In this manuscript, an antenna design configured for dual-band circularly polarized (DBCP) characteristics is presented. The proposed design is quite compact (0.63 λ g × 0.63 λ g × 0.04 λ g) and comprises a mushroom-shaped monopole with a modified ground structure (MGS). In the proposed antenna structure, dual-band CP behavior is generated through a tunable side stub joined orthogonally with the feed patch and reshaping the wide square slot. The impedance bandwidth is measured as 2900 MHz ranging from 1.32 to 4.22 GHz in the lower frequency band (Band 1); however, 980 MHz from 4.78 to 5.76 GHz in the higher frequency band (Band 2). The 3-dB AR bandwidth is measured as 370 MHz (from 3.54 to 3.91 GHz)in the lower frequency band; whereas, it is measured as 650 MHz (from 5.07 to 5.72 GHz) in the higher frequency band. The measured gains spread from 2.5 to 8.3 dBi with a maximum gain of 8.3 dBi in the lower frequency band, whereas 4.8 to 7.05 dBi with a 7.05 dBi maximum gain in the higher frequency band, respectively. The cross-polar rejection is observed greater than 14 dB. Besides, 3-dB half-power beamwidths are seen as 86° & 84°, and 87° & 86° in the x-z and y-z planes for the lower and higher frequency bands, respectively.

中文翻译：

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修正地平面的双频圆极化蘑菇形单极天线的表征

在这份手稿中，提出了一种针对双频带圆极化 (DBCP) 特性配置的天线设计。建议的设计非常紧凑（0.63λ G× 0.63λ G× 0.04λ G) 并包括一个蘑菇形单极子，具有改进的地面结构 (MGS)。在所提出的天线结构中，双频 CP 行为是通过与馈电贴片正交连接的可调谐侧短截线和重塑宽方形槽产生的。阻抗带宽测量为 2900 MHz，范围从 1.32 到 4.22 GHz，在较低频段（Band 1）；但是，在较高频段（频段 2）中，从 4.78 到 5.76 GHz 为 980 MHz。3-dB AR 带宽在较低频段测量为 370 MHz（从 3.54 到 3.91 GHz）；而在较高频段测量为 650 MHz（从 5.07 到 5.72 GHz）。测量的增益从 2.5 扩展到 8.3 dBi，在较低频段的最大增益为 8.3 dBi，而在较高频段的最大增益为 4.8 到 7.05 dBi，分别为 7.05 dBi。观察到交叉极性抑制大于 14 dB。此外，3-dB 半功率波束宽度被视为 86° 和 84°，而 87° 和 86° 在X-z和是的-z分别用于较低和较高频段的平面。