Microwave properties of nonlinear MIS and Schottky-barrier microstrip

It is shown that metal-insulatior-semiconductor (MIS) and Schottky-barrier microstrip structures having substrate resistivities within a certain range propagate slow waves with phase velocities that are dependent upon the instantaneous voltage at each point along the line. This and other useful properties of these microstrips can be used advantageously in a number of microwave devices. Loss measurements for the MIS microstrip structure confirm the predictred frequency dependence of the attenuation constant. While the levels of measured attenuation presently achieved are fairly high (4.5 dB/cm at 1 GHz), several methods for reducing the attenuation are proposed. A number of devices are discussed, including an electronically variable phase shifter for which attenuation and phase-shift measurements are presented.