Equivalent Circuit Model for a Waveguide Fed Dual Rectangular Slot Antennas

An equivalent circuit is used to model a waveguide fed dual rectangular slot antenna to understand the slot resonance and mutual coupling effect between two slots. The circuit models including LC circuit, waveguide section, parallel RLC combination, and transformer are introduced to describe the scattering behaviors of each single slot. The mutual coupling effect acts like an absorptive band-stop filter which can be modeled as shorted serial RLC combination. Reflection response
$S_{11}$
and
$S_{21}$
are analyzed in terms of the circuit parameters. The results obtained from the equivalent circuits are validated by the scattering parameters and current distribution using HFSS simulation, and exhibit good agreement over the frequency band of interest.