Effect Metamaterial Gap Orientation on the Performance Microstrip Antenna at 2.3 GHz

Abstract

This study investigates the effect of gap orientation in a 2 × 2 Rectangular Split-Ring Resonator (RSRR) metasurface on the simulated performance of a microstrip antenna operating at 2.35 GHz. The antenna was modeled using FR-4 substrates and evaluated using a three-dimensional full-wave electromagnetic simulator. Five configurations were investigated: the antenna-only configuration and antennas integrated with right-, left-, upward-, and downward-facing RSRR gaps. The antenna-only configuration produced an S11 of approximately −26 dB, a VSWR of 1.1059, and a maximum gain of 2.512 dBi. The left- and right-facing configurations produced nearly identical responses, with S11 values of approximately −43 dB, VSWR values of approximately 1.013, and maximum gains of 3.643 dBi. Both configurations achieved a bandwidth of 100 MHz, corresponding to a fractional bandwidth of 4.26%, and increased the maximum gain by 1.131 dB compared with the antenna-only configuration. In contrast, the upward- and downward-facing configurations shifted the resonant frequency to approximately 2.23–2.24 GHz and therefore did not provide optimum performance at the target frequency. All configurations maintained directional radiation patterns with broadside main beams, while their surface-current distributions demonstrated that the electromagnetic coupling varied with gap orientation. Overall, the left- and right-facing RSRR gap configurations provided the best simulated performance at 2.35 GHz. Future work will include antenna fabrication and experimental measurements to validate the simulation results.