Wavenumber: An Alternative to the Directional Coupler for Multimode Analysis in Oversized Waveguides

摘要

The problem of measuring a broad spectrum of discrete modes in oversized waveguides is discussed. Analysis of the standard solution, the directional coupler, shows that the measured signals can be ambiguous in mode selectivity and directivity. Therefore an instrument, the wavenumber spectrometer, which avoids the problem of ambiguity was developed. The instrument has extremly high directivity and allows the measurement of all TE and TM modes with the same instrument. The device inherently has a large frequency bandwidth. This wavenumber spectrometer consists of a leaky-wave antenna structure in the wall of the waveguide and of a movable receiver antenna with high directivity. From the radiation pattern of the leaky-wave antenna, as measured by the receiver antenna, the spectrum of the modes propagating in the waveguide is deduced.