Effects of noise contributed by t.r. devices on low-noise receivers

The deleterious effects on the noise factor of a receiving system of inserting a t.r. device immediately before a quiet microwave amplifier are investigated. The noise contribution of the device is separated into its component parts, each of which is examined of its contribution to the degradation of the receivingsystem noise factor. In addition, the noise factor of the t.r. device is determined, independent of interconnecting components. A technique to measure excess noise energy is presented, from both an analytical and practical viewpoint. It is shown that an independent determination of noise factor, and relative gains of signal and image frequencies of the test receiver, are not necessary when measuring igniter noise ratio.