Radiating slots near resonance in a broad wall of a rectangular waveguide

The off-resonant characteristics of compound slots are investigated. A pair of coupled integral equations in terms of the dominant component of the electric field in both apertures was obtained by enforcing the continuity of the longitudinal magnetic field in the slot apertures. The integral equations were then solved by the method of moments. Over a small frequency range near resonance, the magnitude of the aperture electric field and forward and backward scattered TE/sub 10/-mode amplitudes exhibit slow variations, and their phases nearly track each other. The phase variation of S/sub 11/ over a 2% change in slot length from resonance is shown for a standard-height X-band waveguide and a half-height waveguide. The phase variation is greater for thick wall slots and for larger waveguide b dimension. The phase variation is significantly reduced for larger offsets and for larger values of tilt angles.<>