A travelling-wave-fed slot spiral antenna with wide axial-ratio (AR) bandwidth and beamwidth for GNSS applications is proposed in this paper. The evolution procedure of the proposed antenna can be classified into three steps. Firstly, 12 identical spiral slots are arranged concentrically in a compact area, and AR roundness in low elevation plane is improved by virtue of good rotational symmetry of slot radiators. Secondly, a two-turn travelling-wave feed line is sequentially coupled to the slots, and wideband response of desired magnitude ratio and phase difference of $E_{\theta }$ and $E_{\varphi }$ is obtained by optimizing the number and growth rate of microstrip turns. Thirdly, by supporting the antenna with a modified metallic cavity, the CP radiation performance in low elevation plane is well improved, and thus a widened AR beamwidth is obtained. Finally, the proposed antenna with satisfactory performance is realized in a diameter of $0.56\lambda _{0}$ and height of $0.12\lambda _{0}$ , where $\lambda _{0}$ is the free-space wavelength at center frequency 1.4 GHz. Measured bandwidth of $|S_{11}|$ fully covers the entire GNSS bands, and the 3-dB AR bandwidth ranges from 1.14 to 1.67 GHz (37.7%). Moreover, the 3-dB AR beamwidth exceeds 140° at 1.4 GHz.

中文翻译：

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适用于 GNSS 应用的具有宽轴比带宽和波束宽度的行波馈送缝隙螺旋天线


本文提出了一种适用于 GNSS 应用的具有宽轴比 (AR) 带宽和波束宽度的行波馈电缝隙螺旋天线。所提出的天线的演进过程可以分为三个步骤。首先，12条相同的螺旋槽在紧凑的区域内同心排列，利用槽散热器良好的旋转对称性，提高了低仰面AR圆度。其次，将两匝行波馈线依次耦合到槽中，通过优化数量，得到$E_{\theta }$和$E_{\varphi }$所需幅值比和相位差的宽带响应。和微带匝数的增长率。第三，通过改进的金属腔体支撑天线，很好地改善了低仰角面的CP辐射性能，从而获得了加宽的AR波束宽度。最后，所提出的天线具有令人满意的性能，其直径为 $0.56\lambda _{0}$，高度为 $0.12\lambda _{0}$，其中 $\lambda _{0}$ 是自由空间波长中心频率1.4GHz。 $|S_{11}|$ 的测量带宽完全覆盖整个 GNSS 频段，3 dB AR 带宽范围为 1.14 至 1.67 GHz (37.7%)。此外，3dB AR 波束宽度在 1.4 GHz 时超过 140°。