Barth, MJ, Mcleod, RR & Ziolkowski, RW 1992, 'A Near and Far-Field Projection Algorithm for Finite-Difference Time-Domain Codes', Journal of Electromagnetic Waves and Applications, vol. 6, no. 1-6, pp. 5-18.
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The class of problems to which the Finite-Difference Time-Domain (FDTD) method can be applied is extended through the use of near and far-field projection techniques. These methods are developed by applying the equivalence principle to a surface within the FDTD problem space. Algorithms are found to project the equivalent electric and magnetic currents on this surface to any point in space either in the time or the frequency domains. A summary of extensive validation and error checking results is presented which shows the routines to be robust and accurate to within a few percent. As a result, the FDTD approach can be applied to a number of previously impractical problems. © 1992, VSP. All rights reserved.
Barth, MJ, McLeod, RR & Ziolkowski, RW 1992, 'A near and far-field projection algorithm for finite-difference time-domain codes', Journal of Electromagnetic Waves and Applications, vol. 6, no. 1-4, pp. 5-18.
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The class of problems to which the Finite-Difference Time-Domain (FDTD) method can be applied is extended through the use of near and far-field projection techniques. These methods are developed by applying the equivalence principle to a surface within the FDTD problem space. Algorithms are found to project the equivalent electric and magnetic currents on this surface to any point in space either in the time or the frequency domains. A summary of extensive validation and error checking results is presented which shows the routines to be robust and accurate to within a few percent. As a result, the FDTD approach can be applied to a number of previously impractical problems. © 1992 VSP.
BARTH, MJ, MCLEOD, RR & ZIOLKOWSKI, RW 1992, 'A NEAR AND FAR-FIELD PROJECTION ALGORITHM FOR FINITE-DIFFERENCE TIME-DOMAIN CODES', JOURNAL OF ELECTROMAGNETIC WAVES AND APPLICATIONS, vol. 6, no. 1, pp. 5-18.
Bird, TS & Sroka, C 1992, 'Design of the KU-band antennas for the Galaxy HS601C satellites', Journal of Electrical and Electronics Engineering, Australia, vol. 12, no. 3, pp. 267-273.
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Outcomes of a study undertaken by CSIRO on the six possible shaped beams for the Galaxy HS601C satellites are described. These satellites will provide C- and Ku-band communications to continental USA and neighbouring islands. Of especial concern in the study was the effect on performance of mutual coupling between the multi-mode horns in the feed arrays for the reflectors which generate the shaped beams. Mutual coupling influences the reflection coefficient at the horn inputs as well as the directivity of the shaped beam. After a brief description of the antenna geometry, methods used to analyse the antennas are outlined. Results are presented for possible antenna designs with and without mutual coupling in the feed array. We describe some techniques employed to optimize the array beamforming networks. Due to practical considerations it was possible to change only some of the beamforming network couplers and the impact of shaped beam design with a reduced set of couplers is discussed.
Donnelly, R & Ziolkowski, R 1992, 'A method for constructing solutions of homogeneous partial differential equations: Localized waves', Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 437, no. 1901, pp. 673-692.
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We introduce a method for constructing solutions of homogeneous partial differential equations. This method can be used to construct the usual, well-known, separable solutions of the wave equation, but it also easily gives the non-separable localized wave solutions. These solutions exhibit a degree of focusing about the propagation axis that is dependent on a free parameter, and have many important potential applications. The method is based on constructing the space-time Fourier transform of a function so that it satisfies the transformed partial differential equation. We also apply the method to construct localized wave solutions of the wave equation in a lossy infinite medium, and of the Klein-Gordon equation. The localized wave solutions of these three equations differ somewhat, and we discuss these differences. A discussion of the properties of the localized waves, and of experiments to launch them, is included in the Appendix. © 1992 The Royal Society.
Guo, YJ & Barton, SK 1992, 'A High-Efficiency Quarter-Wave Zone Plate Reflector', IEEE Microwave and Guided Wave Letters, vol. 2, no. 12, pp. 470-471.
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A multilayered quarter-wave zone plate reflector antenna operating in the microwave range is presented. The theory for designing the reflector and experimental results are given. An efficiency of 55% was obtained with a prototype reflector antenna. © 1992 IEEE
Hernandez, JE, Ziolkowski, RW & Parker, SR 1992, 'Synthesis of the driving functions of an array for propagating localized wave energy', Journal of the Acoustical Society of America, vol. 92, no. 1, pp. 550-562.
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This paper presents a framework for designing the driving functions of an array of radiating elements given a scalar representation of the desired propagating field at a finite number of remote spatial locations. Based on a point source propagation model in a homogeneous media, the relationship between the driving functions and the resulting field leads to a system of linear equations in the frequency domain. A least-squares solution to the inverse problem is obtained by solving the system of linear equations for the unknown array driving functions. The proposed framework is suitable for designing array driving functions that could be used to generate 'source- free' (homogeneous) solutions to the wave equation. This paper focuses on the use of the proposed technique for calculating array driving functions for generating localized wave energy. Two cases are discussed; one based on a source-free solution to the wave equation, and the other based on a numerical traveling impulse function. The results are compared to the beam generated by driving the array uniformly with a continuous-wave (cw) signal.
Veitch, D 1992, 'Windows of stability in control chaos', Circuits and Systems I: Fundamental Theory and Applications, IEEE Transactions on, vol. 39, pp. 808-819.
Vengsarkar, AM, Besieris, IM, Shaarawi, AM & Ziolkowski, RW 1992, 'Closed-form, localized wave solutions in optical fiber waveguides', Journal of the Optical Society of America A: Optics and Image Science, and Vision, vol. 9, no. 6, pp. 937-949.
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A novel bidirectional decomposition of exact solutions to the scalar wave equation has been shown to form a natural basis for synthesizing localized-wave (LW) solutions that describe localized, slowly decaying transmission of energy in free space. We present a theoretical feasibility study that shows the existence of LW solutions in optical fiber waveguides. As with the free-space case, these optical waveguide LW solutions propagate over long distances, undergoing only local variations. Four different source modulation spectra that give rise to solutions similar to focus wave modes, splash pulses, the scalar equivalent of Hillion's spinor modes, and the modified power spectrum pulses are considered. A detailed study of the modified power spectrum pulse is performed, the practical issues regarding the source spectra are addressed, and the distances over which such LW solutions maintain their nondecaying nature are quantified. © 1992 Optical Society of America.
ZIOLKOWSKI, RW 1992, '[title field missing]', J. Opt. Soc. Am. A, vol. 9.
Ziolkowski, RW 1992, 'Properties of Electromagnetic Beams Generated by Ultra-Wide Bandwidth Pulse-Driven Arrays', IEEE Transactions on Antennas and Propagation, vol. 40, no. 8, pp. 888-905.
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The characteristics of the beams generated by ultra-wide bandwidth electromagnetic systems are central to their practical applications. These characteristics include the rate of beam divergence, the beam intensity, and the energy efficiency. Analytical bounds on the characteristics of beams generated by an arbitrary pulse-driven array are derived and supported with numerical calculations. These bounds extend the meaning of near-field distances or diffraction lengths to the situation where the array driving functions can be broad-band-width signals. Particular attention is given to transmitting and receiving array systems which consist of elements that are not large in comparison to the shortest wavelength of significance contained in the signals driving them. The output signals of such systems are time derivatives of the input driving functions. They constitute higher-order beams whose coherence properties are degraded more slowly by diffraction than lower-order beams. The bounds define the extent of these enhancements. It is further shown that for certain measures of performance involving these beam characteristics, a localized wave pulse-driven array can outperform similar continuous-wave-driven arrays. A new type of array is required to realize these localized wave effects—one that has independently addressable elements. The enhanced localization effects are intimately coupled to the proper spatial distribution of broad-bandwidth signals driving the array; i.e., by controlling not only the amplitudes, but also the frequency spectra of the pulses driving the array. © 1992 IEEE
ZIOLKOWSKI, RW & JUDKINS, JB 1992, 'PROPAGATION CHARACTERISTICS OF ULTRAWIDE-BANDWIDTH PULSED GAUSSIAN BEAMS', JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION, vol. 9, no. 11, pp. 2021-2030.
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