Millimeter-wave Spatial Power Combining Technology Research

High-power amplifiers are a necessary component of wireless transmitters at microwave and millimeter-wave frequencies. Especially at millimeter-wave frequencies, power available from each monolithic microwave integrated circuit (MMIC) is limited, and subsequent power combining is required to achieve the desired output power. High-power amplifiers with broad bandwidth are essential for this purpose.In this thesis, various wavegudie-based millimiter-wave power combiner structures have been studies and analyzed. The structure combined by the branched-waveguide coupler and waveguide-to-microstrip double probes is used as a power divider/combiner to research the technology of millimeter-wave power combiner. This thesis has discussed complication which can affect the combining efficiency, and it researches four ways of spatial combination structure. By deeply researching waveguide-T-junction, branched-waveguide coupler which researched by using even-old modes thory and waveguide-to-microstrip double probes in Ka band, which are simulated and optimized respectively. After a comparative analysis, this structure is more suitable as a power combiner. The simulated and measured results of this power divider/combiner demonstrate the advantages of simple structure, broadband, low insertion loss, sufficient heat sinking for the active devices, uniform phase responses and power of output ports, and better stability.At last, the power combiner combined by the branched-waveguide coupler and waveguide-to-microstrip double probes has been assembled at Ka band. Based on the researching and experimenting, the Ka band high-power amplifier can provide output power more than 23W, the small signal gain is more than 50dB and the combining efficiency is over 80% in the 29.4-31GHz. And the highest combining efficiency is 95.8% at 30GHz. This structure is assembled in V band for the first time. The V band power amplifier can provide output power more than 200mW in the 55-61GHz, the small signal gain is more than 30dB and its combining efficiency is estimated to be 85%.