Quasi-optical techniques for MM-wave heterodyne systems

This paper is a review of some of the quasi-optical techniques that have been used in the design and development of heterodyne systems at St. Andrews University. In the first section a brief introduction to quasi-optics is given, including free-space isolation. Measurement techniques are then reviewed which are useful in the development of heterodyne systems including impedance and oscillator noise measurements. A number of different examples of the use of quasi-optics in heterodyne systems are then presented including cavity stabilisation techniques to improve the FM noise on oscillators, universal polarisation manipulation, single side-band filters, notch filters, spatial filters and a dual polarisation 94 GHz radar system