Protection of HF Transmitters from Reflection Failure by Help of Semiconductor Isolators

The fundamental problem of the transmitters protection against microwave energy reflections from aircraft antenna is discussed. The paper presents some applications of active and passive isolators and circulators as a tool for reflections protection. It has been stated that electrical properties of ferrite isolators and circulators grow worse at lower operational frequencies (below 50 MHz) and temperatures (cryogenic). Semiconductor magnetoplasma exhibits gyrotropic effects similar to those of magnetized ferrites and can solve the problem non-reciprocity in the HF range from 3 to 30 MHz, which is important for HF communication. The semiconductor device realization, optimal parameters, and operational temperature range, based on minimum forward loss α and maximum reverse attenuation β, were chosen. Major electromagnetic parameters of semiconductor isolators were determined.