This paper describes the development of 100kW medium-wave radio transmitter with SITs. In designing this new transmitter, countermeasures against the reflected power impressed on the transmitter with the antenna base shorted, power variation in the load change and others are taken to obtain an output power of 100kW with high stability. The transmitter is composed of two 50kW transmitters in parallel and one stand-by 50kW transmitter. Each transmitter consists of six 10kW transmitters with two 5kW power amplifiers and one l0kW modulator.
The measuring system designed and constructed by authors performs automatic multiple frequency measurements of antenna radiation patterns in a short time during a single rotation of the test antenna by sweeping quickly over the test frequency range every required angle of antenna position. The experimental results of these radiation patterns are compared with the theoretical results calculated by moment methods for TV receiving antennas.
An improved strip element and an improved feed-network for CP-PASS (Circularly Polarized Printed Antenna composed of Strip dipoles and Slots ) are presented. The improved feed-network is formed into an H-shape to realize a wider axial ratio bandwidth. The improved strip element is placed in the ground plane to reduce the necessity to correct the element length after placing a reflector. A 48 element-set CP-PASS with sufficient gain has been realized as a subarray of a planar antenna for DBS reception.