Broadband Stable-Gain Multiresonance Antenna Using Nonperiodic Square-Ring Metasurface

A multiresonance antenna based on a nonperiodic square-ring metasurface (MS) is proposed, which has large bandwidth and stable radiation gain. The nonperiodic MS radiator is formed by several adjustable square-ring patches and fed by a microstrip line through a coupling slot. By properly adjusting the widths of these square rings, different resonance modes can be inspired for the MS according to the characteristic mode analysis. Combined with the resonance mode of the coupling slot, multiple adjacent resonance frequencies occur and thus realize a wideband and consistent radiation. For demonstration, a C-band wideband antenna based on the proposed 4 × 4 square-ring MS units with a low profile of 0.06λ0 is accordingly designed and fabricated. The measured results indicate a large impedance bandwidth of 54% (4-7 GHz) and an extremely stable gain with 2 dB gain bandwidth of 32% (4.76-6.54 GHz).