Intermodulation performance of solid-state UHF class-C power amplifiers

The subject of this paper is the use of Fourier-Bessel series expansion models in the prediction of the intermodulation performance of both traveling-wave-tube (TWT) amplifiers and solid-state class-C UHF amplifiers. Theoretical and experimental results are described and compared. It is shown that in the case of the solid-state amplifiers, a dynamic-characteristic measurement technique must be used before reliable predictions can be achieved. A simple intermodulation-noise reduction scheme is described for use with high-power efficient class-C solid-state amplifiers. It is demonstrated that a carrier-to-intermodulation noise power ratio improvement of 10 dB can be achieved with a minimal decrease in prime-power efficiency.