theory and performance of a space-fed , planar, phased-array antenna \A/ith 849 iris

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theory and performance of a space-fed ,
planar, phased-array antenna \A/ith 849 iris-
loaded rectangular-waveguide elements
and external matching sheet
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theory and performance of a space - fed ,
planar, phased-array antenna \A/ith 849 Iris-
loaded rectangular-waveguide elements
and external matching sheet
BIBLIOTHEEK TU Delft
P 1147 5426
C 270932
theory and performance of a space - fed ,
planar, phased-array antenna with 849 iris-
loaded rectangular-waveguide elements
and external nnatching sheet
proefschrift
ter verkrijging van de graad van doctor in de technische wetenschappen
aan de technische hogeschool delft, op gezag van de rector magnificus
prof. dr ir. f. j. kievits, voor een commissie aangewezen door het
college vandekanen te verdedigen op woensdag 6 juni 1979 te 14.00 uur
door
helmut Johannes van schaik
elektrotechnisch ingenieur
geboren te woerden
r
DIT PROEFSCHRIFT IS GOEDGEKEURD DOOR DE PROMOTOR
PROF.DR.IR. A.T. DE HOOP
EN DE COPROMOTOR
PROF.IR. L. KRUL
L
Aan de nagedachtenis van mijn oudere
Aan Ingvid en Eria
VOORWOORD
Het onderzoek beschreven in dit proefschrift, was een gedeelte
van het werkprogramma van het Physisch Laboratorium TNO te Den
Haag. Aan het bestuur van de Rijksverdedigingsorganisatie, dat mij
toestemming heeft willen verlenen tot het publiceren van de
resultaten van dit onderzoek, zou ik mijn hartelijke dank willen
betuigen. Tevens wil ik mijn dank betuigen aan de vele collega's
op het Physisch Laboratorium, die mij behulpzaam waren bij het
realiseren van dit proefschrift. In het bijzonder wil ik
Mw. Hanny Ernens-Troost bedanken voor de verzorging van het
typewerk.
VI
CONTENTS
SUMMARY A
Chapter 1
INTRODUCTION 1
Chapter 2
DESCRIPTION OF THE COMPLETE ANTENNA SYSTEM 9
2.1 Description of the configuration 9
2.2 Geometry in the domain of the feeding system 11
2.3 Geometry of the matching structure 13
Chapter 3
THE ELECTROMAGNETIC FIELD AND ITS REPRESENTATION IN THE
MATCHING STRUCTURE AND SURROUNDINGS 18
3.1 The electromagnetic field equations and the 18
matching conditions
3.2 The waveguide modes 24
3.3 Representation of the field in the terminal
plane 27
3.4 Grating modes in the radiating domain with
external dielectric matching structure 29
Chapter 4
TRANSFER PROPERTIES OF THE CONFIGURATION 3 5
4.1 Transfer matrix of the matching structure
in s > 0 35
4.2 Matching of the different representations
to the electric aperture field and matrix
formulation of the problem 42
VII
CONTENTS
Chapter 5
FAR-FIELD RADIATION PATTERN
5.1 Illumination function
5.2 Radiation pattern of a finite, planar
array of (2P+1) x (2^+1) elements
Chapter 6
NUMERICAL RESULTS
6 . 1 Introduction
6.2 Numerical aspects of the problem
6.3 Comparison between the results obtained by
different methods
6.4 A parameter study of the influence of an
inductive iris on the performance of a
phased-array antenna
6.5 Influence of an external dielectric sheet in
combination with inductive irises in the
apertures on the antenna performance
6.6 Theoretical radiation patterns
Chapter 7
EXPERIMENTAL RESULTS
7.1 Introduction
7.2 Experimental arrangement
7.3 Phase corrections
7.4 Measured far-field radiation patterns
7.5 Influence of the matching structure on the
transmitted power of the antenna
APPENDIX
A. Mode matching technique according to Lee
B. Determination of the integrals occurring in
matching equations
C. The power balance
VIII
CONTENTS
REFERENCES 141
SAMENVATTING 144
LEVENSBERICHT 149
t A part of this thesis has been published in: IEEE Trans. Antennai
and Propagation, Vol. AP-26, po. 413-420, May 1978.
A part of this thesis has been published as a conference paper
for the International Conference on Radar in: lEE Conference
Publication, No. 155, pp. 437-441, London, October 25-27, 1977.
A part of thesis has been published as a conference paper for
the International Conference on Antennas and Propagation in:
lEE Conference Publication, No. 169, pp. 11-15, London,
November 28-30, 1978.
IX
SUMMARY
In the present thesis we analyse the performance of an iris-
loaded, medium gain, planar, space-fed, phased-array antenna of
rectangular waveguides with an external dielectric sheet. In the
transmitting mode, the antenna is illuminated by a coherent incident
field, originating from a feeding horn whose axis coincides with
the axis of the antenna. At the illumination side of the antenna,
the incident wave is partially reflected and partially transmitted.
The transmitted wave passes through a first array of waveguides,
next through the adjustable phase shifters and then through a
second array of waveguides. Owing to the free-space propagation of
the wave emitted by the feeding horn, we must establish a phase
correction to transform this wave into one with a plane equiphase
surface, parallel to the plane of the antenna. In order to steer
the radiated beam in a prescribed direction, we must further
introduce a certain phase shift between adjacent elements.
Due to coupling effects, a loss in transmitted power occurs,
both at the illumination side and at the radiating side of the
antenna. Because the loss in transmitted power at the illumination
side of the antenna is expected to be sufficiently small, no
compensation of coupling effects is included at this side of the
antenna. At the radiating side of the antenna, however, a considerable
loss in transmitted power can arise under certain conditions and
therefore we introduce as a compensation of coupling effects, a
symmetrical, rectangular iris in each radiating aperture. In
addition, we position a dielectric sheet in front of, and parallel
to, the radiating plane of the antenna.
In this thesis we develop a theory to determine the influence
of this matching structure (iris + dielectric sheet) on the
performance of the antenna. On the basis of this theory, the
parameters of the matching structure are determined such that the
loss in transmitted power due to coupling effects at the radiating
side of the antenna is minimized. Further, we determine the
electromagnetic field in the far-field region of the antenna.
We also present a method to transform the wave emitted by the
feeding horn into one with a plane equiphase surface, parallel to
the plane of the antenna.
X