A Circuit Model for the Design of Self-Excited EBG Resonator Antennas With Miniaturized Unit Cells

A circuit model based on Bloch theory is introduced to simplify analysis and design of antennas composed of thick metal electromagnetic band-gap (EBG) cells with large intercell coupling capacitance. The cells are composed of thick metal patches periodically deployed on a metal-backed dielectric slab. Two versions of cells are presented that provide large intercell capacitance, one with narrow high aspect ratio (HAR) gaps between cells and the other with interdigitated gaps between cells. This large capacitance reduces the antenna resonance and dramatically miniaturizes the EBG cells. Three cascaded unit cells are used to demonstrate the applicability of the circuit model to characterize the recently introduced self-excited EBG resonator antenna. Full-wave numerical analysis and experimentation validate the robustness and accuracy of the model over large variations in electrical/physical cell dimensions.