Design of SF6 Gas-Filled Axially Displaced Cassegrain Dual Reflector Antenna with Optimized RF Window Profile for High Power Microwave System

In this study, we propose a high-gain axially displaced Cassegrain (ADC) dual-reflector antenna capable of operating in a gigawatt-level high-power microwave system for neutralizing enemy small UAVs. To optimize the aperture efficiency of the circular reflector antenna, the feed antenna was designed as a dual-mode horn antenna capable of implementing E–/H–plane symmetric radiation patterns. Additionally, an RF window with an optimal thickness was designed by considering the power ratio of each mode to the wavelength in the mode converter of the feed antenna, to provide smooth power transfer at the target frequency. The simulated gain of the optimized ADC dual reflector antenna was 32.52 dBi, achieving an optimum aperture efficiency of 70.7 % and satisfying a reflection coefficient of −30 dB or less. Furthermore, simulation experiments confirmed that the proposed ADC dual-reflector antenna is suitable for use in high-power microwave systems based on the electric field strength between the feed antenna and sub reflector. The performance of the proposed design was experimentally verified, and the measured results generally agreed with the simulated results, except that the gain slightly decreased owing to the fabrication error at the edge of the main reflector. Although the measured gain was lower than the computed expectations, both the reflection coefficients of the feed horn antenna and ADC dual reflector showed good agreement with the simulation. Thus, we verified that the input power can be effectively transmitted through an RF window with an optimized thickness.