A Single-Balanced Diode Mixer, using a microstrip line and two schottky barrier beam lead mixer diodes, is designed and implemented.
The impedence matching to the pumped diode at RF and IF frequencies are achieved by two steps. At first, The equivalent circuit values of the diode are empirically taken as $R_s$ = 3Ω, $R_j$=70Ω, $C_j$ = 65fF at RF and only $R_j$=100Ω at IF. Then, impedence matching circuit using microstrip line is designed by the computer simulation. At second, Stubs using conductive tape are added on the microstrip line, which reduces conversion loss.
The implemented mixer operating at 35.0GHz~35.05GHz in RF, LO frequency have roughly 6.5dB conversion loss, 32dB RF/LO Isolation, 37dB IF/LO Isolation, 7.5dBm 1dB compression point, 30dB IF 2nd hormonics suppression, 40dB IF 3rd harmonics suppression, and 2.17 IF SWR.
