The Electrically Small Elliptical Loop with an Oblate Spheroidal Core

The fundamental properties of an electrically small elliptical loop wound on an oblate spheroidal core are calculated using quasi-static theory. Closed-form expressions are derived for the elements of a complete equivalent circuit, including the inductance and capacitance, and radiation, conductor, and core-loss resistances. It is shown that the bandwidth and efficiency are greatly increased by the use of a ferrite core. Losses in the core are computed for two low-loss ferrites. Although the primary objective is to simplify the design of a transmitting antenna for use in the lower part of the HF band, 2-4 MHz, the theory presented is equally valid for the design of receiving antennas and for other frequencies.