A novel method of designing a wideband dual-feed circularly polarized (CP) antenna is presented for different axial ratio (AR) requirements. By analyzing the output characteristic of the feed network for the dual-feed CP antenna, an approximate function is obtained and utilized to calculate the variances of the output magnitude and phase of the feed network under a required AR. Based on the analysis, different branch-line couplers are used for achieving wide AR bandwidths of less than 3, 2, and 1 dB, respectively. Compared to the traditionally used 3 dB coupler, the presented feed method can have an AR peak with the expected value at the center frequency and two AR valleys beside the peak, while the traditional 3 dB coupler can only get an AR valley with narrower bandwidth. Therefore, much wider AR bandwidths for different AR requirements are obtained by using the presented method. The wideband dual-feed antenna fed by these different couplers was simulated, fabricated, and measured for the final performance verification.

中文翻译：

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针对不同轴比要求的宽带双馈圆极化天线设计

针对不同的轴比 (AR) 要求，提出了一种设计宽带双馈圆极化 (CP) 天线的新方法。通过分析双馈CP天线馈电网络的输出特性，得到一个近似函数，并利用该函数计算在所需AR下馈电网络输出幅度和相位的方差。根据分析，不同的支线耦合器分别用于实现小于 3、2 和 1 dB 的宽 AR 带宽。与传统使用的 3 dB 耦合器相比，所提出的馈电方法可以在中心频率处有一个具有期望值的 AR 峰值和峰值旁边的两个 AR 谷，而传统的 3 dB 耦合器只能得到一个带宽更窄的 AR 谷。所以，通过使用所提出的方法，可以获得针对不同 AR 要求的更宽的 AR 带宽。对由这些不同耦合器馈电的宽带双馈天线进行了模拟、制造和测量，以进行最终性能验证。