Forum for Electromagnetic Research Methods and Application Technologies (FERMAT)

Transcription

1 Forum for Electromagnetic Research Methods and Application Technologies (FERMAT) Some Reflector and Feed Antenna Technologies that Made a Difference: Fundamentals and examples from radio telescopes, satellite communications and radio links Presentation given as Distinguished Lecturer of IEEE APS Society. There exist a corresponding 3 page text in: P.-S. Kildal, Some Reflector and Feed Antenna Inventions that Made a Difference, Africon 2013, Mauritius Per-Simon Kildal Distinguished lecturer of IEEE Antennas and Propagation Society

2 Abstract The presentation reviews some inventions within reflector antennas and feeds that represented a large step forward when they were introduced, in terms of both performance and industrial or scientific usefulness. The fundamental design principles as well as the actual solutions will be overviewed in a simple manner. The overview covers dipole-disk with ring for ship Earth stations, corrugated horns, hat-fed antennas for radio links, and wideband log-periodic eleven feed for SKA and VLBI 2010 radio telescopes. The inventions can in all cases be associated with simple fundamental EM principles, and an improvement of a fundamental subefficiency. Keywords: Reflectors, feeds, wire grid, PEC/PMC strip grid.

3 About Per-Simon Kildal Per-Simon Kildal (IEEE M 82-SM 84-F 95) has MSEE and PhD from The Norwegian Institute of Technology in Tronheim, Norway. Since 1989 he has been Professor at Chalmers University of Technology, Gothenburg. He is now heading the Division of Antenna Systems at Department of Signals and Systems at Chalmers. Prof Kildal received two best paper awards for articles published in the IEEE Transactions on Antennas and Propagation, and he was the recipient of the 2011 Distinguished Achievements Award of the IEEE Antennas and Propagation Society. Kildal has authored an antenna textbook, and more than 150 journal articles and letters, most of them in IEEE or IET journals. He has designed two very large antennas, including the Gregorian dual-reflector feed of the Arecibo radiotelescope. He has invented several reflector antenna feeds, the latest being the so-called eleven antenna. Kildal is the originator of the concept of soft and hard surfaces, recently resulting in the gap waveguide, a new low-loss metamaterial-based transmission line advantageous in particular above 30 GHz. Kildal has received large individual grants from the Swedish research council VR and from the European Research Council ERC for research on gap waveguides. His research group has pioneered the reverberation chamber into an accurate Over-The-Air (OTA) measurement tool for antennas and wireless terminals subject to Rayleigh fading. This has been successfully commercialized in Bluetest AB.

4 Some Reflector and Feed Antenna Technologies that Made an Industrial Difference Originating from Radio Telescopes A personnel history with Keys to Success: Very basic EM principles, Characterization, Protection & Commercialization Per-Simon Kildal Distinguished lecturer of IEEE Antennas and Propagation Society

5 Purpose and content Show how basic science can give successful industrial spin-offs Three personal examples Reason: Innovations in industry requires also Out of box thinking Think different the Crazy Ones cause the big breakthroughs I hope that this talk can inspire young engineers/scientists to work with SKA and to commercialize ideas originating from SKA

6 Apple s Think different campaign/slogan in year Because the people who are crazy enough to think they can change the world, are the ones who do. Steve Jobs

7 Background of this talk Worked with Tor Hagfors, Cornell Univ. (died 2007) : PhD on EISCAT ionospheric radar : Projects on Arecibo radio telescope Several industrial projects : With companies in Norway Since 1989: With Ericsson, and own start-ups in Sweden Collaboration with Sander Weinreb, Caltech : On compact wideband Eleven feed for SKA Collaboration with Arnold van Ardenne & Co ar Astron in NL Since 2005: on efficiencies in focal plane arrays 2006: Arnold became Adjunct Professor at Chalmers 2007 SKADS Workshop: Contributions 2011: Marianna Ivashina and Rob Maaskant joined my research group.

8 Content Keys to success with inventions in my case Basic principles (wire grid, PEC/PMC grid) Characterization: Subefficiencies EISCAT VHF antenna (wire grid, two rods) Wire grid è ring for INMARSAT Ship Earth station antenna Gregorian feed of Arecibo radio telescope Corrugated horns è soft & hard surfaces èpec/pmc strip grids Mathematical model of line feeds è successful hat feed for radio links SKA decade bandwidth è logperiodic antennas è eleven feed Focal-plane arrays & MIMO arrays è decoupling efficiency

9 Keys to success with inventions in my case Projects with scientific instruments and interaction with their users Very basic EM principles Polarization-dependent PEC wire grid Polarization-independent PEC/PMC wire grid Rethinking of the logperiodic antenna BOR antennas Characterization We need to quantify good and bad Related to physical phenomena Protection Patent protection defines ownership Makes it easier to defend most places in the world Commercialization The ultimate proof of usefulness

10 Subefficiencies of Paraboloids and Cassegrain Antennas Similar formulas apply to general multi-reflector systems. Factorization of feed efficiency: e = e e e e Spillover, polarization, illumination and phase eff. a p s p p o l i l l f Spillover efficiency e sp Relative spillover power is given by 1 e sp Typically between db and -0.5 db. Major contributor to the antenna noise temperature.

11 Content Keys to success with inventions in my case Basic principles (wire grid, PEC/PMC grid) Characterization: Subefficiencies EISCAT VHF antenna (wire grid, two rods) Wire grid è ring for INMARSAT Ship Earth station antenna Gregorian feed of Arecibo radio telescope Corrugated horns è soft & hard surfaces èpec/pmc strip grids Mathematical model of line feeds è successful hat feed for radio links SKA decade bandwidth è logperiodic antennas è eleven feed Focal-plane arrays & MIMO arrays è decoupling efficiency

12 EISCAT VHF antenna

13 EISCAT line feed

14 Reflection and transmission properties of wire grids (non-gracing incidence) Canonical surface VERtical E-field polarization HORizontal Perfect Electric Conductor (PEC) STOP (reflects) STOP (reflects) Horizontal PEC wire grid GO (passes) STOP (reflects) Vertical PEC wire grid STOP (reflects) GO (passes) The lines in the table shows the direction of the wires in the grid.

15 Radiation pattern of line feed in transverse plane (1980): longitudinal and transverse polarisation The longitudnal rods work as a wire grid, shaping the far field of the longitudinal polarization, and not the transverse one.

16 Aperture efficiencies from transverse element patterns

17 Ca 1980: Small efficient resonant reflector antenna with dipole-disk feed The ring makes the E- and H- plane patterns equal (works as a conical surface of rings)

18 Resonant reflectors can be very efficient and influence system design strongly Radome with standard small reflector With optimum resonant reflector of same gain

19 In small primary-fed reflectors multiple reflections between feed and reflector can be used to increase gain. The encircled resonance was used.

20 Content Keys to success with inventions in my case Basic principles (wire grid, PEC/PMC grid) Characterization: Subefficiencies EISCAT VHF antenna (wire grid, two rods) Wire grid è ring for INMARSAT Ship Earth station antenna Gregorian feed of Arecibo radio telescope Corrugated horns è soft & hard surfaces èpec/pmc strip grids Mathematical model of line feeds è successful hat feed for radio links SKA decade bandwidth è logperiodic antennas è eleven feed Focal-plane arrays & MIMO arrays è decoupling efficiency

21 Radiotelescope in Arecibo

22 Platform with old 300 MHz line feed (left) and enclosure with dual-reflector feed inside (right)

23 Platform with old 300 MHz line feed (left) and enclosure with dual-reflector feed inside (right) : Methods for design and analysis of Gregorian dual-reflector feed

24 Broadband SOFT corrugated primary feed (Ying, A. Kishk and P-S. Kildal, 1995)

25 Constant beamwidth over GHz Aperture-field when used in arecibo threereflector system

26 Realization of soft and hard surfaces with corrugations (1988) (metamaterials) Soft STOP surface (left) Hard GO surface (right) Transverse air-filled corrugations Longitudinal dielectric-filled corrugations

27 / strip model of ideal soft and hard surfaces (2003) Ideal soft surface = polarization-independent STOP surface Ideal hard surface = polarization-independent GO surface Current fences strip period 0 Current lanes

28 2005: Table for comparing surfaces with respect to propagation along surfaces ERC funded GAP WAVEGUIDES are results of this table Canonical Surface PEC PMC E-field Polarization VER or TM HOR or TE PEC/PMC Strip grid PMC-type EBG grazing close to normal PMC The lines in the table shows the direction of the PEC/PMC wires in the grid. The EBG surface contains mushrooms (patches w/vias), illustrated as yellow squares.

29 Canonical surface (non-gracing incidence) Perfect Electric Conductor (PEC) VERtical E-field polarization HORizontal Horizontal PEC wire grid 2005: Table for comparing surfaces with respect to propagation along surfaces Vertical PEC wire grid Canonical Surface Gracing incidence PEC PMC E-field Polarization VER or TM HOR or TE PEC/PMC Strip grid

30 Hat feed is a result of Kildal s theoretical modeling av the Arecibo line feeds

31 Hat feed in ring-focus paraboloid (new phase efficiency) Low sidelobes Good efficiency The initial idea of the hat feed was based on the theoretical formuas in the paper on the previous page.

32 : 15 GHz military link project for EB NERA (low volume)

33 Hat fed reflectors have been in production since 2000 The below photos are from an improvement done in 2006.

34 More than hat antennas has been produced Started Comhat AB in Now these products are in LEAX Arkivator Telecom AB.

35 Content Keys to success with inventions in my case Basic principles (wire grid, PEC/PMC grid) Characterization: Subefficiencies EISCAT VHF antenna (wire grid, two rods) Wire grid è ring for INMARSAT Ship Earth station antenna Gregorian feed of Arecibo radio telescope Corrugated horns è soft & hard surfaces èpec/pmc strip grids Mathematical model of line feeds è successful hat feed for radio links SKA decade bandwidth è logperiodic antennas è eleven feed Focal-plane arrays & MIMO arrays è decoupling efficiency

36 Allan telescope Array a forerunner for SKA, 2003 Feed developed at UC Berkley

37 Idea behind Eleven feed new invention Two parallel dipoles over ground (Eleven configuration) from book by Christiansen and Högbom Radio Telescopes equal E- and H-plane patterns Beamwidth constant with frequency phase center is locked to the ground plane low far-out sidelobes and backlobes. Decade bandwidth by Logperiodic Folded dipoles

38 Log-periodic feeds for reflector antennas, 2003 Example: Lowest frequency 500 MHz Old technology New technology Background: UWB antennas = logperiodic The Eleven antenna: 11 times smaller -and better Breakthrough in wideband technology

39 Design of GMRT Eleven feed by Yogesh Karandikar on Master project Autumn 2006

40 Assembled hardware and drawing of 1-14 GHz Eleven feed

41 Directivity 11 dbi over more than a decade bandwidth And 11 > decade

42 Co- and crosspolar patterns in 45 deg plane total and with removed higher order f variations amplitude (db) GHz 4.1GHz 4.2GHz 4.3GHz 4.4GHz 4.5GHz 4.6GHz 4.7GHz 4.8GHz 4.9GHz Relative level [dbi] GHz 4.10 GHz 4.20 GHz 4.30 GHz 4.40 GHz 4.50 GHz 4.60 GHz 4.70 GHz 4.80 GHz 4.90 GHz theta (deg) θ [ o ] A new subefficiency characterizes purity of feed pattern BOR1 efficiency)

43 Sub-efficiencies from measured radiation patterns Looks good, except for BOR1 efficiency below 2.5 GHz and above 9 GHz BOR1 efficiency is power lost in sidelobes due to higher order f variations. Efficiency (db) e sp e BOR1 e pol e ill -3.5 e φ e ap Frequency (GHz)

44 Leightweight MHz Eleven antenna version Weight 8.5 kg 800 mm

45 Content Keys to success with inventions in my case Basic principles (wire grid, PEC/PMC grid) Characterization: Subefficiencies EISCAT VHF antenna (wire grid, two rods) Wire grid è ring for INMARSAT Ship Earth station antenna Gregorian feed of Arecibo radio telescope Corrugated horns è soft & hard surfaces èpec/pmc strip grids Mathematical model of line feeds è successful hat feed for radio links SKA decade bandwidth è logperiodic antennas è eleven feed Focal-plane arrays & MIMO arrays è decoupling efficiency

46 We are going to develop new technology for both antennas and receivers for the SKA, says John Conway, deputy director for Onsala Space Observatory. Science/Engineering management - Electromagne1c design of wideband feeds for reflector antennas - Modeling of antenna-receiver systems and calibra1on of radio telescopes 2 from SA:

47 Research efforts towards characterizaoon of Mutual Coupling Effects in dense Focal Plane Arrays 2002 First studies by M. Ivashina & A. van Ardenne (2002) Invited lecture by Kildal on the characterizaoon of reflector antennas feeds at the SKADS Marie Curie workshop, Dwingeloo 2007 IntroducOon of the unified decoupling efficiency for array feeds by the CHALMERS-ASTRON team (M. Kehn, M. Ivashina, P.-S. Kildal, and R. Maaskant) Since that Ome: - Several common journal and conference papers, - FP7 MCA-VINNMER Fellowship (co-)funded by ASTRON and Chalmers, - 2 PhD projects on FPAs (co-)funded by the Swedish and SA naoonal research councils Measurements of the FPA decoupling efficiency in the BlueTest reverbera1on chamber in Gothenburg

48 CharacterizaOon in rich isotropic mulopath in reverberaoon chamber Since 2010 Spin-off company Bluetest has success in market. Has now 35 employees and annual turnover of 90 Mkr

49 Content Keys to success with inventions in my case Basic principles (wire grid, PEC/PMC grid) Characterization: Subefficiencies EISCAT VHF antenna (wire grid, two rods) Wire grid è ring for INMARSAT Ship Earth station antenna Gregorian feed of Arecibo radio telescope Corrugated horns è soft & hard surfaces èpec/pmc strip grids Mathematical model of line feeds è successful hat feed for radio links SKA decade bandwidth è logperiodic antennas è eleven feed Focal-plane arrays & MIMO arrays è decoupling efficiency

50 Keys to success with inventions in my case Projects with scientific instruments and interaction with their users Very basic EM principles Polarization-dependent PEC wire grid Polarization-independent PEC/PMC wire grid Rethinking of the logperiodic antenna BOR antennas Characterization We need to quantify good and bad Related to physical phenomena Protection Patent protection defines ownership Makes it easier to defend most places in the world Commercialization The ultimate proof of usefulness

51 Canonical surface (non-gracing incidence) VER1cal E-field polariza1on HORizontal Perfect Electric Conductor (PEC) Horizontal PEC wire grid 2005: Table for comparing surfaces with respect to propagation along surfaces Ver1cal PEC wire grid Canonical Surface Gracing incidence PEC PMC E-field Polarization VER or TM HOR or TE PEC/PMC Strip grid

52 I hope that this talk can inspire young engineers/scientists to work with SKA and to commercialize ideas originating from SKA

53 References P.-S. Kildal, Some Reflector and Feed Antenna InvenOons that Made a Difference, Africon 2013, MauriOus (presentaoon given as DisOnguished Lecturer of IEEE APS Society) [1] P. S. Kildal, "FactorizaOon of the feed efficiency of paraboloids and Cassegrain antennas," IEEE TAP, vol. AP-33, pp , [2] P. Kildal and Z. Sipus, "ClassificaOon of RotaOonally Symmetric Antennas as Types BOR0 and BOR1," IEEE AP Magazine, vol. 37, p. 114, [3] P. S. Kildal, "Combined E- and H-plane phase centers of antenna feeds," IEEE TAP, vol. AP-31, pp , [4] M. V. Ivashina, M. Kehn, P. S. Kildal, and R. Maaskant, "Decoupling efficiency of a wideband vivaldi focal plane array feeding a reflector antenna," IEEE TAP, vol. 57, pp , [5] M. N. M. Kehn, M. V. Ivashina, P. S. Kildal, and R. Maaskant, "DefiniOon of unifying decoupling efficiency of different array antennas: Case study of dense focal plane array feed for parabolic reflector," AEU-InternaOonal Journal of Electronics and Comm., vol. 64, pp , [6] P. S. Kildal, "Aperture efficiency and line feed phase center of parabolic cylindrical reflector antenna," IEEE TAP, vol. AP-32, pp , [7] P. S. Kildal, "RadiaOon characterisocs of the EISCAT VHF parabolic cylindrical reflector antenna," IEEE TAP, vol. AP-32, pp , [8] P. S. Kildal and S. A. Skymemyr, "Dipole-disk antenna with beam-forming ring," IEEE TAP, vol. AP-30, pp , [9] E. Lier and P. S. Kildal, "Son and hard horn antennas," IEEE TAP, vol. 36, pp , [10] P. S. Kildal, "DefiniOon of aroficially son and hard surfaces for electromagneoc waves," Electronics Lemers, vol. 24, pp , [11] P. S. Kildal, "Gaussian beam model for aperture-controlled and flareangle-controlled corrugated horn antennas," IEE Proceedings H (Microwaves, Antennas and PropagaOon), vol. 135, pp , [12] Z. Ying, A. A. Kishk, and P. S. Kildal, "Broadband compact horn feed for prime-focus reflectors," Electronics Lemers, vol. 31, pp , 1995.

54 More references [13] P. S. Kildal, K. Jakobsen, and K. Sudhakar Rao, "Meniscus-lens-corrected corrugated horn: a compact feed for a Cassegrain antenna," IEE Proceedings H (Microwaves, OpAcs, Antennas), vol. 131, pp , [14] P. S. Kildal and K. R. Jakobsen, "Scalar horn with shaped lens improves Cassegrain efficiency," IEEE TAP, vol. AP-32, pp , [15] P. S. Kildal, "Study of element pamerns and excitaoons of the line feeds of the spherical reflector antenna in Arecibo," IEEE TAP, vol. AP-34, pp , [16] T. Ulversoy and P. S. Kildal, "RadiaOon from slots in aroficially son and hard cylinders," IEEE TAP, vol. 37, pp , [17] P. S. Kildal, "The hat feed: a dual-mode rear-radiaong waveguide antenna having low cross polarizaoon," IEEE TAP, vol. AP-35, pp , [18] P. S. Kildal and T. Jensen, "Efficient small reflector with hat feed," ICAP 89, 4-7 April 1989, London, UK, 1989, pp [19] J. Hansen, A. A. Kishk, P. S. Kildal, and O. Dahlsjo, "High performance reflector hat antenna with very low sidelobes for radio-link applicaoons," in IEEE APS 1995, New York, NY, USA, 1995, pp [20] J. Yang and P.-S. Kildal, "CalculaOon of ring-shaped phase centers of feeds for ring-focus paraboloids," IEEE TAP, vol. 48, pp , [21] M. Denstedt, T. Ostling, Y. Jian, and P. S. Kildal, "Tripling bandwidth of hat feed by geneoc algorithm opomizaoon," in 2007 IEEE APS, Piscataway, NJ, USA, 2008, pp [22] R. Olsson, P. S. Kildal, and S. Weinreb, "The eleven antenna: a compact low-profile decade bandwidth dual polarized feed for reflector antennas," IEEE TAP, vol. 54, pp , [23] P. S. Kildal, R. Olsson, and Y. Jian, "Development of three models of the eleven antenna: a new decade bandwidth high performance feed for reflectors," in EuCAP 2006, Noordwijk, Netherlands. [24] J. Yang, M. Pantaleev, P.-S. Kildal, B. Klein, Y. Karandikar, L. Helldner, N. Wadefalk, C. Beaudoin, "Cryogenic 2-13 GHz Eleven Feed for Reflector Antennas in Future Wideband Radio Telescopes", IEEE TAP, Vol. 59, No. 6, pp