Compact dual-band rectangular T E10 mode to circular T M01 mode converter for telemetry/telecommand applications in satellite communication: design equivalent circuit modeling mode level measurement technique and 3d printed manufacturing

Abstract

In this study the design of a dual-band mode converter which provides transition from rectangular waveg- uide $TE_{10}$ mode to circular waveguide $TM_{01}$ mode and operates simultaneously in telemetry/telecommand (TT&C) frequencies is presented along with its equivalent circuit and a mode level measurement technique. This dual-band converter is designed to uniformly excite TT&C slot antennas used in satellite communication with symmetric circular T M01 mode. The structure can work as a transceiver due to having one common rectangular waveguide feed. As a Ku-band application a converter giving high purity T M01 mode at circular waveguide at 11.75 GHz/TX and 13.75 GHz/RX center frequencies is designed and manufactured with 3D printing technology. Approximate equivalent circuit models of the designed structure are extracted by using lumped elements from simulated S-parameter results. In addi- tion a measurement technique to detect the normalized power levels of different propagation modes in dual-band mode converter is applied on the manufactured structures to obtain transmission levels of circular $TM_{01}$ mode and suppression levels of circular $TE_{11}$ mode. It is revealed from the measurement results that while the designed structure gives more than 17.5 dB return loss and suppression of $TE_{11}$ mode and less than 0.6 dB insertion loss of $TM_{01}$ mode within 500 MHz bandwidth at TX band it gives more than 23 dB return loss and suppression of $TE_{11}$ mode and less than 0.3 dB insertion loss of $TM_{01}$ mode within 900 MHz bandwidth at RX band.