Experimental study of a diffraction reflector

A microwave antenna has been designed and constructed on the principles of parageometric optics formulated by Toraldo di Francia and on principles similar to those of Fresnel rings and the diffraction grating. Its surfaces are all zones of cones and are simple to construct. The chosen design parameters were incorporated in two
K
-band (
\lambda = 1.24
cm,
\lambda = 1.22
cm) models. Experimental results show good agreement with theory. Scanning characteristics are superior to those of the paraboloidal or spherical reflector, and spherical aberration and coma are minimized, and the effects of astigmatism are minimized by using a "compromise focus."