技術情報とプレゼンテーション

The high-power microwave sources generate waves with the output mode of TM01 mode which has null at the boresight upon radiation. The output mode of the source is transformed to some other mode having a maximum field pattern at the boresight such as TE11 mode. In this work, a compact, linear, and efficient mode converter design is presented. The mode conversion of TM01 to TE11 mode is achieved by using a step waveguide transformer. The mode converter is designed using COMSOL multiphysics for the operating frequency of 3 GHz. The design phase involved modeling a mode converter using theoretical calculation, determining its length parameters, and minimal optimization to achieve a mode conversion of more than 90% with a good bandwidth. The mode converter is fed by TM01 mode using a TM01 launcher and the output mode TE11 is detected by the TE11 detector. Simulation and measurement result shows mode conversion efficiency of 95%, return loss of less than 20 dB, and bandwidth of 70 MHz. The performance of the mode converter is assured by connecting the mode converter with a horn antenna and observing the radiation pattern. The radiation pattern verifies the mode conversion with maximum E field pattern at boresight and return loss of 20 dB.