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 theor etically. After substituting the relevant data, numerical results and corre sponding two-dimensional and three-dimensional wave field figures are achie ved. Secondly, in our scale model, series of experiments are carried out. T he coupling and matching between the antenna and the coaxial line are exami ned. The experimental results demonstrate that FWG antenna can be used in i on cyclotron range of frequencies heating in tokamak with high power coupli ng efficiency.