Digital Beamforming Focal Plane Arrays for Radio Astronomy and Space-Borne Passive Remote ...

294 Pages·2017·21.46 MB·English

Thesis for the Degree of Doctor of Philosophy
Digital Beamforming Focal Plane Arrays
for Radio Astronomy and Space-Borne
Passive Remote Sensing
Oleg Iupikov
Department of Electrical Engineering
Chalmers University of Technology
G(cid:246)teborg, Sweden 2017
Digital Beamforming Focal Plane Arrays for Radio Astronomy and Space-
Borne Passive Remote Sensing
Oleg Iupikov
ISBN 978-91-7597-579-5
' Oleg Iupikov, 2017.
Doktorsavhandlingar vid Chalmers tekniska h(cid:246)gskola
Ny serie nr 4260
ISSN 0346-718X
Department of Electrical Engineering
Antenna group
Chalmers University of Technology
SE(cid:21)412 96 G(cid:246)teborg
Sweden
Telephone: +46 (0)31 (cid:21) 772 1000
Email: [email protected]
Typeset by the author using LATEX.
Chalmers Reproservice
G(cid:246)teborg, Sweden 2017
To my family
(cid:16)Look deep into nature, and then you will understand everything better(cid:17)
-Albert Einstein

Abstract
Dense Phased Array Feeds (PAFs) for re(cid:29)ector antennas have numerous advantages
over traditional cluster feeds of horns in a one-horn-per-beam con(cid:28)guration, espe-
cially in RF-imaging applications which require multiple simultaneously formed and
closely overlapping beams. However, the accurate analysis and design of such PAF
systemsrepresentsachallengingproblem, bothfromanEM-modelingandbeamform-
ing optimization point of view. The current work addresses some of these challenges
and consists of two main parts.
In the (cid:28)rst part the mutual interaction e(cid:27)ects that exist between a PAF consisting
of many densely packed antenna elements and an electrically large re(cid:29)ector antenna
are investigated. For that purpose the iterative CBFM-PO method has been devel-
oped. This method not only allows one to tackle this problem in a time-e(cid:30)cient and
accurate manner, but also provides physical insight into the feed-re(cid:29)ector coupling
mechanism and allows to quantify its e(cid:27)ect on the antenna impedance and radiation
characteristics. Numerous numerical examples of large re(cid:29)ector antennas with var-
ious representative feeds (e.g. a single dipole feed and complex PAFs of hundreds
of elements) are also presented and some of them are validated experimentally. In
order to analyze electrically large feeds e(cid:30)ciently, a domain-decomposition approach
to Krylov subspace iteration, where macro basis functions (or characteristic basis
functions) on each subdomain are naturally constructed from the di(cid:27)erent segments
of the generating vectors, is also proposed.
The second part of the thesis is devoted to the optimization of PAF beamformers
and covers two application examples: (i) microwave satellite radiometers for accurate
ocean surveillance; and (ii) radio telescopes for wide (cid:28)eld-of-view sky surveys. Based
on the initial requirements for future antenna systems, which are currently being
formulated for these applications, we propose various (cid:28)gures-of-merits and describe
the corresponding optimal beamforming algorithms that have been developed. Stud-
ies into these numerical examples demonstrate how optimal beamforming strategies
can help to greatly improve the antenna system characteristics (e.g. beam e(cid:30)ciency,
side-lobe level and sensitivity in the presence of the noise) as well as to reduce the
complexity of the beam calibration models and overall phased array feed design.
Keywords: phased array feeds, re(cid:29)ector antenna feeds, beamforming, feed-re(cid:29)ector
interaction, radio telescopes, spaceborne radiometers.
i
ii
Preface
This thesis is in partial ful(cid:28)llment for the degree of PhD of Engineering at Chalmers
University of Technology.
The work that has resulted in this thesis was carried out between December 2011
andMarch2017andhasbeenperformedwithintheAntennagroupattheDepartment
of Electrical Engineering, Chalmers. Professor Marianna Ivashina has been both the
examiner and main supervisor, and Associate Professor Rob Maaskant has been the
co-supervisor.
Theworkhasbeensupportedbyaprojectgrant(cid:16)SystemModeleringochOptimer-
ing av Gruppantenner f(cid:246)r Digital Lobformning(cid:17) from the Swedish Research Council
(VR), Swedish National Space Board (SNSB) project grant 202-15 (cid:16)Antenna-Array
Digital-Beamforming and Calibration Methods for the Next Generation Multi-Beam
Space-borne Radiometers for Ocean Observation(cid:17) within the framework of the SNSB
2015-R open call for Space and Earth Observation Research, and a grant (cid:16)Study on
Advanced Multiple-Beam Radiometers(cid:17) (contract 4000107369-12-NL-MH) from the
European Space Agency (ESA).
iii
iv
Acknowledgments
First and foremost, I wish to thank my supervisor Prof. Marianna Ivashina for the
opportunity to work on challenging and relevant research topics, and for her contin-
uous guidance and encouragement during these years. I thank her for her patience
and signi(cid:28)cant amount of time she spent in discussing the challenging phased-array
feed problems, reviewing my research papers and technical reports. I am very thank-
ful Prof. Ivashina for teaching me to be an independent researcher by giving me
a chance to be creative in my work. I would also like to thank my co-supervisor
Assoc. Prof. Rob Maaskant for numerous fruitful discussions related to my work,
and for the in(cid:28)nite support in such complicated topics as numerical methods for
electromagnetic modeling, electromagnetic theory, and other technical topics I could
have a question on. All in all, it had been my honor to have worked with both of You.
You are as much as mentors to me as are friends. I would like to thank Prof. Per-
Simon Kildal for welcoming me to the Antenna group. Also, thanks to all of you I
have met my beloved Esperanza :)
ThankstomycolleaguesattheOnsalaSpaceObservatory,especiallytoProf.John
Conway and Dr. Miroslav Panteleev, for providing me with interesting depart-
ment service tasks related to the Square Kilometer Array (SKA) project, which was
also bene(cid:28)cial for my PhD project as I could improve large parts of my Matlab code.
I would also like to thank Drs. Kees van ’t Klooster and Benedetta Fiorelli
from ESA, Drs. Knud Pontoppidan, Per Heighwood Nielsen and Cecilia Cap-
pellin from TICRA, Prof. Niels Skou from Technical University of Denmark for the
interesting and fruitful collaboration on new satellite radiometers, and Dr. Andre
Young from Stellenbosch University for common work on calibration techniques for
radio telescopes. I thank Prof. Christophe Craeye for inviting me to UniversitØ
Catholique de Louvain and for interesting collaboration which had led to our joint
journal publication on numerical methods.
I would like to acknowledge Dr. Wim van Cappellen from ASTRON, The
Netherlands,forprovidinguswithmeasurementsoftheVivaldiantennaPAF(APER-
TIF), that were made at the Westerbork Synthesis Radio Telescope. These measure-
ment results have been very bene(cid:28)cial for validating my numerical models.
My special thanks go to all the former and current colleagues of the Electrical
EngineeringDepartmentforcreatinganiceandenjoyableworkingenvironment.We’ve
had a lot of fun and enjoyable moments both at work and afterwork time.
v
Acknowledgments
Finally,Iwouldliketothankthefacultyopponent,Prof.Bart Smolders,andthe
committeemembers, Prof.Joakim Johansson, Prof.Dirk de Villiers, Dr.Mauro
Ettorre, andDr.Miroslav Pantaleev, forthetime invested inreviewingmy thesis.
This has been a great help in improving the quality and readability of this thesis.
And of course, my most sincere gratitude to my parents, sister and my own family
(cid:21) Esperanza, Marc and Tania (cid:21) for granting me a new sense of life and accompa-
nying me in this scienti(cid:28)c journey.
Oleg
vi