Effective Q factor for spherical surface antennas

Abstract

The effective Q factor for self-resonant spherical surface antennas has been calculated in this study. A current sheet is assumed on the spherical surface and its radiated field is described in terms of the lowest TE and TM modes of the spherical wave expansion. Using the formula for stored energy of spherical mode, loss less Q factor is obtained. The effective Q factor is computed by multiplying the loss less Q factor and the radiation efficiency. The result is compared with non-resonant single mode case and with Chu limit.