Millimeter-wave Spatial Power Combining Technology Research

Spatial power combining technique provides a viable solution to the realization of solid-state power sources and amplifiers at millimeter-wave frequencies. As a new type of spatial power combining technique, the waveguide-based spatial power combining technique will become a hot research topic from its successful demonstrations. The basic theory and structure of millimeter-wave waveguide-based spatial power combiner was analyzed and a solution of Ka-band standard waveguide-based spatial amplifier was presented.A Ka-band two-way waveguide-to-microstrip transition, using a finline array for waveguide mode termination and then transferring the energy to microstrip with a broadband finline-to-microstrip transition, is designed. This optimized two-way combining structure showed a very low back-to-back Insertion Loss of 0.3dB and Return Loss better than 15dB over all Ka-band, especially 0.1dB and 20dB over the frequency range of 28GHz-36GHz. The two-way(1×2) power combining approach was extended to four-way(2×2) power combining by vertical stacking inside the waveguide. This 2×2 power combiner showed the maximum potential combing efficiency of 95%. The gold-wires connection between microstrip and MMIC was simulated in order to save the time when bonding practically. Then a satisfied performances of Ka-band solid-state spatial power amplifier was realized by means of ADS.