High-efficiency millimetre-wave spatial power combining structure

A high-efficiency millimetre-wave spatial power combining structure that is a waveguide power combining network is proposed. High phase and amplitude consistency and isolation between the output ports are the key factors for the high-efficiency power combining structure. The phase and amplitude consistency is guaranteed by the symmetry of this structure. As a sample, an eight-way power splitting and combining network in the Ka-band is designed, fabricated and measured. In a fractional bandwidth of 20% around a centre frequency of 33 GHz, the measured results show that the phase and amplitude differences between the output ports are smaller than ±1.5° and ±0.1 dB, isolation between the output ports is higher than 17 dB, insertion loss is lower than 0.1 dB, and the return loss of the input and output ports is better than 18 dB. The proposed broadband eight-way power combining network can improve the spatial power combining efficiency to a great extent with excellent performance.