Triangular ray tube analysis of dielectric lens antenna

The dielectric lens is a viable alternative to the reflector as the main mission antenna to provide communication satellite services in the millimetre wave band. Of the various types of dielectric lenses available, the thin spherical lens is particularly suited for satellite usage. Its advantages are many, including low weight obtained through zoning, centre feeding with no blockage, circular symmetry for ease of fabrication and wide scanning capability with minimal gain loss. In addition, surface matching by means of circumferential slots is used to reduce weight further and minimise surface reflection loss. Most of the lens analyses published in the literature e.g. [1,2], are of the scalar ray tracing type where differentiation is not made between TE and TM incidences on the lens. Also, the effects of matching layers and zoning steps are not taken into consideration. In this paper, we are presenting an analysis approach that is valid for any type of dielectric lens where surface matching and zoning steps are correctly treated and the ray tracing contains both TE and TM components. As a result, we observe very good agreement between measurements and predictions of gain patterns for both thin spherical lens and thick shaped lens.