The development of a C-Band contoured beam antenna for the coverage of the People's Republic of China is described. The antenna applies two polarisation sensitive reflector shells which are mounted behind each other. The orthogonally gridded reflectos of 2 m diameter are fed by two 7-horn clusters of corresponding linear polarisations, providing both combined transmit (3.7 -4.2 GHz) and receive (5.925 -6.425 GHz) functions. Each array consists of diagonal horns followed by waveguide diplexers which are fed by two beamforming networks (Tx and Rx respectively) in coaxial technique (barline). A dual mode transmit network provides two independent input ports. The engineering model of this antenna will be completed in 1989. First breadboard results of the most critical components of the feedsystem are given. JIBQDUTflNIn March 1988 MBB was awarded a contract from the People's Republic of China for the development of some important subsystems for the Chinese communication satellite DFH-3. One of the key elements of this contract is the development of the C-band communication antenna subsystem. The combined transmit-receive antenna enables operation of 24 channels in 500 MHz bandwidth by applying polarisation diversity. Part of this work was sponsored by the European Space Agency (ESA). REQUIREMENTSThe design objective was to realise a contoured beam coverage of the People's Republic of China with maximum edge of coverage gain for both the transmit (3.7 -4.2 GHz) as well as the receive (5.925 -6.425 GHz) frequency band. A minimum gain of about 27 dBi is required in both bands for at least 90 % of the coverage area. This value has to be achieved taking into account a satellite pointing accuracy of +/-0.1 degree. Full polarisation reuse is necessary to be able to receive and transmit 24 40-MHz channels in 500 MHz bandwidth. A minimum cross-polarisation isolation of 33 dB is required in the service zone. Furthermore two independent Tx-input ports are necessary for each linear polarisation to be able to multiplex 12 40-MHz channels without having to use a contiguous output multiplexer. A minimum decoupling of 40 dB between Tx-and Rx-ports is specified and a maximum VSWR of 1.2 :1 for all input ports. Very stringent mechanical requirements are specified for the antenna subsystem. The most critical is the first Eigen-frequency specification of more then 35 Hz (folded configuration) in combination with the maximum mass requirement of 41 kg. Furthermore a maximum pointing uncertainty of 0.05 degr. for the complete antenna subsystem has to be realised.
4] Spann, R.: A two-dimensional correlation property of pseudorandom maximal length sequences. Proc. IEEE, VoL S3 (1965) p. 2137. [51 Fenimore, E.E.; Cannon, T.M.: Coded aperture imaging with uniformly redundant arrays. Applied Optics, VoL 17 (1978) pp. 337-347. [6] Sckraeder, M.R.: Diffuse sound reflection by maximum-fength sequences. J. Aconst Soc. Am, VoL 57 (1975) pp. 149-150. [7] Goby, M.J.E.: The meritfactor of long low autocorrelation binary sequences. IEEE Trans. Inform. Theory, VoL IT-28 (1982) pp. 543-549. [8] Mac Williams, F. J.; Sloane. N. J. A.: Pseudo-random sequences and arrays. Proc. IEEE, VoL 64 (1976) pp. 1715-1729. [9] Antweiler, M.; Bömer, L.; Luke, H.D.: Perfect Ternary Arrays. Proposed for publication in IEEE Trans. Inform. Theory. [10] Luke, H. D.: Sequences and arrays with perfect periodic correlation. IEEE Trans. Aerosp. Electron. Syst., VoL AES-24 (1988) pp. 287-294. [11] Calabro, D.; Wolf, J.K.: On the synthesis of two-dimensional arrays »im desirable correlation properties. Inform. Contr, VoL 11 (1968) pp. 537-560. [12] Chan, Y.K.; Sin, M.K.; Tong. P.: Two-dimensional binar) arrays with good autocorrelation. Inform, a. Contr., VoL 42 (1979) pp. 125-130. [13] Bömer. L.; Antweikr, M.: Perfect binary arrays with 36 elements. Electron. Lett, VoL 23 (1987) pp. 730-732. [14] Bömer, L.; Antweiler, M.: Two-dimensional perfect binary arrays with 64 dements. Accepted for publication in IEEE Trans. Information Theory. [15] Wild. P.: Infinite families of perfect binary arrays. Electron. Lett, VoL 24 (1988) pp. 845-847. [16] Jedwab, J.; Mitchell, C: Construction new perfect binary arrays. Electron. Lett, VoL 24 (1988) pp. 650-652. [17] Luke, H.D.; Bömer, L.: Perfect binary arrays. To be published in: Signal Processing, VoL 16 (1989). [18] Bamnen, L.D.: Cyclic difference sets. Berlin: Springer Verlag, 1971. [19] Kopiknich, L. E.: On perfect binary arrays. Electron. Lett, VoL 24 (1988) pp. [20] [21] Lemple, A'.; Cohn, M.; Eastman, W.L.: A class of balanced binary quences with optimal autocorrelation properties. IEEE Trans. Abstract:The eigenfunction expansion method is used to solve the field problem of rectangular-coaxial lines and step discontinuities. The programme package developed has been applied to design several TEM-branchline couplers. The performance measured coincides well with the theoretical predictions. Übersicht:Orthpgonalentwicklung nach Eigenfunktion wird zur Lösung der Randwertprobleme in rechteckkoaxialen Leitungen und Strukturen mit sprunghafter Breitenänderung angewandt. Entsprechende Programme sind getestet und erfolgreich zum Entwurf von mehreren TEM-Branch-Line-Kopplern eingesetzt worden. Die gemessenen Kopplercharakteristiken stimmen gut mit den theoretischen Voraussagen überein. Für die Dokumentation :Orthogonalentwicklung / rechteck-koaxiale Leitung / TEM-Leitung / Leitungsdiskontinuität/ TEM-Branch-Line-Koppler / Filter
In this paper we compare branch-line couplers for Ka-band multi feed satellite antennas in waveguide and barline technology. For the comparison the simulated RF performance is considered as well as mechanical, thermal and accommodation aspects.
Übersicht: Die Methode der Orthogonalentwicklung wird zur Behandlung von Wellenleiterdiskontinuitäten, insbesondere von Barline-Breitenänderungen, angewendet. Mit den entwickelten Programmen wurden zahlreiche Mikrowellenkomponenten, wie BarUne-Koppler oder Wärmesenken, mit sehr gutem Übertragungsverhalten entworfen und realisiert Neue Anwendungen mit den Programmen wurden erschlossen. Für den kompakten Septum-Polarisator werden das berechnete und gemessene, für einen Dualband-Hohlleiterhybridkoppler das berechnete Übertragungsverhalten gezeigt. Die Leistungsfähigkeit der benutzten Methode wird durch die sehr gute Übereinstimmung der berechneten mit den gemessenen Ergebnissen belegt.Abstract: The method of mode matching is applied to solve the field problem of discontinuities encountered especially in rectangular coaxial barline structures. Using the developed program package many useful microwave components, like coupler and heat sink, with excellent performances were designed and built in satellite antennas. For new applications, like compact septum polarizer and waveguide hybrid coupler, the predicted performances are shown. The excellent coincidence between measurements and predictions demonstrates the capability and competitiveness of the program package.
r i v a t e Bag, Auckland New Zealand.This work follows from [ l ] where s i n g u l a r i n t e g r a l e q u a t i o n theory has been used to obtain leading terms of t h e t o t a l c u r r e n t d i s t r i b u t i o n on thick tubular antennas. Two forms of t h e i n t e g r a l e q u a t i o n f o r t h e c u r r e n t on a perfectly conducting tubular transmitting antenna, a s shown i n F i g u r e 1, have been i n v e s t i g a t e d , namely,0 where the s o u r c e f u n c t i o n f o r d e l t a -f u n c t i o n e x c i t a t i o n w i t h n o r o t a t i o n a l v a r i a t i o n i s To s o l v e (1) and (2), the logarithmic term i n b o t h t h e k e r n e l and the source function i s i s o l a t e d and t h e n o n s i n g u l a r p a r t s approximated by f i n i t e Chebyshev expansions. I n t h e c a s e of (11, t h e v a r i a b l e r t $ ( t > = dl(t) d t + H2 lo I ( t o ) d t o is introduced and the equation i s c a s t i n t o a s i n g u l a r i n t e g r a l 156
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