Reflective predistortion linearizer for Ka-band travelling wave tube amplifiers

The power series method is used to analyze the nonlinear distortion characteristics of the predistortion linearizer which are contrary to the distortion characteristics of the travelling wave tube amplifier(TWTA), and also the model of the predistortion linearizer is proposed. As anti-parallel Schottky diodes can produce odd-order harmonics, a reflective predistortion linearizer for Ka-band TWTA is designed using the structures of anti-parallel schottky diodes, quadrature hybrid bridges and matching networks. The result of experiment shows that 19 dB improvement is introduced to the carrier-to-intermodulation ratio of the TWTA which reaches and even exceeds the demand.