Mutual coupling between rectangular slot antennas on a conducting concave spherical surface

The surface fields excited by a horizontal magnetic source located on a conducting concave spherical surface have been formulated. The field expressions are obtained as a combination of ray-optical fields and simplified integrals under the condition that the radius of the spherical surface is much greater than the wavelength. Numerical calculations have been performed, and the calculated results for the surface fields have been corroborated with experiments. The results of these basic studies have been used in calculating the mutual coupling between rectangular slot antennas on the conducting concave spherical surface assuming the aperture field as the dominant mode in the wave guides connected with the slots. The numerical results have been compared with those for slots on a convex conducting surface. Experimental investigation of the mutual coupling has also been carried out.