Some Aspects of Mixer Crystal Performance

A method for calculating the conversion loss and conductances of a crystal mixer is presented. The magnitude of the dependence of these characteristics on terminations at the image frequency and at the sum frequency is shown. Experimental verification of the calculations is shown by measurements and by reference to the literature. An investigation of crystal noise characteristics is reported, and it is shown that there is an optimum intermediate frequency for minimum noise figure. The design criteria for minimum receiver noise figure are shown.