A new type of tag antenna, which is made by placing four identical planar inverted-L antennas (PILAs) in rotational symmetry constellation, is proposed for designing a miniature on-metal tag antenna. It shows good omnidirectional characteristics in the azimuth plane. In the design, the directive radiation beams of the respective PILAs are tactfully combined to form a stable omnidirectional pattern. The proposed tag is compact with a small size of 40 mm × 40 mm × 1.6 mm (0.122 λ × 0.122 λ × 0.005 λ). Here, all the PILAs are inductively excited by a circular loop, which also introduces additional reactance for improving the impedance matching. The proposed tag antenna is able to achieve a stable read distance of 5.9 m on metal in the azimuth plane when it is tested using equivalent isotropic radiated power of 4 W. The operating frequency of the tag is stable and it is not affected much by changes in the backing metal.

中文翻译：

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用于全向 UHF 金属标签设计的环路馈电平面倒 L 天线 (PILA)


提出了一种新型标签天线，该天线是通过将四个相同的平面倒L型天线（PILA）放置在旋转对称星座中而制成的，用于设计微型金属标签天线。它在方位平面上表现出良好的全向特性。在设计中，各个PILA的定向辐射束巧妙地组合在一起，形成稳定的全向图案。所提出的标签结构紧凑，尺寸较小，为 40 mm × 40 mm × 1.6 mm (0.122 λ × 0.122 λ × 0.005 λ)。这里，所有 PILA 均由环形环路感应激励，这还引入了额外的电抗以改善阻抗匹配。当使用4 W的等效各向同性辐射功率进行测试时，所提出的标签天线能够在方位角平面上的金属上实现5.9 m的稳定读取距离。标签的工作频率稳定，受变化影响不大。在背衬金属中。