Measured, simulated, and analytical fields radiated by patch antennas conformal to spherical geometries

Abstract

Summary form only given. The electromagnetic fields radiated by class of patch antennas conformal to spherical geometries are discussed in this paper. The fields of these antennas are determined analytically, computer simulated, and the results compared to measured data. From an analytical standpoint, the radiated fields are determined though the use of the classical cavity model. However, the spherical "ground plane" housing the antenna can have a pronounced effect on the radiation pattern. These effects on the pattern are dependent on the radius of curvature of the ground plane itself and make this a very different problem from that of a patch antenna mounted on a planar ground plane. These effects are discussed from an analytical and modeling standpoint and then compared to measured data. Among the patch geometries considered are the cap-like patch antenna, a cap patch with a wedge removed, a ring antenna, and a sector antenna. It is shown that the fields radiated by the antenna are very closely approximated by those radiated by patch antenna in cylindrical geometries (planar ground planes) as the radius of curvature becomes large. Because of the spherical geometry inherent to this application, some consideration must be given to the underlying ground plane and its size relative to the size of the patch. A quantitative study is presented as a means to examine these effects. Once the parameter of the size of the ground plane relative to the size of the patch antenna is understood, it becomes possible to specify frequency range limitations for the patch/ground plane structure. These complexities are also addressed.