L-band high power electronically rotatable ferrite half-wave plate

Rotatable ferrite half-wave plates allow efficient selection of any desired amount of reciprocal vector rotation when excited by a linearly polarized wave, or any desired amount of reciprocal phase change with circularly polarized excitation. Ability to handle high peak power levels requires careful selection of the ferrite material properties, and high average power handling can be promoted by incorporating heat sinking into the structure. This paper describes the design approach and characteristics of an air-cooled ferrite half-wave plate operating in the vicinity of 1.3 GHz. frequency at a peak power level of 65 kW. and an average power level of 6,500 W. Measured data are presented for an engineering model unit with 0.4 dB. maximum insertion loss, capable of switching between any two states in approximately 500 microseconds.