Wide-band HE11 mode terahertz wave windows for gyro-amplifiers

Broadband HE11 mode output windows, based on the multilayer concept, are studied for high power gyro-amplifiers operating in the low terahertz region. As the wave power in the hybrid HE11 mode is concentrated in the center of the circular waveguide, smaller reflection and better coupling to the fundamental free space Gaussian mode can be achieved for the windows. Two windows are designed for optimized performance through simulations for operation in two frequency ranges of 360– 400 GHz and 90–100 GHz. The simulated performance, practical constraints in realization and manufacturing methods of the 90–100 GHz window is discussed. This window was constructed and microwave properties measured showing a lower than -27 dB reflection. This result agrees with simulation data which validates the simulation methodology and effectiveness of the design.