A Circuit Model for Electrically Small Antennas

A circuit model for electrically small antennas is introduced that is based on their frequency-dependent polarizabilities. This model is useful for straightforwardly analyzing several different small antenna geometries. A negative permittivity sphere, shell, and spheroid are all analyzed. An inductively loaded dipole, a top-hat loaded dipole, and a spherical sheet impedance are also analyzed. The circuit model provides the antenna's radiation quality factor (Q), radiation efficiency (η
_rad
), and bandwidth. It also offers insight into the operation of the antenna which can aid and simplify design.