Mixer diodes for 6 gigacycles per second

Microwave communication systems use the nonlinear resistance property of semiconductor diodes for down frequency conversion in superheterodyne circuits and either the nonlinear resistance or capacitance property for subsequent conversion to the original or to a new microwave frequency. Target specifications are discussed for a low-level down convertor diode and one used for medium level up-conversion. Conversion loss and noise temperature ratio are significant parameters, and these are discussed together with radio and intermediate frequency impedance, and burnout level. Germanium diodes are preferred to silicon or gallium arsenide, and an aluminium bronze whisker is used. Details of construction and performance are given. The down-convertor diode has an intermediate frequency impedance of about 200 ohms, and the envelope or, amplitude limiting characteristic of the up-convertor using the nonlinear resistance action can be controlled by choice of semiconductor resistivity.