A millimeter-wave high power combining circuit based on a waveguide-based lossless symmetric 180° 3-dB hybrid

This paper presents a millimeter-wave broadband high power combining scheme with a waveguide-based lossless symmetric 180deg 3-dB hybrid, in which completely match and isolation cannot be obtained simultaneously. And then with millimeter-wave high power MMIC PAs(TGA4517-EPU) integrated, a two-way high power combining circuit is fabricated. The CW output power measured is more than 35.8 dBm in 31- 35 GHz, and the maximal output power, 37.5 dBm is observed at 32 GHz. The corresponding combining efficiency is more than 78% in the working bandwidth of the devices adopted. This new millimeter-wave waveguide-based solid-state high power combining scheme has properties of compact structure, easy fabrication process, good heat sinking and high combining efficiency in a broad bandwidth, and has potential for millimeter-wave broad-band high power combination.