A numerical study on realizable broad-band and equivalent admittances for dipole and loop antennas

Some realizable broad-band equivalent circuits for straight-wire and wire-loop structures are developed. The realizability of the circuits is explored in terms of the positive-real (PR) function properties of the circuit admittances. The postulate of PR "terminal eigenadmittances" as couched by Pearson and Wilton [8] is generally supported in the numerical examples, but a potential counterexample-that of the quarter-driven wire-occurs as well. A "dominant pole-pair" approach leads to a quate satisfactory approximate synthesis for the structures studied here. The conduct of this approximate synthesis is described in the context of the Bott-Duffin synthesis procedure. The circuits developed are tested by comparing their computed transient response with the response of electrodynamic models for the same structures.