Microwave lens matching by simulated quarter-wave transformers

The reflections from the surface of a dielectric lens may be cancelled by a quarter-wavelength layer of refractive index intermediate between that of air and the lens medium. The possibility of simulating a quarter-wave matching section by perturbing the boundary of the lens is described in this paper. Some of the configurations considered are corrugated surfaces, arrays of dielectric cylinders, and arrays of holes in the dielectric surface. In each case, a match may be obtained at a given frequency and angle of incidence by the proper adjustment of the depth of the perturbation, and of one other parameter such as the width of a groove.