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Portable Digital Satellite News Gathering (SNG) RF Terminal Using a Flat Antenna
Takao MURATA Hideo MITSUMOTO Masaru FUJITA Shoji TANAKA Kouichi TAKANO Kazuo IMAI Noboru TOYAMA
IEICE TRANSACTIONS on Communications
Publication Date: 1994/12/25
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Digital Broadcasting Technology)
satellite communication, digital SNG, SNG RF terminal, flat antenna, SSPA,
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Error-correction techniques can be used to reduce the required carrier-to-noise ratio (C/N) in digital satellite news gathering (SNG) systems. The required e.i.r.p. of a digital SNG terminal is smaller than that of conventional analog SNG RF terminals. In this paper, a Ku-band portable SNG RF terminal using a flat antenna is proposed to make the best use of these digital systems. This portable terminal uses 16 planar microstrip subarray antennas, each with a solid-state power amplifier (SSPA) mounted on its backside. The proposed RF terminal is distinctly different from a conventional RF terminal with a parabolic antenna in two ways; it is portable and it has electronic tracking capability. Electronic antenna tracking reduces the terminal setup time because precise alignment of the antenna with the satellite is not required. This paper first describes the system concept and discusses the design concept. Secondly, it then explains phase shifters and feedback loops for electronic tracking. The tracking performance of a feedback system using four subarrays is also presented with some comparisons between theoretical and measured results. Experimental results for the low side-lobe flat antenna and the SSPAs are then presented. These are the most important components of the system. The flat antenna meets the design objectives specified by ITU-R Recommendations. By orthogonally exciting the rectangular patch antenna, the flat antenna is capable of operating dual polarizations and dual frequencies (transmit/vertical polarization: 14GHz; receive/horizontal polarization: 12GHz). The SSPAs have an efficiency of 21% and an output power of 5W.