Abstract-This paper studies the characteristics of a constant-K lens when considered as a possible substitute for a Luneburg lens in a reflector. The competitiveness of the substitute lens is investigated in its 2D analogue, by comparing the backscattering radar cross section for the range of D/λ ∈ (0, 200). The performance of cylindrical reflectors with either a constant-K lens or a cylindrical Luneburg lens (approximated by a finite number of stepped-index dielectric layers) when illuminated by an electromagnetic plane wave is studied using the semi-analytic Method of Regularization. Because of similar underlying physical principles, these studies provide an insight into the 3D analogue. The radar cross section calculations of the two reflectors for incidence angles varying from normal to grazing incidence show that the cheaper-to-manufacture constant-K lens reflector is able to provide a more powerful and stable backscattering performance than the cylindrical Luneburg lens reflector, for electrical sizes in the range considered.

This paper deals with the analysis of a spherical lens fed by an array of feed antennas. The spherical lens structure is accurately and efficiently analyzed by a spherical wave expansion method. The boundary element method is used for modeling of arbitrarily shaped feed antennas. Combining these two methods, a hybrid method is developed for accurate calculation of the input impedances and mutual coupling between the array elements, and the far-field radiation pattern. The main advantage of this approach is that all the electromagnetic interactions in the lens/array feed system are included in the analysis. Also, the feed antennas of complex shape may be accurately modeled while earlier developed methods, for the analysis of this type of antennas, are based on some assumptions for the feed current distribution. Comparing to commercial software packages, the hybrid method significantly reduces both computational time and memory requirements while providing high accuracy.