# A TM01-TE11 Circular Waveguide Mode Converter on the Basis of Dielectric Filling

## TL;DR

This paper introduces a new circular waveguide mode converter that efficiently converts TM01 to TE11 modes using dielectric filling, achieving high efficiency and wide bandwidth.

## Contribution

The novel use of a coaxial dielectric structure in a circular waveguide significantly improves conversion efficiency and bandwidth compared to traditional methods.

## Key findings

- The mode converter achieves a maximum conversion efficiency of 99.2% when using PTFE as the dielectric material.
- The converter has a bandwidth with conversion efficiency above 90% of nearly 21.1%.
- Experimental results confirm the simulation accuracy and design validity.

## Abstract

In this paper, a dielectric-filled circular waveguide TM01-TE11 mode converter is proposed, which has high conversion efficiency and a wide operating bandwidth. Filling the circular waveguide with dielectric material changes the local propagation characteristics, thus achieving a phase difference between the TE11 modes in the two halves of the circular waveguide during propagation. This, in turn, facilitates the completion of mode conversion with high efficiency. Compared with the conventional radial dielectric plate, this paper improves the method of filling the dielectric inside the circular waveguide by transforming it into a coaxial structure. This is followed by the incorporation of a radial dielectric plate, a modification that has been proven to enhance the conversion efficiency and extend the operational bandwidth. The mode converter operates at 9.7 GHz, and when the dielectric filler material is polytetrafluoroethylene (PTFE), both simulation and practical studies are carried out. The simulation results demonstrate that the maximum conversion efficiency of this mode converter is 99.2%, and the bandwidth with conversion efficiency greater than 90% is nearly 21.1%. The maximum conversion efficiency in the actual test is essentially consistent with the simulation results. The validity of the design scheme of this converter and the accuracy of the simulation study are demonstrated.