A Low Standing-Wave-Ratio Wideband Mode-Transducing Antenna for High Power Microwaves

A novel $L$ -band wideband coaxial mode-transducing antenna, which converts the coaxial TEM mode into circular TM 01 mode, is realized and tested in this article. The mode-transducing antenna is composed of a coaxial wideband multiple-reflection mode converter with the three groups of supporting rods and a compact coaxial conical horn with a dielectric lens. First, the schematic and operating principle of the mode-transducing antenna are analyzed theoretically. Then, the structure design and optimization with simulated results are performed for demonstration. Finally, a prototype of the mode-transducing antenna is fabricated, measured, and verified in terms of reflection characteristics, radiation patterns, and far-field waveforms. The measured results reveal that the mode-transducing antenna achieves the bandwidth wider than 31% with the transmission efficiency higher than 98.2%. The high-power test with the magnetically insulated transmission-line oscillator (MILO) show that the power handing capacity of the mode-transducing antenna is greater than 4.0 gigawatts (GW). The measured results are in good agreement with the simulated results. Therefore, the mode-transducing antenna has a good application prospect in the field of high-power microwave (HPM).