Microwave switch circuit and an antenna apparatus.

摘要

A microwave switch circuit includes a first impedance conversion circuit (4a) one end of which is connected to an input/output terminal (1); a resonance circuit connected between the output of the first impedance conversion circuit (4a) and ground, in parallel connection of a field effect transistor (7) and a resonance inductor (8); and a second impedance conversion circuit (4b) connected between the output of the first impedance conversion circuit (4a) and an input terminal (2). A microwave switch circuit may be connected between an antenna side terminal (1) and a transmission wave input terminal (2) and another microwave switch circuit may be connected between the antenna side terminal (1) and a receiving wave output terminal (3). The microwave switch circuit may include the output terminal (3) and the input terminal (2) having an impedance of 50 OMEGA and the output end of the first impedance conversion circuit (4a) having a low impedance lower than 50 OMEGA and the microwave switch circuit may include one-fourth wavelength transmission lines (5) as the first and the second impedance conversion circuits (4a and 4b). Consequently, the maximum allowable value of the incident power is increased and a withstand power is increased in an antenna switch circuit.