Design and experiment research on an oversize mode-transducing antenna

Under the circumstance of oversize coaxial waveguide, the traditional coaxial mode converter with four metal plates inserted does not satisfy the unique-mode requirement. In this paper, an oversize mode converter is designed with eight metal plates inserted. Moreover, it combines with a coaxial horn to form a mode-transducing antenna, which can directly radiate coaxial TEM mode from high-power microwave sources. The center frequency is 7 GHz. The calculated results of the antenna are as follows: the antenna gain is 22.2 dB with an aperture efficiency of 53.7%, the reflection coefficient is 0.07 at the center frequency and less than 0.3 in the range of 6.5~7.5 GHz. The measured results are as follows: the antenna gain is 21.5 dB with an aperture efficiency of about 46%, the reflection coeff