In this paper, a compact circularly polarized quadrifilar antenna with planar inverted-F antenna (PIFA) elements is presented. The proposed antenna consists of four PIFA elements and a Wilkinson divider-based feed network fabricated on FR-4 substrate (ɛr = 4.4, loss tangent = 0.02, thickness = 1.6 mm). The total size of the antenna is 120 × 120 × 13.2 mm3. Impedance matching with a reflection coefficient <−15 dB and an axial ratio (AR) <3 dB are achieved over the global ultra-high frequency (UHF) radio frequency identification (RFID) frequency band and beyond. The realized gain ranges from 2.25 to 3.75 dBic within the frequency band of interest from 860 to 960 MHz with a directional radiation pattern. The proposed antenna is compact, low-cost and extremely wideband in terms of matching and AR compared to state-of-the-art UHF RFID reader antennas.

中文翻译：

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用于 UHF RFID 阅读器的带有 PIFA 元件的紧凑型宽带圆极化四线天线

在本文中，提出了一种带有平面倒 F 天线 (PIFA) 元件的紧凑型圆极化四线天线。所提出的天线由四个 PIFA 元件和一个基于威尔金森分压器的馈电网络组成，制造在 FR-4 基板上（εr= 4.4，损耗角正切 = 0.02，厚度 = 1.6 mm）。天线总尺寸为 120 × 120 × 13.2 mm3. 在全球超高频 (UHF) 射频识别 (RFID) 频带及以上范围内实现了反射系数 <-15 dB 和轴比 (AR) <3 dB 的阻抗匹配。在 860 至 960 MHz 的感兴趣频带内，实现的增益范围为 2.25 至 3.75 dBic，具有定向辐射模式。与最先进的 UHF RFID 阅读器天线相比，所提出的天线在匹配和 AR 方面具有紧凑、低成本和极宽的带宽。