Diffraction by Parallel Plates with Application to Lens Antennas.
ILLINOIS UNIV AT URBANA ELECTROMAGNETICS LAB
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Scattering of an incident plane, or cylindrical, wave by a staggered parallel-plate waveguide is examined. Of particular interest are the modal coefficients of the unattenuated modes in the waveguide when the incident fields is an E-wave. Several past approaches based on ray techniques are critically examined. It is found that they are not applicable when the stagger is small or when the incident field is a cylindrical wave. For the latter incidence, we introduce here an aperture field method, in which the modal coefficients are calculated through the Fourier decomposition of the scattered field at the waveguide aperture. To determine this scattered field, we apply the uniform asymptotic theory for the primary contribution, and the spectral theory for the first interaction. Extensive numerical data show that the aperture field method gives accurate results in canonical problems whose exact solutions are known. As an application to the design of the constrained waveguide lens antenna, out method enables one to determine the field distributed over the lens in a more exact manner. Author
- Electrical and Electronic Equipment