Experimental Study on the Frequency Tunability of a Magnetically Insulated Transmission Line Oscillator

In the present study, the frequency tunability of a magnetically insulated transmission line oscillator (MILO) is investigated by simulation in conjunction with an experiment. In the simulation, the tunable MILO reaches a maximum output power of approximately 5.0 GW with an applied voltage of 590 kV and an input power of 29 GW. The corresponding power efficiency is 17.2%, and the frequency is 1.575 GHz. In addition, by adjusting the outer radius of the vane from 77 to 150 mm, the 3-dB tunable frequency of the tunable MILO ranges from 0.85 to 2.12 GHz, and the tuning bandwidth is 85.5%. The experimental results show that when the voltage and current are 405 kV and 42 kA, respectively, the peak microwave power of the tunable MILO is approximately 2.3 GW with a microwave frequency of approximately 1.900 GHz. The difference in the two frequencies at the peak microwave power is significant because of the tuning mechanism. When the outer radius of the vane varies in the range of 76.6–93.0 mm, the 3-dB tunable frequency range is between 1.552 and 2.168 GHz, corresponding to a 3-dB tuning bandwidth of 33.1%. The experimental measurements verify the simulation results.