Millimetre wave semiconductor based isolators and circulators

Abstract

This paper illustrates the use of gyroelectric behaviour of magnetically biased semiconductors in designing non-reciprocal components, namely isolators and circulators, working in the millimetre wave frequency range. Two types of isolators are proposed to work in the V band (50-75 GHz) designed by inserting an Indium Antimonide (InSb) at liquid nitrogen temperature inside a rectangular waveguide. More than 30 dB differential isolation was obtained in both designs by transversely biasing the InSb slabs with magnetic field of 0.5 T. In addition, different types of Semiconductor Junction Circulators (SJC's) working in higher frequency ranges are illustrated. Theoretical analysis and electromagnetic simulation show that circulation is possible at frequencies up to 650 GHz using InSb cooled down to 77 K. It is also shown that non-reciprocal behaviour for circulators is possible by exploiting the high mobility Two Dimensional Electron Gas (2-DEG) layers in heterostructures. Despite the low temperature operation required for these components, these designs can be regarded as promising candidates for currently unavailable non-reciprocal components in millimetre-wave and THz frequency ranges.