Electromagnetic Modeling of Spherically Stratified Lenses Illuminated by Arbitrary Sources

This communication presents an accurate and computationally efficient method for designing spherical lens antennas. The method is based on spherical-wave modal expansion of both the electromagnetic field scattered by a multilayer lens and the far-field radiation pattern of a feed antenna. The two expansions are connected by transforming the fields from the local to the global coordinate system, i.e., by determining the equivalent current sources of the spherical lens Green's function. An important benefit of this method lies in the simplicity of implementing various feeding antennas in the design process. To verify the method, the results of the analysis are compared with measured radiation patterns of Luneburg lens antennas. Finally, the design guidelines for optimization of the whole lens antenna system are also discussed in the communication.