H-polarized scattering from single and multiple elongated cavities

H-polarized scattering is investigated for perfectly conducting surfaces containing one, two, or many parallel grooves. Incidence is transverse to the axes of the cavities, which are of rectangular cross section and on the order of the incident wavelength in size. For cases with many regularly spaced cavities, a Floquet and waveguide mode-matching scheme is used that incorporates the effects of a nonplanar nonuniform incident beam, a corresponding receiving pattern, and a finite target size. For single grooves, point matching between waveguide mode and integral expressions is used. Measured backscatter patterns show negligible coupling effects for two nearby cavities; thus, pattern multiplication using single-cavity patterns is applied to obtain results for dual-cavity structures. Calculated patterns for single-cavity and multiple-cavity targets agree well with Ka-band laboratory measurements and show grating type behavior for two or more scattering cavities. The results suggest an ability to estimate individual cavity width and separation for sets of similar cavities, and to estimate cavity separation even for dissimilar cavities.<>