Power Capacity of HF Automatic Antenna Tuner Switched by PIN Diodes under Load Mismatch Conditions

Digital forms of communication with error-correcting coding and automatic change of operating frequencies have made it possible to simplify HF radio communication. At the same time, the problem of automatic antenna matching in a wide frequency range has become more actual. PIN diodes are widely used in radio transmitting and receiving devices from high frequencies to microwaves. With their help, attenuators, phase shifters and two-way switches may be implemented. The use of PIN diodes, which are switching elements of the microwave range, in the high-frequency range imposes certain restrictions both on the magnitude of the maximum switched current and on the amplitude of the control signals. An analysis of the achievable power values of HF automatic antenna tuning unit (ATU) switched using by PIN diodes showed that in the case of a matched load, they can be used up to power levels almost equal to 2 kW in the HF range. With a strong antenna mismatch, the maximum power levels are reduced to 170 W when operating at frequencies above 3 MHz and to 100 W when operating at frequencies above 1 MHz.