Dielectric coated metal spherical antennas excited in the symmetric tm mode at microwave frequencies

Theoretical and experimental work on the radiation characteristics of the dielectric-coated metal spherical antenna are reported. Expressions for the radiated field and gain have been derived by an approximate method. Using these expressions, the radiation patterns and gain ofa number of antennas of various dimensions have been calculated and verified experimentally. The measured values of the input impedance of the antennas are also reported.