In this article, the design of a frequencyswitchable, square-shaped microstrip patch antenna with simultaneous circular-polarization (CP) reconfigurability is presented and experimentally verified. From the measurement of a fully functional prototype, it is confirmed that the resonant frequency of the proposed antenna can be continuously altered between 1.97 and 2.42 GHz by electronically varying its effective length. A wideband 90° phase-shifting and switching network is also designed to excite the antenna for generating CP radiation at all the tunable frequencies and altering the sense of rotation [both left-hand CP (LHCP) and right-hand CP (RHCP)]. More importantly, the antenna shows an axial ratio (AR) value that is less than 3 dB within a wide beamwidth (130-150°) at all the tuning states, and it has a maximum realized gain of 5.8 dB isotropic circular (dBic) at 2.42 GHz. The frequency with CP-reconfiguring characteristics makes the proposed antenna suitable for advanced wireless communication systems operating in the S-band, which can withstand both frequency-based challenges and signal-quality issues arising due to climatic changes.

中文翻译：

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具有频率和圆极化可重构性的方形微带天线：一种方法 [天线应用专区]

在本文中，提出了一种具有同步圆极化 (CP) 可重构性的频率可切换方形微带贴片天线的设计并进行了实验验证。通过对全功能原型的测量，证实了所提出的天线的谐振频率可以通过电子方式改变其有效长度在 1.97 和 2.42 GHz 之间连续改变。还设计了一个宽带 90° 相移和开关网络来激发天线，以在所有可调谐频率下产生 CP 辐射并改变旋转方向 [左手 CP (LHCP) 和右手 CP (RHCP)] . 更重要的是，该天线在所有调谐状态下在宽波束宽度（130-150°）内显示出小于 3 dB 的轴比 (AR) 值，并且其最大实现增益为 5。2.42 GHz 时为 8 dB 各向同性圆形 (dBic)。具有 CP 重配置特性的频率使所提议的天线适用于在 S 波段中运行的高级无线通信系统，该系统可以承受由于气候变化引起的基于频率的挑战和信号质量问题。