Equivalent Circuit Model of Coaxial Probe-Fed Quasi-Lumped Element Resonator Antenna

Abstract

Equivalent circuit model of a coaxial probe-fed quasi-lumped element resonator antenna is proposed. The proposed resonator is a periodic interdigital lumped element structure whose resonance does not depend on the electrical length but instead on some intrinsic circuit components, with attendant small size as a premium. The derived equivalent circuit components are extracted using the Agilent Advance Design System (ADS) software. The equivalent circuit model of the coaxial-feed probe is derived based on the simplest uniform-current model of a coaxial probe based on assumption that 1) all the higher-order evanescent have been included analytically in the parasitic circuit elements, and 2) only the propagating modes needs to be considered. The entire structure is further investigated using numerical EM solver such as finite integration technique (FIT) method in order to further compare the level of agreement. The derived equivalent circuit model has been validated by analytical formulae, numerical simulations, and measurement-based method.