Physically Realizable Antenna Equivalent Circuit Generation

This work introduces a new equivalent circuit generation method which can compute an accurate equivalent circuit representation for the known/measured impedance characteristics of antennas, which may assist in matching circuit design, non-Foster matching network design, and deep-learning antenna design. The method utilizes a modified Drude-Lorentz resonator representation inspired by optical material dispersion modeling to create multiple sub-circuits based on determined resonances in the impedance spectrum. Each computed sub-circuit is necessarily composed of physically realizable resistors, capacitors, and inductors, and they are connected in series to accurately reconstruct the device's corresponding impedance characteristics over a specified region of interest. The process is automated and applicable to a wide range of antennas and electromagnetic devices with multiple resonance phenomena. Current equivalent circuit design methods are limited by a lack of generalization and can require complex, active, or non-realizable circuit topologies. The proposed Drude-Lorentz-based approach can provide valuable insight into an antenna's resonant behavior while remaining general-purpose and only requiring passive components which are physically realizable. This improved generality is achieved by not requiring physical insights, but rather only utilizing the impedance data alone. Additionally, the method creates simpler circuits than other general methods, requiring less components and component types. This method is employed to create equivalent circuits of four different exemplary types of antennas, a patch antenna, a loop antenna, a spherical helix antenna, and a metantenna unit cell. The impedances generated from these circuit examples are compared with results of their full-wave simulation counterparts and found to be in excellent agreement.