  In experimental physics, it is essential to understand electromagnetic (EM)
wave scattering across EM spectrum, from radio waves to X-rays, and is pivotal
in driving photonics innovations. Recent advancements have uncovered phenomena
like bound states in the continuum (BICs) and parity-time (PT) symmetric
systems, which are closely associated with the characteristics of the
scattering matrix and are governed by passivity and causality. The emergence of
complex frequency excitations has transcended the constraints imposed by
passivity and causality in a system, revealing effects such as virtual critical
coupling and virtual gain. However, applying the concepts of complex frequency
excitation in more complicated systems remains challenging. In this work, we
demonstrate the extension of the lumped element model of circuit theory to the
analysis of anomalies in light scattering in the complex frequency domain. We
demonstrate that the circuit model approach can facilitate design and analysis
of effects such as virtual perfect absorption, BICs, real and virtual critical
coupling, exceptional points, and anisotropic transmission resonances (ATRs).
These findings broaden comprehension of EM wave phenomena and pave the way for
significant advancements in photonics, offering new methods for designing and
optimizing optical devices and systems with broad-ranging applications.
