A Compact Dual-Band Antenna Enabled by a Complementary Split-Ring Resonator-Loaded Metasurface

In this paper, the design of a compact dual-band antenna with operational bands centered at 1.9 and 2.5 GHz is introduced and validated numerically as well as experimentally. The proposed antenna is comprised by placing a monopole feeding antenna above an engineered multilayer metasurface (MS) which functions as an artificial ground plane. Moreover, complementary split-ring resonator structures are incorporated into the multilayer MS design to realize the dual-band operation of the proposed monopole-MS integrated antenna system. Dispersive analysis of the MS unit cell reveals the underlying radiation mechanism of the antenna. It is observed that the designed MS resonates in both frequency bands with a resonance mode pattern resembling that of the TM
₁₀
mode of a rectangular patch antenna, thereby yielding a broadside radiation pattern in both bands. The overall footprint of the antenna is only 0.062λ
₀
²
, where λ
₀
is the free space wavelength at 1.9 GHz. Importantly, by using the proposed artificial ground plane, even with a highly miniaturized form factor, the antenna still maintains a peak gain of above 5 dBi and a front-to-back ratio higher than 6 dB within the two operational bands.