Folded Waveguide: a New Kind of Radio-Frequency Antenna

The properties of folded waveguide (FWG) couplers are researched. Firstly, the electromagnetic fields inside and outside of the FWG are analyzed theoretically. After substituting the relevant data, numerical results and corresponding two-dimensional and three-dimensional wave field figures are achieved. Secondly, in our scale model, series of experiments are carried out. The coupling and matching between the antenna and the coaxial line are examined. The experimental results demonstrate that FWG antenna can be used in ion cyclotron range of frequencies heating in tokamak with high power coupling efficiency.