Bird, TS 1984, 'Comparison of Asymptotic Solutions for the Surface Field Excited by a Magnetic Dipole on a Cylinder', IEEE Transactions on Antennas and Propagation, vol. 32, no. 11, pp. 1237-1244.
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In the analysis of mutual coupling in apertures on a convex surface, the surface field due to a magnetic dipole on a large conducting cylinder is an important canonical problem. Over the years a number of approximate asymptotic solutions have been described in the literature. In this paper the accuracy of five of the best solutions currently available is tested by comparing them with the exact modal solution. This comparison is accomplished by placing the modal solution in a more efficient form for numerical evaluation. From a study of four ray trajectories on cylinders of radius 1.5171 and four wavelengths it is concluded that two complementing solutions due to Boersma and Lee and the author have best overall accuracy. The former solution is most accurate near the source and in the paraxial region while the latter is best far from the source and off axis. The worst case errors observed for the test trajectories on the four wavelength cylinder were approximately 1 dB in magnitude and 3° in phase for the Boersma-Lee solution and 0.5 dB and 4°, respectively, for the author's solution. Generally the errors are considerably less than these values. © 1984 IEEE
JOHNSON, WA & ZIOLKOWSKI, RW 1984, 'THE SCATTERING OF AN H-POLARIZED PLANE-WAVE FROM AN AXIALLY SLOTTED INFINITE CYLINDER - A DUAL SERIES APPROACH', RADIO SCIENCE, vol. 19, no. 1, pp. 275-291.
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Ziolkowski, RW & Deschamps, GA 1984, 'Asymptotic evaluation of high‐frequency fields near a caustic: An introduction to Maslov's method', Radio Science, vol. 19, no. 4, pp. 1001-1025.
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It is well known that the geometrical optics approximation, generally valid for high‐frequency fields, fails in the vicinity of a caustic. A systematic procedure of V. P. Maslov that remedies this situation will be reviewed in this paper. Maslov's method makes use of a representation of the geometrical optics field in the phase space M = X × K, where a point m = (x, k) is a pair of a position vector x ε X and a wave vector k ε K. A Lagrangian submanifold of M, Λ, that lies in the dispersion surface and is a union of the phase space trajectories selected by the initial conditions is constructed. It can be considered as a global representation of the phase. The phase space amplitudes (half densities) satisfy transport equations defined along those trajectories in Λ. Since trajectories in M never form a caustic, a globally defined amplitude can be established on Λ. The field on X is related to the resultant field on Λ by the “canonical operator,” an operator introduced by Maslov. It generates an integral form of the solution near a caustic that can be evaluated analytically, numerically, or with uniform asymptotic techniques. Away from the caustic it recovers the geometrical optics field. Alternatively, the phase space field can be projected on a hybrid space Y where some of the space coordinates have been replaced by the corresponding wave vector components. For any caustic point in X, one such hybrid space Y where this projection does not encounter a caustic exists. A geometrical optics field results in Y that is related to the original in X by an asymptotic Fourier transform. The solution in X near a caustic can be represented as the Fourier transform to X of that hybrid space geometrical optics solution. These techniques are illustrated with two simple but revealing problems: continuation of the field through a fold caustic in a linear layer medium and through a caustic with a cusp point in a homogeneous medium. This paper is not subject to U.S. copyright. Publi...
ZIOLKOWSKI, RW & DESCHAMPS, GA 1984, 'THE ASYMPTOTIC POINCARE LEMMA AND ITS APPLICATIONS', SIAM JOURNAL ON MATHEMATICAL ANALYSIS, vol. 15, no. 3, pp. 535-558.
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ZIOLKOWSKI, RW, JOHNSON, WA & CASEY, KF 1984, 'APPLICATIONS OF RIEMANN-HILBERT PROBLEM TECHNIQUES TO ELECTROMAGNETIC COUPLING THROUGH APERTURES', RADIO SCIENCE, vol. 19, no. 6, pp. 1425-1431.
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Bird, TS, James, GL, Poulton, GT & Thomas, BMA 1984, 'ANTENNA DESIGN PRINCIPLES FOR SATELLITE COMMUNICATIONS.', National Conference Publication - Institution of Engineers, Australia.
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Antenna systems used in satellite communications are the vital link in the transfer of information between the ground station and the satellite and also between satellites. The increasing sophistication of each successive generation of satellites has meant that their antenna requirements have become more demanding. Further, with the reduction in the angular spacing between satellites in the geostationary orbit, tighter specifications are being placed on the earth station antenna. In this paper the authors review the antenna technology that has been developed to meet these demands. Current and projected antenna systems will be discussed, with reference to the INTELSAT and AUSSAT satellite systems where applicable.