Source Localization with Distributal Electromagnetic Component Sellsor Array
coilceut of ~ector-sensorarralvronssiug tvhere the complete
electromagnetic iuforniation of the signnl is inenrural a d
I.lye pmpose an n p p m c h to achieve high-perfoimance /mal- pmd. The>-apply the Poj-iting relatiomhip I r t r e e n
i x t z o n 0.f mdtaple sozmes using n. small aperture anrry o.f
t l r electric and niaguetic nrasnrenrats to enable estimasptially-dzstributcri electric and magnetic conipnent sen- tion of tlr DOA of multiple sigial s o u m s using a single
sors. The n p p m c h Zr; based on exploiting o.f nil nunilable wxtol-siixr. Directioirfinding with a vector s i m r (Sir
electmiiingnetic in,foniirdiorz along uZt/i the time rlelny irz- perC.&RT antema mrav) \vas demoustratecl in [7]. Since it
fonimtion. LXng siiiiulnted dnta. %:edemonstmte thnt this clw6 !lot rely on qxtial diversity, a DOA estimator wing
n p p m c h outpe7:fomis both rc single uertm-sensov m d scolnra *ingle vector s e n a r shonld exhibit consistent performaim
sensor nrmys in nccz~incyo.f di,tio,i-o.f-al7-i~,r'l
es- over its operating frequencj- bawl ancl sllould easil2- xnrk
\Tit11 wide-band signals[l]. \ \ h e n operating as an arraj- of
vector ,wnsors. the electromagnetic arid tinis-delay measureiwnts can I
x siinoltaimiisly urecl to estimate the D 0 . k
1 Introduction
This allows the use of smaller aperturearrays whilc mainThe problem of estimating electminagiietic wave parameters taiuiilg gml performauce over a wide frequency bandtridth.
wing seiimr arrays has attracted significant attention over Howei-er?emplTiig m i array of vector scnsors may be erl a r s nuiiilrr of receivers is necessary. For
iocent years and lead to the dei:elopii=nt a numkr of high pensive I-wle
resolution algorithms, such as LIUSIC. ESPRIT and \\9F. example. a %\:&or snmrs array \vi11 require an I%chamiel
These algoritlims have f o c u , , on direction-of-arrival esti- receiL-er.
This paper propo%s a simple and ellective alternative
mation i n sucli arcas as n~iidcsscoinmimications and radar.
DOR estimation perforinaiice IL-ith small
hlmt existing arra?-procesiug niethods rel5- on tlle spaapertuuparraj-s.
appiloach u=s an arm)- of qmtially c l i s
tial diversit? of tllc mnsor arraj- to estimate the DOA. A
dranback of this approach is that the performance accuracy tributal scalar ntagmtic ancl electric sensors. \Ve .shall call
the ~ ~ p o p array
o ~ l as distributed electmniagiletic c o i n p
b i u e s highly clepenclent GU the size ofthe arra:-'s eierfrzuent array (DEhlCA). I t is assumed that the array of .scalar
cal apeitrur. In many applications: tlw arra? is exlxctcd to
r s in aggegate. nieasure
q x r a t e over a wide frequency range. To avoid ambipitics maguetic a d electric m ~ ~ shouldl
in the array nmnifold: t.lle pliysical size of such h l d b a l K ~ at lead all the 3D electric and mapietic coinimnents of the
array is constrailled Ip the highest operating fkquenc?. ancl electroinagnet.ic maw. The p m l d DEIICA ill aiford tho
the nundxr of snsors. Poorer performaiioe at lower freclueir follox\-ingthree advaitages: Firstly, the fnll electric and magcies rvill E s d t due to their larger wavelengths: especiallj- netic field components measure bj. the maguetic awl electric
mwmrs: tlwrehy ellectuating derivation of the murocs' diroo
when small ~iumberof n?cciver chanmls is available. The
information. s e c O ~ d l ytheir
s p t i a l distribution will
castl?- approacl~to alleviate t.liis problem is t o aim for larger
eA%r.actiou of 'additional m i m s ' diredional informa..unmulhi,vwion3" array ,wnrtry 13)- increasing the n m d x r
way of t l r clilferential-delay nwxmucmelts. Finally.
of receiver chmnmls. Anotlier va:- to overcunie this problem tiou
structure v i l l significantly m u o n i i e the number
is to use multiple sets of senmr arrays where each set is OF
timized to operate ol-er a smaller Ibadn.iclth. This nlay not of imivers i i d c d to simultaneously utilize the timodel%?IE feasible in while- or fast-denloviuent. sensor mrav
. a i d - aid conzplete electromagnetic information for DOA estimaczztions. Hence: there is a netd to develop DO,\ estimation tion'
methods that c m a small-aperture array that nchieve ,
. _
. I
performance ovev a wide operating f r q u c n q .
2 Measurement Model
The DO.& estinmtor's performance cau lx improvecl by
usiu,v Imlarhatiowsensitii~cmnsor am?- to cxploit thc p A d o p t i ~ qthe conv-ntions ill [l]. tlw nlcasu~otnc~lt
model of
Iarization diversit)- of the signals 13-: estimating their signal tlle vector setlmr is 6ir.en by
polarization parameters aloiig a i t h their DOA [2] [3] [4]. In
4 4
a reccnt development. Xehorai and Paldi [I] introduml the
vctws(t) CH(t) ! ( I )
Y H ( t ) = h:;)
C.hI.S. ,See i > iritb DSO National Lahoratories. 20 Scieuce Park
Drive. Singalare 118230. Tel: 065-GS712.123. Fax: 06iFCrS72.135G. \'here
A. Kielarai is n-itb the LIiUiwrsity of Illirois. Cllieago. L!SA. Tel:
Fax:(112)111-002L Etrail: ,,cIurniOece.aic.edu.
0-7803-7946-2/03/$17.00 02003 E E E
] [
is the unit direction vector from s e m r to source and t+, 3 Cramer -0
are the 3. y and 3 mnipoimds. The matrices V .
\Ve U= the CramerRao bimd (CRB) to examine the perQ and vector w are giwn by
formance gain achievable b?. ow approach. CJdng the nota- sin81 -cos& sin&
tions, statistical amnnptions and results in [I] [SI,the CRB
(3) is givenby
where 01; 62. 83 a d 04 are the azimuth, elevation, e l l i p ' s
where P = E (s(t)s"(t))? U = P(A"AP +
orientation a d ecentricit3- angle.
Extending from (1) a d aswming that the signal sources u21)-'AHAP. Il = I - A(AnA)-'A",
D =
are nnrmwbnnd, me can write the measurement model of [By), .D:~I.. D ~. .JD ~ I ]D
, ~ X-I a;;$'~ and 0 =
the distributed component sensor array in a multiple source
em4romnent as [SI
.. .ddIT] and where o2 is the noise power and N
is the nnmher of independent snapshots. In order to c i r
( 5 ) cnnivent the intrinsic singnlaritiesdue to the reference-dinate 3-stem: the mean square augnlar error (LIME) was
propozed in [I] and is given by
= [/??I, Or), 6r'.
deudesthe directiod and 4
Numerical Example
polarization parameters of the kih sounr si,+al. r(B1.02)
is a diapnal matrix dnse n"diapnal entrj- is given l
q B y nsing a numerical example, we shall demonstrate the
[r(B1,8&, = n , ( H 1 . 8 z ) e j W ~ r "xhere
r, is the differential w a t e r efticaq of the distribnted electromagnetic m m p
delaj- of the signal source I&etrvem the nih m n p u e n t and nent s n s o r arra5- (DEhICA) prooessing when it is compared
the phase center and a,(&,&) is the RsponJe of the nth with salar-arraj- processing that relies on an elgtric-only,
mmponent slly3r; uC is the carrier frequenq and R is a diverslj- polarized and -polarized
antenna array. Since
selection matrix elenieuts of 1 and 0. For example, when the motivation of this development is the design of a smallo r t b p n d triads of mapettic ancl electric seaylrs alp nsed. aperture seusor array: we shall make the comparison b d
R = 16. If an additional x electriccomponent sefwor is 4. on the principle of %qndaperture, equal number of channels". We assnine a six-channel receiver and use a six element
the sslection matrix becomes
uniform circular arraj- in this analpis. This will allow the
comprisou betweeu the performance of a vectocsensor as
o= 1 0 0 0 0 0
well as a six element diversely and cs-polarized array with
the p r o p a d DEhICX. The diversel~--polarizedarrq- nsed in
From (5), o k r v e that the electromagwtic sources dire0
this stndy is an array of x ! y and =-electric component sentional information are all e m l d d e d in
sors. The difference between the diversely-polarized and the
p r o p a d sensor array is that the former uses only electric
component sensors while the latter usss hoth electric and
magnetic component sensors to form a six-element sen.mr
This allorvs the dillerrdial dela)- masureiwnts resulting array with a &-channel receimr. The three sensor arrays
from divem placemnt of the component senmrs and elare depicted in Figiue 1. Note that the interelement spa0
tromagnetic field measurements to be jointlj- exploited in ing is fixed at A,,
= A.
where c is the specd of light
2f"estimating the source parameters. Given both the complete a i d fmax is the maximum operating frequency.
electromagnetic and spatial information, g o d pxamcter e s
An example of the DOA estimation performance as a
timation with a smaller apertiue array can be e e e d over function of freqwgc?. is shown in Figure 2. We considered
a wide frequenq range. It sfices to point out that the two nnmrrelated sources with e(')= [lo:10",45°.0Q]Tand
distributed-mqmuent fellrsors array mcdel in (5) general- e(?),=
[5.. 9". -45", -5"IT. The signal-tenoiue ratio is fixed
izes the vectorsensor array [SI.
at IOrlB. Therein the intereleluent spacing of the uniform
We can express ( 5 ) compxtly in matrix form as
O k r v e from the fignre that
circular array is f
the distributed EM sensor array has consistent performance
y ( t ) =As@) n(t)
(7) over a a i d e operating bandwidth. In addition, it achieved
four orders of magnitude of gain in aocoraq of DOA estimaurhelpA = a ( O ( ' ) ) . .a(6cdJ)]and s ( t )= [SI( t )...sd(t)IT. tion over the x electric arraj-and one order of ma,pitiide over
Figure 1: Array C k m e t l ) - of Distributed Eh1 Cwulnneot Seneor
x-electrie (mpolaiized) array and electric-only cliveiwly
lmlarired array. E,(H,). E, ( H y ) a i d E,(H:) ale the electiic Figlire 2: c;RB ~ r sF ~ e q ~ ~ e e e+:
y . DEhlC.4. o : Dix-ersely ID
(eiagnet.ic) eonqmncnt BCIIY)IS.
hrized dipole array. -: Vector leu~y)r.
Scalar array of "
diiertional S ~ J O I S . x : Scalar srmy of x-electric sensor (dipole).
the electric-only. diversel>--polarizcdlarra>- at
= 0.3.
This result clearly denmnstrates the gain obtainable fmin
tlie full exploitation of the spatial ancl ele3romagiIetic information alforclecl k DEhICA.
Figwc 3 plots the DOA estimation pcrforniaixr as a f i n r
tion of tlie azimuthal angle of sparation Ixtwecn i i m r r c
lated two ~ l u p c e shn-ing IOrIB SKR. The uorinalizecl o p r atiiig frquencx is 6xed at
= 0.3. The graph shows
that. the propml DELICA kzonstrates significant performance gain especiallj~for cla?el?;spacecl SOIII'C~S. This feature is p.u.ticnlarl: useful ill applications wit Ii short integration time or at IOK signal-tc-noise ratio.
Concluding Renlarks
\Ve have presentecl a new approach for the localization
of electioinagnetic soiiires thmngh the joint exploitat.ion
of spatid diversit)- and eledromaggaetic information using
electric ancl magnetic coinpone+ ,en-
mrs. Perforinancc aiial:-.;is via numerical examples illas
t r a t d the potential gaiii of the piolmscd. approach over tlie
=:alar and diverse?\- polarized arraj. The analpis indicatd
that the didribated conipooeut Eh1 mum array shoeld allow tlie we of sniall arraj- alm-tiires diile maintaining cl++
sirecl resolution and performance accnracy over a tvicle operatiiig bandaidth.
Figure 3: CRB v s A n p l a r Separation
Ekctmluagnctic Source Localization," IEEE Tram. on S i a l
Pmeessiu~,VoI.42, N o 2 pp.376398, Feb. 1994. (a shorter
vemion of this payer has also appeared in Pme 25th Aailomar
G n f . S i a b Syst. Gmput.: Nov. 1991, pp. 566572)
[Z] E.R. Ferrara Jr. and T.M. Parks, "Direction fiuding with an
array of anteaoa having dive= polarization". IEEE Trans.
Antennas Pmpagat., vol. AP-31, pp.231-236. Mar. 1983.
[3] R. Schmidt. '.A Sigual Subspace Appmach to Multiple Emitter Location and Spectral Estimation; '' Pb.D. dkisertation,
Stanford Unk-eersity, C.A., Nov. 1981.
[4] 1. Ziskind and hl.\Vax: "hlaxhnum Likelihood Localization of
Diverraly Polarized Sources by Simulated healing;.'; IEEE
Trans. A u h n a s and Pmpagatiou, Vol. 38, pp. 1111-1114,
July 1990.
1.51 J. Li. "Direction and Pohrization Estimation Using Arm!-s
with Small Loopi and Short Dipoles: IEEE Tram. Antemar
and Propagation, Vol. 11,No. 3. pp. 379487. hlareh 1993.
[S] C.M.S. % and A. Nehorai. "Distributed Electmniagudie
Component Susor ArraJ-". 7th Annual Adaptive S a w r AF
ray Pioeer;sing Worksbop, M a d 1999. Full version in pmpa
[7] G.F. Hatke, "Perfominnee Analysis of the SuperCAIlT Autcnna Array". Project Peport AST--22: Lhmlu Laboratory,
hlassachcsetts Institute of techno lo^, 23 Mareh 1992.
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF