Radiation properties of a thin wire loop antenna embedded in a spherical medium

Abstract

Formulas for certain radiation properties of a spherical antenna are derived theoretically. The antenna, which consists of a spherical medium, such as ferrite, with a thin wire loop embedded just below the surface in an equatorial plane, is driven by a slice generator. For the spherical medium, the permeabilityK_{m}and the dielectric constantK_{e}are assumed to be scalars and, in general, complex. The solutions are facilitated through the expansion of the fields in terms of characteristic orthogonal spherical vector wave functions. The properties for which formulas are derived are current distribution, input impedance, input power, radiated power, power loss in the spherical medium, and the efficiency of the antenna. For radiation resistance, not only the general case formula but also the formula for electrically small antennas is given, and the difference between these formulas, for media assumed lossless, is shown graphically.