A compact circularly polarized (CP) patch antenna is presented for modern communication systems. The prospective antenna consists of a microstrip-line inset-fed rectangular patch and a defected ground plane. A rotated rectangular slot and a modified electric-inductive-capacitive (m-ELC) resonator are introduced in the patch and the ground plane to achieve multiband behaviour. A corner of the radiating patch is truncated and an arrow-shaped stub is introduced for generating circular polarization. The physical area of the substrate is 0.26λ0 × 0.22λ0, and the radiator size is 0.16λ0 × 0.14λ0, where λ0 is the free-space wavelength estimated at the lowest frequency. The measured (S11≤-10 dB) bandwidths of the antenna are 80 MHz (3.58%) at 2.23 GHz, 75 MHz (2.64%) at 2.84 GHz, 80 MHz (2.50%) at 3.19 GHz, and 70 MHz (1.82%) at 3.83 GHz. The measured 3-dB axial ratio bandwidths are 40 MHz (1.41%), 100 MHz (3.12%), and 60 MHz (1.57%) at 2.84, 3.20 and 3.82 GHz, respectively. The proposed planar antenna design does not need dual-feed or multi-layered patches for achieving multiple CP bands. It offers easy integration with the printed circuits of the communication systems.

中文翻译：

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具有改进的电感电容谐振器的四波段多极化天线

提出了一种用于现代通信系统的紧凑型圆极化 (CP) 贴片天线。预期天线由一个微带线插入馈电矩形贴片和一个有缺陷的接地平面组成。在贴片和接地平面中引入了一个旋转的矩形槽和一个改进的电感电容 (m-ELC) 谐振器，以实现多频带行为。辐射贴片的一角被截断并引入箭头形短截线用于产生圆极化。基板的物理面积为0.26λ0× 0.22λ0, 散热器尺寸为 0.16λ0× 0.14λ0， 在哪里λ0是在最低频率处估计的自由空间波长。实测（S11≤-10 dB) 天线的带宽在 2.23 GHz 时为 80 MHz (3.58%)，在 2.84 GHz 时为 75 MHz (2.64%)，在 3.19 GHz 时为 80 MHz (2.50%)，在 3.83 GHz 时为 70 MHz (1.82%) . 在 2.84、3.20 和 3.82 GHz 时测得的 3-dB 轴比带宽分别为 40 MHz (1.41%)、100 MHz (3.12%) 和 60 MHz (1.57%)。所提出的平面天线设计不需要双馈电或多层贴片来实现多个 CP 频段。它提供与通信系统印刷电路的轻松集成。