In this letter, a compact omnidirectional dual‐band antenna is designed for wireless local area network applications. The proposed antenna is printed on the two sides of an FR4 substrate that the total dimension is 12 × 46 × 0.5 mm³. A dipole antenna is used to cover the lower operating band (2.45 GHz), while a capacitances‐loaded patch generates a higher resonance (5.5 GHz). This antenna has a good impedance matching in the operation band, and the gain is 2.28 and 4.42 dBi in the lower and upper bands, respectively. To address the problem that the performance will drastically decline when the antenna is located on a ground, a quarter wavelength spiral line is employed to decrease the negative effect of the ground. Two proposed dipole antennas, placed on a horizontal ground as a MIMO antenna system, are analyzed with different configurations. The results reveal that the proposed method can effectively reduce the ground plane effect and improve the diversity performance, which has huge potential applications in MIMO system.

中文翻译：

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紧凑型全向双频偶极天线，具有减小的地平面效应

在这封信中，紧凑型全向双频天线是为无线局域网应用设计的。拟议的天线印在FR4基板的两侧，基板的总尺寸为12×46×0.5 mm ³。偶极天线用于覆盖较低的工作频带（2.45 GHz），而电容加载的贴片会产生较高的谐振（5.5 GHz）。该天线在工作频带中具有良好的阻抗匹配，并且在较低和较高频带中的增益分别为2.28和4.42 dBi。为了解决当天线位于地面上时性能将急剧下降的问题，采用四分之一波长螺旋线来减小地面的负面影响。使用不同的配置分析了两个建议的偶极子天线，它们作为MIMO天线系统放置在水平地面上。结果表明，该方法可以有效降低地平面效应，提高分集性能，在MIMO系统中具有巨大的应用潜力。