Design and Modeling of Wideband Planar Antennas Using Characteristics Modes

Origin of wideband nature and radiation behavior in many broadband antenna structures is not clearly understood. In this article, we have attempted to clarify those phenomena using characteristic mode (CM) analysis along with equivalent circuit (EC) modeling. By modeling the modal impedance of antenna for a large bandwidth, considering natural resonances and anti-resonances, the EC models are developed for various wideband antennas. It is observed that the reactive loading and resonant mode coupling effects are largely contributing in the formation of wideband and far fields of antenna. These models can be used in SPICE simulators to study the effective communication between wireless transmitter and receiver systems without an EM solver. A novel design method is proposed on the development of wideband antennas using a modal impedance model and coupled mode theory of resonant modes. This method yields accurate design to achieve desired center frequency and bandwidth using structural modifications.