A Ka-Band Broadband Radial Power Combiner With High Isolation Among All Input Ports

This work presents a broadband isolated Ka-band radial space power combiner based on TE₀₁ mode in a circular waveguide. The combiner consists of two parts: an isolated 24-way radial power combiner and a broadband circular waveguide TE₀₁-mode transducer. A kind of approximate half-height waveguide absorbers are embedded at the circular bottom of the radial power combiner for the first time, which significantly increases the input port’s return loss (RL) and isolation among input ports while also improving the size tolerance of the absorber and lowering installation difficulty. After employing the absorbers, the measured results of minimum isolation of 16 dB among input ports, the average RL improvement of 13 dB at the input ports, the minimum RL of 14 dB at the output port, the maximum insert loss of 0.75 dB, and the lowest passive combining efficiency of 84% are realized within 26–42 GHz with a relative operating bandwidth of 47%. Additionally, the analysis of power-handling capability and the high-power tests under a continuous wave power of 300 W were carried out. To the best of our knowledge, this is the widest operational bandwidth power combiner based on the circular waveguide.