THz broadband quasi-optical mode converter antenna system

摘要

This paper presents a broadband quasi-optical (QO) mode converter antenna system, which can transfer a waveguide TE62 mode into free-space Gaussian beam around 330 GHz. The converter contains a Vlasov launcher and three reflector mirrors. Special considerations, including a reasonably large aperture of the Vlasov launcher and the optimized combination of two elliptic reflectors and a bifocal parabolic reflector, are the keys to achieve broadband mode converting. The optimized converter is well compatible with the gyrotron electron-optical system and generates Gaussian beam with efficiency higher than 80% in a broadband range between 310-340 GHz. The principle of the broadband converter can also be applied to gyrotron amplifiers, even other gyrotron devices.