Suppression of spurious radiations of patch antennas using split‐ring resonators (SRRs)

The spurious radiation of patch antennas is suppressed by the band‐stop characteristic of split‐ring resonators (SRRs). The SRRs are located near the feed line of the upper substrate so as to couple the perpendicular magnetic field to the SRRs. The SRRs can be characterized with negative permeability and positive permittivity around the resonance frequency and, thus, waves cannot propagate. To eliminate the first and second spurious radiations, the design equations of a band‐stop filter using SRRs are suggested. The reflection coefficient and the far‐field radiation pattern of a patch antenna with SRRs are obtained via full‐wave simulation and measurement.