PORTABLE DIGITAL SATELLITE NEWS GATHERING (SNG) RF TERMINAL USING A FLAT ANTENNA

Error-correction techniques can be used to reduce the required carrier -to-noise ratio (C/N) in digital satellite news gathering (SNG) system s. The required e.i.r.p. of a digital SNG terminal is smaller than tha t of conventional analog SNG RF terminals. In this paper, a Ku-band po rtable SNG RF terminal using a flat antenna is proposed to make the be st 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 distinctl y different from a conventional RF terminal with a parabolic antenna i n two ways; it is portable and it has electronic tracking capability. Electronic antenna tracking reduces the terminal setup time because pr ecise alignment of the antenna with the satellite is not required. Thi s paper first describes the system concept and discusses the design co ncept. Secondly, it then explains phase shifters and feedback loops fo r electronic tracking. The tracking performance of a feedback system u sing four subarrays is also presented with some comparisons between th eoretical 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 exciti ng the rectangular patch antenna, the flat antenna is capable of opera ting dual polarizations and dual frequencies (transmit/vertical polari zation: 14 GHz; receive/horizontal polarization: 12 GHz). The SSPAs ha ve an efficiency of 21% and an output power of 5 W.