An Improved TEM-TE11 Mode-Transducing Sectoral Antenna Using Dual Dielectric Window

Most of microwave sources, such as electromagnetic tubes, generate circular TEM or circular TM01 mode. The best radiating mode of cylindrical waveguides is circular TE11 mode. Therefore, mode transducers are used to convert circular TEM or circular TM01 to circular TE11 mode. In this paper, designing and fabricating of a mode transducer that convert circular TEM to circular TE11 mode are investigated. The combination of this mode transducer with an open-ended waveguide antenna makes it sutible for compact usages. The mode transduser antenna is designed to handle high power and therefore its internal area is closed by the help of a dielectric window to become vacuum. Mode conversion is carried out by changing the phase velocity of each mode-transducing section. The maximum achieved gain of this antenna is 8.8 dB in 1.48 GHz frequency. An optimized dual dielectric window at the end of the waveguide improves the antenna matching. The measured results are in a good agreement with simulation results.