Development of Integrated Printed Array Antennas Using EBG Substrates

196 Pages·2006·8.77 MB·English

Ph.D. Thesis
Development of Integrated Printed Array
Antennas Using EBG Substrates
Nuria Llombart Juan
Directores: Dr. Andrea Neto (TNO, The Netherlands)
Dr. Vicente E. Boria Esbert (UPV, Spain)
TesisDoctoralrealizadaenelDepartamentodeComuni-
caciones de la Universidad Polit(cid:19)ecnica de Valencia para
la obtencio(cid:19)n del t(cid:19)(cid:16)tulo de Doctor Ingeniero de Teleco-
municacio(cid:19)n
Valencia, Abril 2006

A mis padres

Foreword
This thesis has been done in collaboration between the Polytechnic University of
Valencia in Valencia, Spain, and the Defence, Security and Safety Institute of the
Netherlands Organization for Applied Scienti(cid:12)c Research (TNO) in The Hague, The
Netherlands. The work was guided by Andrea Neto from TNO and Vicente E. Boria
Esbert from the UPV. All the thesis has been hosted by TNO.
The initial period of the thesis has been (cid:12)nanced by the research training network
\Millimetre-wave and Microwave Components Design Framework for Ground and
Space Multimedia Network" (MMCODEF) sponsored within the Fifth Framework
Programme of European Union, under the supervision of Giampiero Gerini.
Afterwards the (cid:12)nancial support comes mainly from two sources. The (cid:12)rst is a
Ph.D. project from the AIO Funds of the Dutch Ministry of Defence, while the
second one is the project \Validated Electromagnetic Modelling of Metal-Dielectric
Photonic Bandgap (PBG) Structures" (No. 17539/03/NL/JA) from the European
Space Agency (ESA). The project o(cid:14)cer in ESA-ESTEC was Peter De Maagt.

Abstract
The main objective of this thesis is to present a strategy to develop innovative an-
tenna architectures, based on Electromagnetic band-gap (EBG) technology, which
can meet fundamental requirements for integrated front-ends like: low cost, low pro-
(cid:12)le,highgainandeaseofintegrationwiththeTransmit/Receivemodules. Important
(cid:12)elds of application are front-ends for Synthetic Aperture Radar (SAR) and 60 GHz
wireless L.A.N.
This thesis introduces the use of Planar Circularly Symmetric (PCS) EBG struc-
tures for reducing the surface waves excited by printed antennas on dense dielectric
substrates. The advantages of PCS-EBGs are the following: they are simple to
manufacture since they do not present vertical via holes or pins, PCS-EBGs do
present the same band gap properties for di(cid:11)erent directions of propagation, and
they can be designed starting from a two-dimensional equivalent geometry with a
one-dimensionalperiodicity. Integratedplanarprintedantennaswithbandwidthsup
to 20% are successfully designed, manufactured and tested.
The design of integrated arrays scanning predominantly in one plane can also sig-
ni(cid:12)cantly bene(cid:12)t from the use of PCS-EBGs. Using this technology, a phased array
that scans up to 40 in one dimension and that is characterized by relatively large
(cid:14)
bandwidth (BW around 15%) is designed, manufactured and measured. The spe-
ci(cid:12)c advantages coming from the use of PCS-EBGs are twofold. On one hand, the
losses associated to surface waves are signi(cid:12)cantly reduced. On the other hand, each
element of the array has a larger e(cid:11)ective area that leads to a higher gain for the
complete array when compared with a standard technology. Additional bene(cid:12)ts are
the low cross-polarization levels, the front to back ratio considering that the antenna
does not include a backing re(cid:13)ector, and the low pro(cid:12)le.
Nowadayspowerfulcommercialtoolsareavailableforthedesignofprintedantennas.
These tools are able to simulate complicated structures, but they do not provide a
physical insight into the problem. EBGstructures, as the metallic-dielectricperiodic
structures, can be seen as periodic arrays embedded in a dielectric environment.
Therefore the analysis techniques are similar to the ones used for phased arrays,
both in(cid:12)nite and (cid:12)nite approaches. In order to analyze the dispersion properties of
EBG structures, the Spectral Green’s Function of the structure has been derived by
integratingtheresponsesofthestructuretobothtypesofplanewaves, homogeneous
and inhomogeneous. During this thesis it is shown that the study of (cid:12)nite EBGs
is an important design tool. Regarding this scope, a Method of Moments based on
entire domain basis functions has been developed.

i
Contents
1 Introduction 1
1.1 EBG State of the Art Before This Work . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 Methodologies for the Analysis of Printed Antennas and EBGs . . . . . . . . . . 3
1.3 Thesis Goal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3.1 Leading Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3.2 Low Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3.3 Dense Dielectrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3.4 Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3.5 Analysis Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.4 Thesis Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Antennas Printed in Dielectric Substrates 9
2.1 Antenna Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2 Surface Waves in Dielectric Substrates . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3 Radiation E(cid:14)ciency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3.1 Method of Moments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3.2 Radiated Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.3.3 Surface Wave Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.4 Substrate Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.4.1 Surface-wave Less Substrate . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.4.2 Ideal EBG. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3 Optimized Method of Moments 31
3.1 Asymptotic Green’s Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.1.1 Sources Between Two In(cid:12)nite Dielectrics. . . . . . . . . . . . . . . . . . . 32
3.1.2 Sources in any Strati(cid:12)cation . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.2 Periodic Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.2.1 Skewed Array Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.3 Single Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.4 Validating Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.4.1 Analysis of Periodic Structures . . . . . . . . . . . . . . . . . . . . . . . . 41
3.4.2 Analysis of Single Structures . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
ii Contents
4 Arrays of In(cid:12)nite Strip Gratings: 2-D-EBG 47
4.1 Periodic Structures Excited by Non Periodic Sources . . . . . . . . . . . . . . . . 47
4.1.1 2-D-EBG Green’s Function: TM Case . . . . . . . . . . . . . . . . . . . . 48
4.1.2 Complex Plane Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.1.3 Dispersion Equation for Monomode Slabs . . . . . . . . . . . . . . . . . . 51
4.1.4 Validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
4.1.5 EBG Design Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
4.2 Finite 2-D-EBG in Presence of the Antenna . . . . . . . . . . . . . . . . . . . . . 58
4.2.1 Radiation E(cid:14)ciency of 2-D-EBGs . . . . . . . . . . . . . . . . . . . . . . 58
4.2.2 Single Mode Field Representation . . . . . . . . . . . . . . . . . . . . . . 60
4.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
5 Entire Domain Basis Functions for the Analysis of Finite Arrays 69
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
5.2 Printed Transmission Line Green’s Functions . . . . . . . . . . . . . . . . . . . . 70
5.2.1 Travelling and Fringe Contributions to the GF . . . . . . . . . . . . . . . 72
5.2.2 Particular Cases: the Slot-line and the Microstrip-line . . . . . . . . . . . 74
5.2.3 Microstrip Transmission Line . . . . . . . . . . . . . . . . . . . . . . . . . 75
5.2.4 Slot Transmission Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
5.3 Entire Domain GF-based Basis Functions . . . . . . . . . . . . . . . . . . . . . . 76
5.3.1 Travelling Wave Basis functions . . . . . . . . . . . . . . . . . . . . . . . . 77
5.3.2 Fringe Basis Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.3.3 Bend Junctions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
5.4 MoM Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
5.4.1 Resonant Microstrip-Coupled Slot . . . . . . . . . . . . . . . . . . . . . . 81
5.4.2 Non Resonant Microstrip-Coupled Leaky-Wave Slot . . . . . . . . . . . . 83
5.4.3 Slot Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
5.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6 Planar Circularly Symmetric EBG Structures 89
6.1 TM Symmetric Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6.1.1 Integral Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6.1.2 Method of Moments Solution . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.1.3 Equivalence Between 2-D-EBG’S and PCS-EBG’S . . . . . . . . . . . . . 93
6.2 Non Symmetric Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
6.2.1 Rectangular EBG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6.2.2 Applicability of the Single Mode Representation: Selection of (cid:26) . . . . . 99
1
6.3 Single Antenna Prototypes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
6.3.1 Surface Wave Coupling Reduction . . . . . . . . . . . . . . . . . . . . . . 101
6.3.2 Radiation Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
6.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
7 PCS-EBG for Printed Arrays 109
7.1 1-D Scanning Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
7.1.1 S Parameters of embedded elements . . . . . . . . . . . . . . . . . . . . . 110
7.1.2 Active Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113