A novel device for multimode analysis in oversized waveguides

An instrument is presented which allows mode analysis of microwaves in oversized waveguides by measuring the spectrum of axial wave numbers. 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.