RAY-TRACING ON EXTENDED HEMISPHERICAL AND ELLIPTIC SILICON DIELECTRICLENSES

In this paper, extended hemispherical and elliptical silicon dielectri c lenses are compared by means of ray tracing. It is shown that the op tical focuses of two lenses are not at same position though the ellipt ical lens is synthesized from an extended hemispherical lens by carefu lly choosing a particular extension length as stated in reE[1]. It may be used to explain why the best compromise between alignment, directi vity and Gaussian-coupling effciency will be obtained if the feed ante nna is placed at the region between 2.2 mm and 2.4 mm of extension len gth (for 13.7 mm diameter lens, dielectric contant - 11.7).