Electromagnetic Compliance in High Power Communication Satellite Payloads

Abstract

Electromagnetic compliance in communication payloads is an important aspect and integration of the payload components in the spacecraft bus needs to be done in a well planned manner. In a communication payload satellite, poor EMI environment leads to the overall degraded RF performance. Spacecraft carries a very large number of components and accessories and because of high packing density any modification in the final stage is cumbersome and highly time consuming and irritating. EMI control becomes a tedious or even impossible task at the integrated level as it is difficult to pin point the sources and the sinks, which could be large in number. The problems are often observed in transponders at a late stage in integration when it is difficult to analyze and solve. Salvaging actions do not yield the required improvements and are not fruitful. Some important consequences of radiated interference are (a) presence of spurious signals in the output of a subsystem and (b) degradation of the frequency response of a chain of subsystems after integration. An attempt was made to analyze and quantify the effect of EMI feedback on the frequency response, so that the EMI behavior of subsystems could be co-related with overall gain ripple. An ‘Electromagnetic Compliance Plan’ for Communication Satellite payloads was evolved and implemented successfully with quite satisfactory results.