Experiment of Frequency Range Dependent TE10 to TE20 Mode Converter

Typical metallic waveguide mode converters convert electromagnetic waves from one mode to another mode for some frequency ranges. However, most electromagnetic waves outside of the specified frequency range are reflected. We report a design for a mode converter which passes the TE10 mode at a low frequency range and efficiently converts the TE10 mode to the TE20 mode at a high frequency range. To gradually shift the mode profile from TE10 to TE20, dielectric rods are placed in a sequence along the waveguide starting near the sidewall and moving to the center of the waveguide with decreasing radius of the rods. This design reduces reflection of electromagnetic waves. Experimental tests demonstrate the efficacy of the design.