Simulation Study of Radiation System for L-band Magnetically Insulated Line Oscillator

A magnetically insulated line oscillator is a narrow band cross-field device that combines the technologies of slow wave structure and self-insulating magnetic field, resulting in its giga-watt operation without electric breakdown. This paper presents a simulation study of an L-band MILO with reflectors and a mode-transducing antenna. MILO is simulated using CST with the particle-in-cell method. Simulation results show that a 1.82 GHz high power microwave of dominant output TEM mode with peak power of 9.1 GW and peak power efficiency of 22% is generated when diode voltage of 680 kV and beam current of 60kA is applied at the input. While in conventional MILO, the peak output power is 7.6 GW so the reflector configuration resulted in a 20% efficiency increase. To get maximum power at boresight as well as good radiation symmetry pattern and low sidelobes level, a radiation system based on TEM-TE11 plate inserted mode converter and Gaussian profile conical horn antenna is designed and simulated for MILO with reflectors. The conversion efficiency of the mode converter is 98.5% at 1.82 GHz and over the frequency range of 1.65-1.9 GHz, it is above 90%. The antenna has a gain of 18.8 dBi at 1.82 GHz and VSWR less than 1.5 dB over the operating frequency range. Both the E-plane and H-plane, have 3-dB beamwidth of 21.6° and 21.2° respectively, and sidelobes level less than -36 dB.