A Measurement Technique For Determination of Power Levels of Different Propagation Modes in Circular Waveguides

Abstract

This study describes a measurement technique for detecting the power levels of different propagation modes in a circular waveguide in the mod converter structure from a rectangular waveguide to a circular waveguide. Specially designed SMA-waveguide adapters are generally used to measure these power levels of propagating modes inside the circular waveguide. While these adaptors can measure power level of desired transmitted mode they are inadequate to obtain suppression levels of other propagation modes simultaneously. Without need of special adapters the technique proposed in this study can determine the amplitudes of different propagation modes in the waveguide at the same time by using 2-port S-parameter values belonging to two identical mode converters. This method has been verified by a rectangular TE10 - circular TM01 mod converter designed and manufactured at center frequency of about 11.4 GHz.