In this article, a microstrip antenna having circular polarization switching capability is presented. This antenna consists of a circular-shaped radiating patch with a single co-axial probe feed line. The polarization reconfigurability is achieved by introducing four symmetrical U-shaped slots and silicon PIN diodes on the radiating patch. A prototype of the design is fabricated on an FR-4 substrate with overall dimension of 70 × 70 × 1.6 mm to verify the performances. The measured results of the antenna exhibit an impedance bandwidth (S 11 < −10 dB) of 5% in the frequency range of 2.37–2.49 GHz. The maximum gain of the antenna is found to be 2.99 dBic at 2.43 GHz. The antenna shows stable radiation performances at 2.4 GHz with 4.1% of 3-dB axial ratio bandwidth, and more than 105° of 3-dB axial ratio beamwidth for both right-hand circular polarization and left -hand circular polarization which make it suitable for ISM band Smart city applications.

中文翻译：

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用于 ISM 频段智慧城市应用的 RHCP 和 LHCP 极化可重构微带天线

本文介绍了一种具有圆极化切换能力的微带天线。该天线由一个圆形辐射贴片和一条同轴探针馈线组成。通过在辐射贴片上引入四个对称的 U 形槽和硅 PIN 二极管来实现极化可重构性。该设计的原型在 70 × 70 × 1.6 mm 整体尺寸的 FR-4 基板上制造，以验证性能。天线的测量结果表现出阻抗带宽 (小号 11< -10 dB) 在 2.37–2.49 GHz 频率范围内为 5%。发现天线的最大增益在 2.43 GHz 时为 2.99 dBic。该天线在 2.4 GHz 下具有稳定的辐射性能，具有 4.1% 的 3-dB 轴比带宽，右侧圆极化和左侧圆极化均超过 105° 的 3-dB 轴比波束宽度，使其适用于ISM 频段智能城市应用。