Trade-off between intermodulations and thermal noise in a satellite transistor power amplifier

When a non-linear power amplifier is operated with a multicarrier signal, intermodulation products are produced and the link is impaired. In order to quantify this impairment two questions have to be resolved; first whether the IM spectra produced by the modulated carriers have any residual subjective effect and second, what is the equivalent noise level to be added to the thermal noise in the link budgets. This paper describes the experimental work done in ESTEC in order to answer the above questions.