Numerical simulations of patch antennas with stacked split-ring resonators as artificial magnetic substrates

Analytical studies have established that magnetic material substrates of patch antennas at microwave frequencies would reduce the resonant frequency of the antenna while essentially retaining the relative bandwidth. However, readily available magnetic materials exhibit high losses at microwave frequencies, which severely limits their applications at frequencies higher than about 1 GHz. Densely packed split-ring resonators have been recently proposed for microwave applications. In this work, densely packed arrays of split-ring resonators (SRR) are used as an artificial magnetic substrate to reduce the resonant frequency of a patch antenna. The SRR stacks embedded into a dielectric medium constitute an anisotropic magneto-dielectric substrate, allowing a considerable reduction of the resonant frequency of the antenna, while approximately preserving the relative bandwidth. Different configurations of the material are studied numerically using the finite-difference time-domain (FDTD) method.