The Conversion Gain and Stability of MESFET Gate Mixers

The conversion gain of MESFET gate mixers has been calculated based on the directly measurable S- und Y-parameters, respectively. The analytical results show that parasitic mixing products can be neglected and that the reactions can be suppressed by shorting the IF at the gate and the signal, image, and sum frequency at the drain. The gain which has been measured at a 3.8 GHZ microstrip mixer agrees closely with the one which has been calculated. For a stable and low noise operation it is essential to short all the mixing frequencies except the IF at the drain and the signal at the gate.