Moment method calculation of the propagation constant for leaky-wave modesin slotted rectangular waveguide

A moment method analysis procedure is described to determine the aperture f ield distribution in a finite-length straight longitudinal slot cut in the broad wall of a rectangular waveguide. The waveguide is fed from one end wi th the dominant waveguide mode, while the other end of the waveguide is sho rted, exactly at the far end of the slot. From the aperture distribution th e far-field radiation pattern is then computed, and from the radiation patt ern the attenuation and phase constants of the leaky-wave mode in the waveg uide are determined. The method of determining the propagation constant fro m the radiation pattern is an often used experimental technique to determin e leaky-wave propagation constants. Computed data is compared to measured d ata, and good correspondence observed. This propagation constant data can b e used to design long meandering leaky-wave slot antennas.