Design and measurement of a 3.7 GHz high power recombiner

Abstract The design and measurement of a high power recombiner at 3.7 GHz for the lower hybrid current drive (LHCD) system on HL-2A tokamak is presented. It consists of two rectangular waveguides with the shared height wall removed. This combiner is analyzed and calculated based on the Eigen modes in rectangle waveguide and the transmission line theory preliminarily. Simulation and optimization is performed by finite element method. The measured results agree with the simulated ones within the error range. The power combining efficiency reaches 98.1% and is extended when the input power is not balanced.