This letter proposes a newly designed differentially fed dual‐band circularly polarized (CP) printed slot antenna (PSA). The antenna consists of two oppositely fed halberd‐shaped strips and an S‐shaped slot. By configuring the antenna structure in rotationally symmetric fashion, the fields radiated by any two rotationally symmetric parts of the CP PSA will be constructive when excited differentially and destructive when in common‐mode (CM) operation. Thus, good differential‐mode (DM) performance and high CM rejection can be achieved. In particular, in both CP bands the radiation patterns of the proposed antenna are of the same CP sense, and the CP beams are wide and stable. Measurement shows the proposed differentially fed dual‐band CP PSA has a lower (higher) 10‐dB DM impedance band of 2.09 to 2.85 (5.06‐5.89) GHz and a 3‐dB DM axial‐ratio band of 2.32 to 2.59 (5.13‐5.86) GHz, corresponding to a CP fractional bandwidth of 10.9% (13.3%). Besides, in the displayed frequency region of 2‐6 GHz, the CM signals can be effectively suppressed, with the measured CM return loss smaller than 2.96 dB. The conversion of DM input signals into CM reflected signals is even smaller, with the measured DM‐to‐CM conversion less than −32 dB.

中文翻译：

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高共模抑制比的差分馈送双频圆极化印刷缝隙天线

这封信提出了一种新设计的差分馈送双频圆极化（CP）印刷缝隙天线（PSA）。天线由两个反向馈入的戟形带和一个S形槽组成。通过以旋转对称的方式配置天线结构，CP PSA的任意两个旋转对称部分所辐射的场在差分激励时将具有建设性，而在共模（CM）运行时则具有破坏性。因此，可以实现良好的差模（DM）性能和高CM抑制性能。特别地，在两个CP频带中，所提出的天线的辐射方向图具有相同的CP方向，并且CP波束宽且稳定。测量表明，建议的差分馈送双频带CP PSA具有2.09至2.85（5.06-5）的较低（较高）的10dB DM阻抗带。89）GHz和2.32至2.59（5.13-5.86）GHz的3 dB DM轴向比率带，对应于10.9％（13.3％）的CP分数带宽。此外，在显示的2-6 GHz频率范围内，可以有效抑制CM信号，测得的CM回波损耗小于2.96 dB。DM输入信号到CM反射信号的转换甚至更小，测得的DM到CM的转换小于-32 dB。