Broadband radial waveguide power amplifier using a spatial power combining technique

A broadband radial waveguide power amplifier has been designed and fabricated using a spatial power dividing/combining technique. A simple electromagnetic model of this power-dividing/combining structure has been developed. Analysis based on equivalent circuits gives the design formula for perfect power-dividing/combining circuits. The measured small-signal gain of the eight-device power amplifier is 12-16.5 dB over a broadband from 7 to 15 GHz. The measured maximum output power at 1-dB compression is 28.6 dBm at 10 GHz, with a power-combining efficiency of about 91-. Furthermore, the performance degradation of this power amplifier because of device failures has also been measured.