The eccentrically insulated circular loop antenna

The analysis for the circular loop antenna in a concentric insulating sphere is extended to the case where the loop is eccentrically located in the sphere, that is to say, coaxial with the sphere but not concentric. Both the transmitting and receiving antennas are treated. Parametric studies are used to determine the effect of the electrical size of the loop and sphere, the eccentricity, and the electrical properties of the media on the directivity of the antenna. The field pattern for the loop is found to be a vertical beam with approximately linear polarization when the electrical size of the loop is near that for resonance in the insulation, β1b ≈ 1.0, the ratio of the permittivity of the surrounding medium to that in the insulation εer2/εer1 is large, and when the eccentricity d/c is high. Measured driving point admittances and field patterns of model antennas are compared with theoretical calculations and found to be in good agreement. A limited experimental investigation indicates that the circular loop antenna with an eccentric cylindrical insulation will have directive properties similar to those obtained with a spherical insulation.