Bateman, D, Hay, S, Bird, T & Sanagavarapu, AM 1995, 'Method Of Moments Analysis Of Offset-reflector Antennas', Electronics Letters, vol. 31, no. 22, pp. 1889-1890.
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The authors apply the method of moments to analyse the surface currents and radiation patterns of offset-reflector antennas. For a small disk, the convergence of the techniques is compared with an exact solution. The results presented for an offset refle
CANNING, J & SCEATS, MG 1995, 'TRANSIENT GRATINGS IN RARE-EARTH-DOPED PHOSPHOSILICATE OPTICAL FIBERS THROUGH PERIODIC POPULATION-INVERSION', ELECTRONICS LETTERS, vol. 31, no. 7, pp. 576-577.
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CANNING, J, SCEATS, MG, INGLIS, HG & HILL, P 1995, 'TRANSIENT AND PERMANENT GRATINGS IN PHOSPHOSILICATE OPTICAL FIBERS PRODUCED BY THE FLASH CONDENSATION TECHNIQUE', OPTICS LETTERS, vol. 20, no. 21, pp. 2189-2191.
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Cucchiara, R, Distefano, L & Piccardi, M 1995, 'Detection Of Circular Objects By Wave-propagation On A Mesh-connected Computer', Journal Of Parallel And Distributed Computing, vol. 31, no. 1, pp. 77-87.
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Circular objects can be detected in low-contrast and/or blurred images by propagating intensity values according to a two-dimensional wave equation and then finding peaks generated by constructive interference. The paper proposes a parallel algorithm for
Davidson, DB & Ziolkowski, RW 1995, 'A connection machine (CM‐2) implementation of a three‐dimensional parallel finite difference time‐domain code for electromagnetic field simulation', International Journal of Numerical Modelling: Electronic Networks, Devices and Fields, vol. 8, no. 3-4, pp. 221-232.
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This paper describes a parallel three‐dimensional finite difference time‐domain (FDTD) code for electromagnetic field simulation that has been developed for the Connection Machine (CM‐2). The CM‐2 is briefly discussed. Then the FDTD method is reviewed using a one‐dimensional example, and the extensions required for the 3‐D case are outlined. The parallelization of the FDTD method is considered, and a simple analytical timing model is dervied. This model predicts the efficiency of the parallelized algorithm as a function of grain size. Some specific points relating to the implementation of the parallel FDTD algorithm in Fortrans‐90 on the CM‐2 are discussed. Timing data for the parallel 3‐D FDTD code measured on a CM‐2 is presented and compared qualitatively with the theoretical model. These results are then put into perspective for a particular computations electromagnetics problem, viz. the development of software tools for full‐wave modelling of 3‐D optical devices. Finally, we draw some conclusions about this work. Copyright © 1995 John Wiley & Sons, Ltd
Dutkiewicz, E & Anido, G 1995, 'Optimisation of distributed exchange control systems', ATR. Australian telecommunication research, vol. 29, no. 2, pp. 1-13.
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New telecommunications services have emerged which will place quite disparate processing demands on the control systems of exchanges and the optimal system configuration will depend on the call mix to be supported by the exchange. A cost effective distributed control system design in the ISDN and IN environments can be achieved by combining optimal placement of software functionality and optimal choice of capacities for the processing elements. Two control system models based on queueing networks and able to capture the features of the system at different levels of detail are developed and used to produce distributed control system optimisation algorithms. These algorithms can assist system designers in producing optimal control systems which are required to satisfy particular uniform load specifications and performance constraints. Simple examples indicate the range of applicability of the developed algorithms.
Guo, YJ & Barton, SK 1995, 'Analysis of One-Dimensional Zonal Reflectors', IEEE Transactions on Antennas and Propagation, vol. 43, no. 4, pp. 385-389.
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A one-dimensional zonal reflector is a conducting surface which is uniform in one direction and has a zonal profile in the other. Similar to a cylindrical reflector, it converts a cylindrical wave from a line-source into an outgoing plane wave. In this paper, the radiation performance of such reflectors with TM-wave illumination is analyzed by the method of moments (MoM). The influence of corner diffraction and zoning on the sidelobe level is investigated. Three types of configurations are considered, which include the parabolic zonal reflector and two stepwise zonal reflectors of different configurations. It is found that corner diffraction makes a significant contribution to the sidelobe level, but zoning intrinsically raises the far-out sidelobes. Numerical results show that the near-in sidelobes of the stepwise zonal reflector can be significantly decreased by adjusting the geometrical configuration. © 1995 IEEE
Guo, YJ & Barton, SK 1995, 'Phase Correcting Zonal Reflector Incorporating Rings', IEEE Transactions on Antennas and Propagation, vol. 43, no. 4, pp. 350-355.
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An array of Conducting elements printed on a grounded dielectric substrate functions as an electromagnetic phase shifter. With a fixed substrate and a given operating frequency, the phase shift is determined by the array parameters. In the paper, the spectral domain moment method model for analyzing homogeneous reflective phase shifters with conducting rings as elements is presented, and numerical and experimental results are given. A novel phase correcting Fresnel zonal reflector based on this model is reported. A 43% maximum antenna efficiency and -22 dB sidelobe level were measured in X-band. The bandwidth of the reflector is estimated to be greater than 10%. © 1995 IEEE
GUO, YJ & BARTON, SK 1995, 'PHASE EFFICIENCY OF THE REFLECTIVE ARRAY ANTENNA', IEE PROCEEDINGS-MICROWAVES ANTENNAS AND PROPAGATION, vol. 142, no. 2, pp. 115-120.
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HILL, PC, ATKINS, GR, CANNING, J, COX, GC & SCEATS, MG 1995, 'WRITING AND VISUALIZATION OF LOW-THRESHOLD TYPE-II BRAGG GRATINGS IN STRESSED OPTICAL FIBERS', APPLIED OPTICS, vol. 34, no. 33, pp. 7689-7694.
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James, GL, Clark, PR, Graves, GR & Bird, TS 1995, 'S/X-band feed for the Tasmanian earth resources satellite station (TERSS)', Journal of Electrical and Electronics Engineering, Australia, vol. 15, no. 4, pp. 307-314.
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The development of the complex feed system for the Tasmanian Earth Resources Satellite Station (TERSS) is described. The feed system provides simultaneous S/X-band operation with dual polarisation and tracking capabilities within a compact coaxial waveguide arrangement. Extensive use of theoretical methods was necessary to achieve the required performance and the agreement with measured data verified the theoretical designs.
JANOS, M & CANNING, J 1995, 'PERMANENT AND TRANSIENT RESONANCES THERMALLY-INDUCED IN OPTICAL-FIBER BRAGG GRATINGS', ELECTRONICS LETTERS, vol. 31, no. 12, pp. 1007-1009.
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Judkins, JB & Ziolkowski, RW 1995, 'Finite-difference time-domain modeling of nonperfectly conducting metallic thin-film gratings', Journal of the Optical Society of America A: Optics and Image Science, and Vision, vol. 12, no. 9, pp. 1974-1983.
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A simulation tool based on the finite-difference time-domain (FDTD) technique is developed to model the electromagnetic interaction of a focused optical Gaussian beam in two dimensions incident on a simple model of a corrugated dielectric surface plated with a thin film of realistic metal. The technique is a hybrid approach that combines an intensive numerical method near the surface of the grating, which takes into account the optical properties of metals, with a free-space transform to obtain the radiated fields. A description of this technique is presented along with numerical examples comparing gratings made with realistic and perfect conductors. In particular, a demonstration is given of an obliquely incident beam focused on a uniform grating and a normally incident beam focused on a nonuniform grating. The gratings in these two cases are coated with a negative-permittivity thin film, and the scattered radiation patterns for these structures are studied. Both TE and TM polarizations are investigated. Using this hybrid FDTD technique results in a complete and accurate simulation of the total electromagnetic field in the near field as well as in the far field of the grating. It is shown that there are significant differences in the performances of the realistic metal and the perfect metal gratings. © 1995 Optical Society of America.
Kann, JL, Milster, TD, Froehlich, F, Ziolkowski, RW & Judkins, J 1995, 'Numerical analysis of a two-dimensional near-field probe', Ultramicroscopy, vol. 57, no. 2-3, pp. 251-256.
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A hybrid finite-difference-time-domain and angular spectrum technique is used to model near-field optical probe fields and the interaction of the fields with a pyrex substrate. Included in this analysis is a study of the effect of various nanometer sized asperities in the substrate. The hybrid technique provides a straightforward and highly accurate method to simulate the complex electromagnetic problems associated with probe fields. © 1995 Elsevier Science B.V. All rights reserved.
KANN, JL, MILSTER, TD, FROEHLICH, FF, ZIOLKOWSKI, RW & JUDKINS, JB 1995, 'LINEAR BEHAVIOR OF A NEAR-FIELD OPTICAL-SCANNING SYSTEM', JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION, vol. 12, no. 8, pp. 1677-1682.
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Kann, JL, Milster, TD, Froehlich, FF, Ziolkowski, RW & Judkins, JB 1995, 'Near-field optical detection of asperities in dielectric surfaces', Journal of the Optical Society of America A: Optics and Image Science, and Vision, vol. 12, no. 3, pp. 501-512.
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A finite-difference time-domain code is used to model near-zone electromagnetic probe fields of subwavelength dimensions and the interactions of these fields with a dielectric sample. The magnitude and the phase of the electric and the magnetic fields are determined in the region in which the energy leaving the probe interacts with the sample. An angular-spectrum code is then used to propagate the electric field into the far zone, in which signal detection takes place. TE and TM polarizations in a two-dimensional waveguide are modeled. We examine the effects of scanning the probe over a surface asperity in a dielectric sample. Two different far- zone detection schemes (total-energy detection and differential detection with a split-cell detector) are studied. When the probe scans a well, total-energy detection by TE polarization yields the closest estimate of the well’s actual width, whereas differential detection by TM polarization yields the sharpest profile of the well’s edges. Differential detection is shown to be less sensitive to variations in the probe-to-sample separations during a scan and has minimal distortions with both TE and TM polarizations. © 1995 Optical Society of America.
Kot, JS, Nikolic, N, Sainati, RA & Bird, TS 1995, 'Aspects of antenna designs for indoor wireless millimetre-wave systems', Journal of Electrical and Electronics Engineering, Australia, vol. 15, no. 2, pp. 145-150.
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Antenna requirements for an indoor, high data-rate, millimetre-wave wireless local area network system are discussed. Topics considered include the need for shaped antenna beams for efficient cell coverage, resistance to multipath interference, low-cost manufacturing, signal polarisation and physical size constraints. A particular antenna, the ring-slot antenna, being developed as a candidate for this class of applications is described. Results for single ring-slot antennas operating in fundamental and higher order modes are presented. Generation of shaped and electronically scanned beams using an array of ring-slot antennas is described.
Lo, KW & Bird, TS 1995, 'Effect of dielectric coatings on parabolic reflector antenna performance', Microwave and Optical Technology Letters, vol. 8, no. 1, pp. 1-4.
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The effect of a dielectric coating on the gain, co‐polar radiation pattern, and cross‐polarization level of a linearly polarized parabolic reflector antenna is investigated for both dry and wet surface conditions using a physical optics analysis of the equivalent surface currents. By choosing the correct thickness, the effect of a dielectric coating can be minimized, and, at the same time, an equivalent metal‐reflector representation shows that the antenna gain is less sensitive to the coating surface accuracy. Copyright © 1995 Wiley Periodicals, Inc., A Wiley Company
Norros, I, Simonian, A, Veitch, D, Virtamo, J & others 1995, 'A Benes formula for the fractional Brownian storage'.
Piccardi, M, Cinotti, T & Zuffi, S 1995, 'A Preliminary Performance Evaluation Of The Quadrics Architecture With The Darpa Image Understanding Benchmark', High-performance Computing And Networking, vol. 919, pp. 124-129.
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This work presents a preliminary performance evaluation of the Quadrics SIMD massively parallel computer in the execution of a suite of image processing algorithms. The suite is extracted from the low-level and intermediate-level processing sections of t
Shaarawi, AM, Besieris, IM & Ziolkowski, RW 1995, 'The propagating and evanescent field components of localized wave solutions', Optics Communications, vol. 116, no. 1-3, pp. 183-192.
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The diverging and converging components of localized wave solutions are studied within the framework of both the Whittaker and Weyl plane wave expansions. The specific example of the splash pulse is considered because its evanescent components could be derived in an explicit closed form. It is shown that, in the Weyl picture, the evanescent fields associated with the diverging and converging components of the splash pulse cancel each other identically. The splash pulse is, hence, composed solely of backward and forward propagating components of the Whittaker type. © 1995.
Shaarawi, AM, Besieris, IM, Ziolkowski, RW & Sedky, SM 1995, 'Generation of approximate focus-wave-mode pulses from wide-band dynamic gaussian apertures', Journal of the Optical Society of America A: Optics and Image Science, and Vision, vol. 12, no. 9, pp. 1954-1964.
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It is demonstrated that an approximation to the focus-wave-mode field can be generated from a dynamic Gaussian aperture. A source of this type is characterized by the time variation of its effective radius. The performance of such an aperture is studied in detail; it is demonstrated that the dynamic aperture shows a great enhancement over the corresponding static one. The types of source investigated provide an efficient scheme to launch narrow Gaussian pulses from extended apertures. © 1995 Optical Society of America.
SHAARAWI, AM, ZIOLKOWSKI, RW & BESIERIS, IM 1995, 'ON THE EVANESCENT FIELDS AND THE CAUSALITY OF THE FOCUS WAVE MODES', JOURNAL OF MATHEMATICAL PHYSICS, vol. 36, no. 10, pp. 5565-5587.
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Simonian, A & Veitch, D 1995, 'A Bene s formula for the fractional Brownian storage'.
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Ziolkowski, RW 1995, 'Electromagnetic localized waves that counteract Coulomb repulsion to catalyze a collective electron-packet state', Physical Review E, vol. 52, no. 5, pp. 5338-5343.
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The basic generation parameters for a collective electron-packet state that is catalyzed by an electromagnetic localized wave are considered. Cancellation of the large Coulomb forces required to achieve this electron-packet state is shown to be possible with a properly designed electromagnetic field configuration that is intense and applied over an ultrafast time scale. Experimental realization possibilities are discussed. © 1995 The American Physical Society.
ZIOLKOWSKI, RW, ARNOLD, JM & GOGNY, DM 1995, 'ULTRAFAST PULSE INTERACTIONS WITH 2-LEVEL ATOMS', PHYSICAL REVIEW A, vol. 52, no. 4, pp. 3082-3094.
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Bird, TS, Sprey, MA, Greene, KJ & James, GL 1995, 'Circularly polarized x-band feed system with high transmit/receive port isolation', IEE Conference Publication, pp. 322-326.
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Circularly polarized feed system design and performance for an 11 m diameter earth-station antenna, which operates in the frequency band 7.25 to 8.4 GHz, was described. The paramount factor in the design of feed system was requirement of >40 dB isolation at the center of the band. But the feed system has several distinctive features including low-reflection waveguide components and a matched radome on the feed horn enough to achieve high isolation. It has also an insertion loss <0.15 dB, an axial ratio <0.5 dB and a VSWR <1.3 capable to meet the isolation requirement.
Fuente, MP, Guo, YJ, Wilkinson, TA & Barton, SK 1995, 'Direct sequence spread spectrum radio LANs', IEE Colloquium (Digest).
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The performance of direct sequence spread spectrum (DSSS) ISM band Radio Local Area Networks (RLANs) using BPSK modulation and matched filter receivers is investigated. Short and long pseudonoise (PN) spreading sequences, a Barker code and an M- sequence, have been employed in both differential and coherent systems operating in a Rayleigh fading multipath channel with different delay spreads. A channel estimator was designed to perform the system synchronization and control the receiver in order to mitigate the multipath fading and time-dispersion effects by using various multipath diversity techniques. It is found that with low delay spreads the short sequence leads to much better system performance than the long one. It is also shown that use of coherent instead of differential techniques increases the maximum tolerable delay spread.
Gillies, DAG, Johnson, IR, Guo, YJ, Barton, SK & Wilkinson, TA 1995, 'Synchronization techniques for radio LANs', IEE Colloquium (Digest).
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The HIPERLAN system will operate in the 5 GHz and the 17 GHz bands at a data rate of > 23.5 Msymbols. Access to the radio medium is assumed to be asynchronous and the medium to be a Rayleigh fading channel. These would need a robust, synchronization mechanism, so that both timing instants in the receiver can be chosen and equalization performed to mitigate the effects of the time dispersive channel. Results show that the codes perform well under moderately severe channel conditions. An optimum 16 bit sequence was selected for appending to the start of frame synchronization sequence to make up for the full 48 bit training sequence. The added sequence preserves the desired correlation function properties of low sidelobes and zero imaginary part.
Guo, YJ & Barton, SK 1995, 'Flat printed lens and reflector antennas', IEE Conference Publication, pp. 253-256.
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The performance of the printed single and double layer phase correcting arrays is theoretically investigated. The latest development of the single printed reflector is also reported. The effective design of a practical size single printed reflector for the reception of direct broadcasting by satellite is discussed, The reflector encompasses three full Fresnel zones and a quarter wave zone, with a 59.4 cm- diameter and 0.8 focal length to diameter ratio. A 43% optimum antenna efficiency and a bandwidth of greater than 10% are determined. The close-in sidelobes of the antenna are around -22dB and the far-out sidelobes are lower than -30dB.
JUDKINS, JB, HAGGANS, CW & ZIOLKOWSKI, RW 1995, 'FDTD simulation of push-pull tracking servo signals for rewritable optical disks', OPTICAL DATA STORAGE '95, 1995 Topical Meeting on Optical Data Storage, SPIE - INT SOC OPTICAL ENGINEERING, SAN DIEGO, CA, pp. 153-158.
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Liu, RP & Moylan, PJ 1995, 'Dynamic trunk reservation for teletraffic links', GLOBECOM '95 - IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-3, IEEE Global Telecommunications Conference, I E E E, SINGAPORE, SINGAPORE, pp. 432-436.
SAINATI, RA, KOT, JS, NIKOLIC, N & BIRD, TS 1995, 'Printed circuit antennas for indoor millimeter-wave wireless LANs', WIRELESS COMMUNICATIONS, Conference on Wireless Communications, SPIE - INT SOC OPTICAL ENGINEERING, SAN DIEGO, CA, pp. 159-167.
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STAVELEYSMITH, L, WILSON, WE, BIRD, TS, SINCLAIR, MW, EKERS, RD & WEBSTER, RL 1994, 'The Parkes 21cm multibeam receiver', MULTI-FEED SYSTEMS FOR RADIO TELESCOPES, Multi-Feed Systems for Radio Telescopes Workshop, ASTRONOMICAL SOC PACIFIC, TUCSON, AZ, pp. 136-143.