In this paper, a tri-band metamaterial (MTM) loaded compact monopole antenna is proposed. In the first step of design procedure, a rectangular monopole antenna is improved by replacing the corresponding rectangular patch with a ring resonator. As a result, the first obtained operating frequency is decreased from 2.95 to 2.46 GHz. Then, this operating frequency is reduced to 2.02 GHz utilizing an MTM geometry in the antenna structure. The geometry parameters of the proposed antenna are optimized to provide the applicability for 3G, WLAN, and WiMAX applications. The impedance bandwidths of 600, 1080, and 220 MHz are obtained at 2.02–2.62, 3.48–4.56, and 5.12–5.34 GHz, respectively. Moreover, the equivalent circuit of the proposed antenna has been extracted. The proposed equivalent circuit model is validated through a comparison with corresponding simulation results. The proposed antenna is compact, low profile, via-less, and provides easy fabrication. Considering the first resonance frequency, a compactness of 32% is achieved in comparison to the corresponding unloaded monopole antenna.

在本文中，提出了一种加载三频超材料（MTM）的紧凑型单极天线。在设计过程的第一步中，通过用环形谐振器替换相应的矩形贴片来改进矩形单极天线。结果，第一个获得的工作频率从 2.95 降低到 2.46 GHz。然后，利用天线结构中的 MTM 几何结构将该工作频率降低到 2.02 GHz。建议天线的几何参数经过优化，可适用于 3G、WLAN 和 WiMAX 应用。分别在 2.02–2.62、3.48–4.56 和 5.12–5.34 GHz 获得了 600、1080 和 220 MHz 的阻抗带宽。此外，还提取了所提出天线的等效电路。通过与相应的仿真结果进行比较，验证了所提出的等效电路模型。所提出的天线是紧凑的、低剖面的、无过孔的，并且易于制造。考虑到第一谐振频率，与相应的空载单极天线相比，实现了 32% 的紧凑性。