE CAPTIONS
Figu e 1. Geome y o he mul i- unc ion an enna: (a) side iew and (b) op iew.
Figu e 2. Beha io o he cos unc ion (7) e sus he i e a ion numbe .
Figu e 3. Pho og aph o he p o o ype o he mul i- unc ion an enna.
Figu e 4. Mul i- unc ion an enna esul s o COSPAS-SARSAT band: (a) measu ed
and simula ed gain o he s and alone monopole along a e ical plane, (b)
measu ed and simula ed gain o he in eg a ed mul i unc ion an enna along a
e ical plane, (c) measu ed and simula ed VSWR o he s and alone
op imized monopole, (d) measu ed and simula ed VSWR o he op imized
in eg a ed mul i unc ion an enna.
Figu e 5. Mul i- unc ion an enna esul s o GSM/GPRS lowe band: (a) measu ed
and simula ed gain o he s and alone double-band monopole along a
e ical plane, (b) measu ed and simula ed gain o he in eg a ed
mul i unc ion an enna along he “wo s ” e ical plane ( ), (c)
measu ed and simula ed VSWR o he s and alone double-band monopole,
(d) measu ed and simula ed VSWR o he in eg a ed mul i unc ion an enna.
o
162=
φ
Figu e 6. Mul i- unc ion an enna esul s o GSM/GPRS uppe band: (a) measu ed
and simula ed gain o he s and alone double-band monopole along a
e ical plane, (b) measu ed and simula ed gain o he in eg a ed
mul i unc ion an enna along he “wo s ” e ical plane ( ), (c)
measu ed and simula ed VSWR o he s and alone double-band monopole,
(d) measu ed and simula ed VSWR o he op imized in eg a ed
mul i unc ion an enna.
o
150=
φ
Figu e 7. Mul i- unc ion an enna esul s o GPS: (a) measu ed and simula ed gain o
he s and alone conical spi al an enna a , (b) measu ed and simula ed
gain o he in eg a ed mul i unc ion an enna a , (c) measu ed and
simula ed gain o he s and alone conical spi al an enna a , (d)
measu ed and simula ed gain o he in eg a ed mul i unc ion an enna a
.
o
0=
φ
o
0=
φ
o
90=
φ
o
90=
φ
Figu e 8. De ails o he mul i- unc ion an enna p o o ype.
17
Figu e 9. Mul i- unc ion an enna esul s o GPS: (a) measu ed and simula ed VSWR
o he s and-alone conical spi al an enna, (b) measu ed and simula ed
VSWR o he in eg a ed mul i unc ion an enna.
Figu e 10. Mul i- unc ion an enna: measu ed gain in wo o hogonal e ical planes
(, ) o he GPS band wi h a linea pola ized an enna.
o
0=
φ
o
90=
φ
18
TABLE CAPTIONS
Table I. Mul i- unc ion an enna p ojec speci ica ions.
Table II. Geome ic cha ac e is ics o he mul i- unc ion an enna p o o ype.
19
MULTI-FUNCTION ANTENNA SPECIFICATIONS
WIRELESS
LINK FREQ.
[MHz] POLARIZATION GAIN VSWR
( ela ed o 50 Ω)
COSPAS -
SARSAT 406.015 – 406.035 Linea ( e ical) dBi0.3− min
(°
−
≤
≤
°
−
3085
θ
, °
≤
≤
°8530
θ
) 1.5 max
880 – 960 Linea ( e ical)
dBi0.5− min a °
±
=
5.88
θ
dBi0.2− min on a e age
(°
−
≤
≤
°
−
7090
θ
, °
≤
≤
°9070
θ
)
1.5 max a
2
max)1(min)1( GSMGSM −
1.5 max in he 30% o he
equency band
GSM/GPRS
1710 - 1990 Linea ( e ical)
dBi0.5− min a °
±
=
5.88
θ
dBi0.2− min on a e age
(°
−
≤
≤
°
−
7090
θ
, °
≤
≤
°9070
θ
)
1.5 max a
2
max)2(min)2( GSMGSM −
1.5 max in he 30% o he
equency band
GPS 1574.4 – 1576.4 RHCP
dBi0.3 min a °
=
0
θ
dBi0.4− min a °
±
=
70
θ
(wi h a p eampli ica ion o )
dB28
2.0 max
Table 1 – R.Aza o e al., “Op imized Design o a mul i- unc ion/mul i-band an enna ...”
20
MULTI-FUNCTION ANTENNA GEOMETRICAL DIMENSIONS
Max X [mm] Max Y [mm] Max Z [mm]
COSPAS – SARSAT
subsys em 0.5
(wi e adius) 0.5
(wi e adius) 175
(monopole leng h)
GSM/GPRS
subsys em 0.5
(wi e adius) 0.5
(wi e adius) 53
(monopole leng h)
GPS
subsys em
46
(max x o he lowe spi al
u n)
40
(max y o he lowe
spi al u n)
65
(heigh o he op o he
spi al)
MULTI-FUNCTION
ANTENNA 46
(X o GPS subsys .) 40
(Y o GPS subsys .) 175
(Z o SARSAT monopole)
Table 2 – R.Aza o e al., “Op imized Design o a mul i- unc ion/mul i-band an enna ...”
21
(a)
(b)
Fig. 1 – R.Aza o e al., “Op imized Design o a mul i- unc ion/mul i-band an enna ...”
22
0.001
0.01
0.1
1
10
0 50 100 150 200 250 300
W
k
I e a ion numbe , k
Fig. 2 – R.Aza o e al., “Op imized Design o a mul i- unc ion/mul i-band an enna ...”
23
(a)
(b)
Fig. 9 – R.Aza o e al., “Op imized Design o a mul i- unc ion/mul i-band an enna ...”
30
Fig. 10 – R.Aza o e al., “Op imized Design o a mul i- unc ion/mul i-band an enna ...”
31
