Base-station tracking in mobile communications benefits from a directional antenna and so requires direction finding technology. A novel technique for electronically directing the radiation pattern of an antenna array employs a directional array with only one active element and three parasitic elements operating near resonance. Three different methods of direction finding are assessed; a coarse angular location method, a precise angular location method assuming one incident beam, and a precise angular location method with multiple incident beams. An array with n elements, if used in conjunction with a relatively simple controller, can be used to resolve n 0 1 signals. This technology can be implemented using both wire and patch antenna-array elements and either linear or circular polarization can be used, lending the technology to applications in both terrestrial and satellite communications systems.
Current methods of electronically controlling the radiation pattern of an antenna system include the use of servo-motors and phase switched active elements. The servo-motor system is slow, power intensive, requires regular maintenance and also is physically
This presentation describes a four microstrip Yagi-Uda antenna array. The single microstrip Yagi-Uda antenna was developed by J. Huang at Jet Propulsion Laboratory, and had a maxirnurn gain of 8dBic (J. Huang; "Planar Microstrip Yagi Array Antenna", IEEE AP-S Symposium Digest June 1989, pp 894-897).A single Yagi-Uda antenna consists of a single driven patch, a larger reflector patch and two smaller director patches. This mangernent shows many advantages over a single microstrip patch antenna, which include a slightly increased forward
This paper presents the results of investigations on three types of high frequency transformers with different magnetic and winding configurations €or the switching resonant mode power supply. The experimental results demonstrate the characteristics of self inductance and voltage ratio versus frequency. The magnetic flux and eddycurrent distributions of Pot core, Planar core and Multi-element core transformers are calculated by a CAD/CAE software package eh employs boundary element method technique. Both experimental and computer modelling results are used for optimum design of high frequency transformers and minimising the copper losses in transformer windings.
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