Field of a circular loop near a symmetrical spherical cap

The field of a thin circular loop antenna symmetrically placed near a conducting spherical cap is computed. The total field is expressed in terms of three modal expansions in three different regions. Most of the unknown coefficients are obtained analytically. Some are solved numerically by using point matching. The same problem is also solved numerically by the Method of Moments, where the surface of the cap is approximated by planar triangular patches. Computed results obtained by both methods are in excellent agreement.