Compact dual-band rectangular TE10 mode to circular TM01 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 waveguide TE<inf>10</inf> mode to circular waveguide TM<inf>01</inf> 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 TM<inf>01</inf> 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 TM<inf>01</inf> 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 addition 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<inf>01</inf> mode and suppression levels of circular TE<inf>11</inf> 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<inf>11</inf> mode and less than 0.6 dB insertion loss of TM<inf>01</inf> mode within 500 MHz bandwidth at TX band it gives more than 23 dB return loss and suppression of TE<inf>11</inf> mode and less than 0.3 dB insertion loss of TM<inf>01</inf> mode within 900 MHz bandwidth at RX band. © 2023 Elsevier B.V. All rights reserved.