Spatial power combining of Ka-band microfabricated TWTs based on a planar helix slow-wave structure

Spatial power combining of two Ka-band microfabricated traveling wave tubes (TWTs) is reported. The TWTs are based on planar helix slow-wave structure with straight-edge connections (PH-SEC). Transition from a waveguide to the PH-SEC forms the basis for division of input power from a waveguide to the TWTs and for combining the output power into a waveguide. For a 3.7 KV and 10 mA beam, the PIC simulation results show that the output power can reach 13 W at 30GHz, with a calculated combining efficiency of 98%.