Study of Dual-Frequency Polarizer for Electron Cyclotron Resonance Heating Systems of 105 and 140 GHz

In electron cyclotron resonance heating (ECRH) systems, the desired polarization is achieved by using two polarizers, a linear polarizer and an elliptical polarizer. These two polarizers serve as an important part of a 63.5-mm corrugated metallic waveguide transmission line for the ECRH. The dual-frequency polarizers (DPs) for the 105- and 140-GHz systems were designed in the present article by using the optimization of the phase difference method. The linear polarizer of 105-GHz shared an optimized polarizer with an elliptical polarizer of 140 GHz. The elliptical polarizer of 105-GHz shared another optimized polarizer with a linear polarizer of 140 GHz. The polarization characteristics of the single-frequency and DPs at the frequencies of 105 and 140 GHz were analyzed and compared. The polarization purity of the combination of the two polarizers was also calculated. The results indicated that arbitrary polarization state could be successfully achieved with the use of the designed DPs.