Waveguide power combiner with adjustable amplitude and phase response

Maximum gain from combining multiple high-power signals is achieved by equalising both the amplitude and phase of the combination. Achieving in-phase and equal amplitude power combining with amplifiers of unequal gain and group delay requires compensation by means of delay lines and external gain adjustment. This paper proposes an improved X-band waveguide H-plane cross-guide combiner which allows for post-production adjustment of the combining power ratio, as well as equalization of the phase responses. This adjustment capability allows for mass-production of the combiner, irrespective of the exact phase and gain characteristics of individual amplifiers. The nominally equal amplitude combining ratio is shown to be adjustable by ±0.4 dB over 400 MHz bandwidth at X-band, whilst the phase difference may be altered, independently from the amplitude response, from -2.52° to +2.52°. Good agreement is found between simulated and measured results.