Designing for electromagnetic compatibility in pulsed high power transmitters: a case study

SAMEER has designed and developed a high power S band low noise transmitter for the Doppler weather radar being used by the Indian Meteorology Department at Shar, Sriharikota. The transmitter is capable of delivering 1.2 MW of RF output power. It packages a pulsed high voltage and current of 75 KV and 40 A respectively in the vicinity of low voltage CMOS and TTL logic based control and monitoring circuits. It also has low voltage circuitry floating at 80 KV DC in the vicinity of protective crowbar firing systems. The paper gives a brief case study of the system and the EMC plan followed to overcome the EMI problems faced during the development of the system. The EMI/EMC aspects and the grounding plan of the total system which has been implemented will be presented in detail in the paper.