Demonstration of the dark mode excitation in a matched square patch antenna

Abstract This paper proposes an asymmetric feeding mechanism designed to excite poorly radiating modes while maintaining a match to the antenna’s input impedance. We explore the excitation of a specific type of non-radiating electromagnetic source known as the ‘dark mode’ , which is linked to the excitation of the higher-order magnetic quadrupole resonance of a square microstrip antenna operating in the microwave S-band. We conducted a multipole scattering analysis to validate our findings by spatially integrating the surface current distributions induced on the antenna structure. We studied the radiation effects of the antenna through simulations using full-wave commercial software, in computations with Finite-Difference Time Domain (FDTD) simulations, and conducted experiments with a Vector Network Analyzer in an anechoic chamber.