Accurate modelling of anti-resonant dipole antennas using the method of moments

The authors demonstrate that the difficulties encountered when modelling anti-resonant antennas are primarily due to the conventional variable gap source model which is commonly employed in thin-wire moment method codes. An alternative source model is introduced, for use in analysing this class of antennas, where the essential feature is that the gap width of the feed region remains fixed. The fixed gap model is compared to the variable gap model for both a half-wave dipole, where the variable gap is still a valid source model, and for a full-wave anti-resonant dipole, where the fixed gap source is shown to be superior to the variable gap model.