Next Generation Wideband Antenna Arrays for Communications and Radio Astrophysics

107 Pages·2017·45.25 MB·English

Next Generation Wideband Antenna Arrays for
Communications and Radio Astrophysics
CHRISTOS KOLITSIDAS
Doctoral Thesis in Electrical Engineering
School of Electrical Engineering
KTH Royal Institute of Technology
Stockholm, Sweden 2017
TRITA-EE 2017:167 KTH School of Electrical Engineering
ISSN 1653-5146 SE-100 44 Stockholm
ISBN 978-91-7729-612-6 SWEDEN
Akademisk avhandling som med tillstånd av Kungliga Tekniska högskolan framlägges
till offentlig granskning för avläggande av teknologie doktorsexamen mandågen den 11
december 2017 kl. 13:00 i Kollegiesalen, Brinellvägen 8, Kungliga Tekniska högskolan,
Stockholm.
© Christos Kolitsidas, December 2017
Tryck: Universitetsservice US AB
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To my wife Katerina
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Επιστήμη ποιητική ευδαιμονίας
Πλάτων
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Abstract
Wideband, wide-scan antenna arrays are a promising candidate for the future
wirelessnetworksandaswellasanessentialpartofexperimentalradioastrophysics.
Understanding the underline physics of the element performance in the array envi-
ronment is paramount to develop and improve the performance of array systems.
Thefocusofthisthesisistodevelopnovelwidebandantennaarraytechnologiesand
develop new theoretical insights of the fundamental limits of antenna arrays. The
developed methodologies have also been extended to include a radio astrophysics
application for the global 21cm experiment.
Investigating the fundamental antenna array limits and extracting general per-
formance measures can provide a priori estimates for any application of arrays. In
this thesis, a general measure for antenna arrays, the array figure of merit is pro-
posed. Thismeasurecouplesbandwidth,heightfromthegroundplaneandreflection
coefficient in a bounded quantity. An extension of the array figure of merit that is
able to provide matching, bandwidth and directivity/gain limits is also introduced.
The soft Vivaldi array is introduced as a novel wideband, wide-scan angle ar-
ray technology. Periodic structure loading has been utilized to improve the array’s
performance and mold the electromagnetic wave behavior to our benefit. The soft
condition has been utilized in the same manner as the conventional soft-horn an-
tenna at the Vivaldi element. An integrated matching layer in the form of periodic
striploadingisintroduced. AsinglepolarizedsoftVivaldiarrayprototypehasbeen
developed fabricated and measured. The developed finite array has been loaded
withasoftconditionintheperipherytomitigateedgeeffects. Theresultsindicated
improved cross-polarization and side-lobe levels.
A new class of wideband antenna arrays, the Strongly Coupled Asymmetric
Dipole Array (SCADA) was also proposed in this thesis. Exploiting asymmetry in
the array element introduces an additional degree of freedom that improves band-
widthandscanningperformance. Anovelmethodologyforterminatingfinitearrays
is also proposed. The theory and an experimental antenna array is presented with
good agreement between measured and simulated results. An effort to integrate a
vertical wide angle matching layer was also addressed and a prototype array with
this concept is presented.
In the last part of this thesis, a methodology for the detection of the global
cosmological 21cm signal from the Epoch of Reionization (EoR) is developed. The
main sources of errors in this experiment, the foregrounds and the antenna chro-
maticity are evaluated. A new algorithmic methodology for extracting the global
EoR signal is proposed. The method is based on piecewise polynomial fitting and
hassuccessfullybeenappliedandevaluated. Anantennaarraythatisbasedonthe
methodologies described in this thesis has been developed and evaluated with the
proposed algorithm.
Keywords: array figure of merit, fundamental limits, wideband array, wide
scan-angle array, strongly coupled asymmetric dipole array, periodic loading, soft
Vivaldi array, 21cm Cosmology, Epoch of Reionization.
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Sammanfattning
Bredbandigagruppantennermedstorutstyrningsvinkelärenavdelovandekan-
didaterna för nästa generations trådlösa kommunikationsnätverk samt en väsentlig
delavexperimentellradioastrofysik.Attförstådebakomliggandefysikaliskaprinci-
pernahosgruppantennenselementäravgörandeförattkunnautvecklaochförbättra
prestandan hos ett gruppantennsystem. Denna avhandling är fokuserad på att ut-
veckla nya bredbandstekniker samt nya teoretiska insikter om de grundläggande
gränserna för gruppantenner. De här utvecklade metoderna har förutom kommuni-
kationstillämpningarocksåtillämpatspåenradioastrofysiktillämpningidetglobala
21cm experimentet.
Att undersöka de fundamentala gränserna för gruppantenner och att utröna
allmängiltiga mått på deras prestandaegenskaper kan möjliggöra a priori uppskatt-
ningar om gruppantenns tillämpbarhet för dess planerade användning. I den här
avhandlingenföreslåsettallmäntkvalitetsmåttpågruppantenner:gruppantennkva-
liten. Detta mått kopplar samman främst bandbredd, reflektionskoefficienten med
antennenstjockleköverettjordplanet.Enutvidgningavbegreppetgruppantennkva-
liten, presenters också i avhandlingen det kopplar samman bandbredd, matchning
med antennens direktivitet/förstärkningsfaktor.
EnVivaldi-gruppantennmedmjukaytorintroducerashärsomennysortsbred-
bandig gruppantenn med stor utstyrningsvinkel. I antennen har en periodisk be-
lastning inkluderats för att förbättra dess egenskaper, och för att forma antennens
elektromagnetiska utstrålning till vår fördel. Den mjuka ytan på elementet har an-
vändspåettliknandesättsomdetvälkändakorrigeradeVivaldihornetsdesign,och
harintegreratsdirektielementetsdesign.Denhärutveckladeändligagruppantennen
har också en mjuk yta på dess yttre delar för att minska kanteffekternas påverkan
av antennprestandan. Resultaten indikerade både förbättrad korspolarisations och
lägre sidlobsnivåer hos antennen.
Ennyklassavbredbandigagruppantennerharutvecklasidennaavhandling,den
kallasenStarktKoppladAsymmetriskDipol-gruppAntennen-SCADA.Genomatt
utnyttjageometriskasymmetriiantennelementetintroducerasytterligareenfrihets-
gradsommöjliggörförbättradbandbreddochutstyrning.Vidarepresenterashären
ny metod för impedansterminering av ändliga gruppantenner. Både SCADA-teorin
samtdessverifieringiformaavenexperimentellgruppantennpresenterashär.Teori,
simulering och experiment visar god överenskommelse, vilket validerar idéerna. En
prototyp av ett matchande skikt som stöder stor utstyrbarhet har integrerats med
gruppantennprototypen och presenteras i avhandlingen.
Idensistadelenavavhandlingutvecklasocksåenmetodfördetekteringavden
globala kosmologiska 21 cm-signalen från universums rejoniseringsepok - EoR. Hu-
vudkällornaförmätfelidettaexperimentutvärderas,deärantennenskromaticiteten
ochförgrundsstrålningen.Ennyalgoritmbaseradmetodförattextraheradengloba-
laEoR-signalenföreslås.Metodenärbaseradpåanpassningmedmultiplapolynom
och har med framgång tillämpats och utvärderats. En gruppantenn som baseras på
de metoder som beskrivs i avhandling har också föreslagits och dess prestanda har
utvärderats med den föreslagna metoden.
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Nyckelord: Gruppantennkvaliten, fundamentala begränsningar, bredbandiga
antenner, stor utstyrningsvinkel, gruppantenn med starkt kopplad asymmetriska
dipoler, periodisk belastning, Vivaldi-gruppantenn med mjuk yta, 21cm kosmologi,
Rejoniseringsepoken.
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Preface
This thesis is in partial fulfillment for the degree of Doctor of Philosophy at KTH Royal
Institute of Technology, Stockholm, Sweden.
TheworkinthisthesiswascarriedattheDepartmentofElectromagneticEngineering
attheSchoolofElectricalEngineeringatKTHduringSeptember2012tillDecember2017.
Professor Lars Jonsson has been the main advisor and parts of this thesis have been co-
supervised by Associate Professor Oscar Quevedo-Teruel, Dr. Eloy de Lera Acedo at
Cambridge University, Cavendish Lab, UK, Assistant Professor Andrés Alayón Glazunov
at Chalmers and Dr. Patrik Persson from Ericsson Research.
The thesis was supported by VINNOVA Excellence Research Centers Chase and
ChaseOn though the projects Next Generation Antenna Arrays (NGAA, 2016) and Inte-
grated Antennas (ChaseON, 2017).
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Acknowledgements
ThePhDthesisisthelastlegofafiveyearlongjourney. Itisajourneytodiscoverythat
sets off without a clear destination and path, but once it’s revealed, your world is never
the same. Now, that my journey has come to an end, I feel the need to make an attempt
to acknowledge all the people that were alongside me.
Firstandforemost,Iwouldliketothankmymainsupervisor,ProfessorLarsJonsson,
fortakingthechancewithme,hiscontinuesupportduringmyPhDstudies,theinteresting
and stimulating discussions and the opportunity to work in several different research
topics. Also, my co-supervisor, Associate Professor Oscar Quevedo-Teruel for his energy,
continuoussupportandpositivity. Itwasabreezetohaveyouonboard. Myco-supervisor
fromEricsson,Dr. PatrikPerssonfortheinvaluablesuggestionsandhispositivepushfor
asuccessfuloutcomeoftheproject. DuringmylastyearofthePhDstudies, Ivisitedthe
Cavendish Lab of Cambridge University and had the opportunity to work with Dr. Eloy
deLeraAcedo. Dr. deLeraintroducedmetothemagnificentworldofradioastrophysics
and guided me to a different application of antenna arrays. I would like to thank him for
his hospitality in UK, his guidance and our stimulating discussions. Last, but certainly
not least, I would like to thank Assistant Professor Andrés Alayón Glazunov for our
fruitful collaboration, our talks and his continuous support. It was great to have all of
you on board and I learned a lot from each of you.
The CHASE center and VINNOVA are greatly acknowledged for the financial sup-
port of the project. In particular, I would like to acknowledge our partners in the project
"Next Generation Antenna Arrays" Ericsson, RUAG and CHALMERS. Professor Mari-
annaIvashina,AssociateProfessorRobMaaskant,Dr. JohanWettergrenandDr. Anders
Stjernman, who were always there to support the project and see it to a successful out-
come.
IwouldliketothankandacknowledgeDr. LeiWang,whojoinedourdepartmentdur-
ingmylastyear. Ourcollaboration,discussionsandknowledgeexchangewerestimulating
andexciting. Myformersupervisor,firstmentorandcollaborator,ProfessorGeorgeKyr-
iacou, who transfered to me his passion for antennas and microwaves and introduced me
to the field of applied Maxwellian physics.
The enthusiasm and support of Stefan Engström from the Radio HW technology
researchatSystemsandTechnologyfromEricssonisgreatlyacknowledged. Hispositivity
and vision helped me grow and focalize my energy and I am very grateful to him. The
collaboration with Peter Scott from Ericsson was productive and efficient.
MyfriendsandcolleaguesatthedepartmentofElectromagneticEngineering: Sajeesh,
Elena, Per, Mauricio, David, Kun, Jan-Henning, Fatemeh, Peyman, Du Mian, Janne,
Mahsa, Andrei, Shuai, Qingbi, Mrunal, Patrik, MariannaandHenrik. Itisgreattoknow
youall,youhavebeenthecoreofthedepartment. MyfriendsandcolleaguesfromtheEE
School Ilia, Fransisco, Victor, Dimitri and Boules, it is a privilege to know you and I will
always value our times together. My friend and collaborator from afar, Petro. Special
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thanks to Ruslan for the help on proof reading the thesis.
I would also like to thank our head of the department, Professor Rajeev Thottappillil
for his support and guidance. Dr. Nathaniel Taylor is gratefully acknowledged, I was
always learning something new with every interaction that we had. His support with the
Linux server was always prompt and effective. Professor Martin Norgren for the internal
review of the thesis.
Peter Lönn for the technical support. Carin Norberg, Ulrika Pettersson, Brigitt Hög-
bergandEmmyAxénfortheadministration. JesperFreiberg,formanymechanicalparts
needed during my constructions and his engineering input.
The"kids,"Oskar, Oskar, MartinandGustafwhotookachancewithmeduringtheir
bachelor and showed interest for the antenna world. We had a great journey together
and we were the starting point of a new tradition at the ETK department for the APS
student design competition.
My friends in Greece and especially, Vasoula, Panagioti, George and Stavro that even
thoughwearefar,wealwaysfeelclose. Youhavealwaysbeenthereformeandhavebeen
an anchor to my life.
My family, my mother Katerina, my father Gianni and my two sisters Panagiota and
Anastasia, my parents in-law, Mary and Giorgo and my uncle and aunt, Thanasi and
Litsa. Your love, guidance and support has been a pillar.
My wife Katerina, for her infinite love and understanding to all of my late nights. I
love you and you are the one who made all this possible.
Christos Kolitsidas,
Stockholm, 2017