Smoothly profiled quasi-optical output launcher for a W-band gyro-TWA

A W-band quasi-optical horn with smoothly profiled circular inner surface was optimized and measured for a gyrotron traveling wave amplifier. It was designed to achieve low reflection, high fundamental Gaussian mode content and high directivity in the desired frequency range of 90 to 100 GHz. In the measurement, the reflection of the TE
₁₁
mode was lower than -37 dB and the directivity was ~27 dB with side lobes better than -30 dB.