Design of a 3.7 GHz, 1 kW CW hybrid radial power divider for LHCD system of SST-1 Tokamak

Abstract

This paper presents a novel design of an 8-way radial power divider/combiner that exhibits low insertion loss and minimum phase imbalance. The proposed design is realized using combined features of resonant and non-resonant based power dividing/combining structures to reap the benefits of both kinds of designs. The multi-layered power divider is designed to operate at a frequency of 3.7 GHz for possible use in Lower Hybrid systems for fusion applications. The structure is simulated using COMSOL Multiphysics to evaluate its RF and thermal performance. Simulation results indicate that the proposed power divider exhibited an amplitude and phase imbalance of ±0.05 dB and ±0.1° respectively between the peripheral ports. The computed return loss for the input port of the power divider is around 56 dB while the insertion loss is approximately 0.24 dB. Coupled RF-thermal simulation results indicate the capability of this design to handle continuous wave (CW) power of up to 1 kW. The proposed device is intended to be narrowband and would be used in the 1 kW solid state RF source under development at the authors’ institute.