Comparison of degradations in radar system sensitivities due to TR tube and TR limiter

The degradation of radar system sensitivities due to the TR tube and the TR limiter are calculated. A general expression relating to the various parameters of the TR tube and the TR limiter and noise figure of the receiver is derived from the condition that the TR limiter will be more sensitive than the TR tube with keep-alive, KA. In particular, the TR limiter may be less sensitive than the TR tube with KA due to the higher insertion loss of the TR limiter. The much longer life of the TR limiter, however, may be the deciding factor for its use in a radar receiver.