Radiation patterns of a mode transducing antenna

Radiation patterns for the general case of
TE_{0n}
excitation of Wengenroth's mode transducing antenna are derived. The antenna seems well suited for application as a launcher for electron cyclotron resonance heating (ECRH) plasma heating. Gain and launching efficiency are calculated. Very good agreement is found between predictions and experimental results for
TE_{01}
mode excitation.