Amplitude stabilisation and multi-channel isolation

The generator or source model which is implicit in Chapter 3 eqn. 3.10 may in reality be a poor representation of a given source of microwave energy. On the other hand, with appropriate techniques, it is possible, in principle at least, to achieve any desired degree of conformity to the postulated model. In general there are two problems: frequency instability and amplitude instability. In its simplest form, frequency instability may be corrected by sampling the signal of interest, comparing its frequency against some reference and the introduction of appropriate feedback as required to achieve the desired result. This chapter will attempt to develop an understanding of amplitude stabilisation and consider some related topics.