Millimetric Low Noise Preamp-Mixers for Application with Circular Waveguide Transmission Systems

Preamp-mixer specifications are defined by system considerations. Technological developments are described for realization of low noise millimetric mixers using chip Schottky diodes in honeycomb structure. Similar diodes can be used either in microstrip or wave-guide technology. A two stage preamplifier is computed and realized. Output preamplifier includes a wideband lumped circulator. The interconnection between mixer output and preamplifier input achieves a good matching for minimum noise figure. This quadripole can be adjusted in order to permit a possible exchange of mixer diode without damaging the general preamp-mixer characteristics.