In this article, a low profile metasurface (MS)–based antenna design has been proposed, which can be easily mounted inside an aperture antenna [corrugated horn (CH) feed] to stop the unwanted radio frequency interference (RFI) signals, thereby leading toward the improvement of the sensitivity in the front-end receiver in radio astronomical measurements without affecting its dynamic range. The meta-atom of the MS consists of an orthogonal dipole resonator designed on the top surface of an FR4 dielectric with 0.8 mm thickness, whereas the backside of the dielectric comprises two concentric circular rings with a fourfold symmetry, making the structure polarization insensitive in nature. The bandpass feature of the MS is realized between 1.1 and 1.4 GHz, which has been simultaneously validated by developing an equivalent circuit model and experimental characterization. The MS has thereafter been loaded within an L-band CH antenna to constitute the complete module of the filtering antenna operating between 1.13 and 1.53 GHz. The radiation patterns of the filtering antenna and the aperture antenna are identical in the passband maintaining an extremely low insertion loss of 0.3 dB while there is more than 20 dB reduction in the stopband. The as-proposed filtering antenna has been deployed for the open sky test in an L-band radio astronomical receiver. It has been observed that the signal at 1.42 GHz corresponding to the neutral hydrogen emission line can be properly detected by the filtering antenna by mitigating the strong RFI lines at 0.95 GHz and 1.8 GHz by 12 dB and 21 dB, respectively, thereby allowing the subsequent blocks of the receiver system to work in the linear region.

中文翻译：

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使用薄型超表面负载天线减轻射电天文接收器的 RFI

在本文中，提出了一种基于薄型超表面（MS）的天线设计，它可以轻松安装在孔径天线[波纹喇叭（CH）馈源]内部，以阻止不需要的射频干扰（RFI）信号，从而导致在不影响其动态范围的情况下提高射电天文测量中前端接收器的灵敏度。MS的元原子由设计在0.8毫米厚的FR4电介质顶面上的正交偶极子谐振器组成，而电介质的背面包括两个具有四重对称性的同心圆环，使得该结构本质上对偏振不敏感。MS 的带通特性在 1.1 至 1.4 GHz 之间实现，并通过开发等效电路模型和实验表征同时得到验证。此后，MS 被加载到 L 波段 CH 天线中，以构成工作在 1.13 至 1.53 GHz 之间的滤波天线的完整模块。滤波天线和孔径天线的辐射方向图在通带内相同，保持 0.3 dB 的极低插入损耗，同时在阻带内减少 20 dB 以上。所提出的滤波天线已部署在 L 波段射电天文接收机中进行开放天空测试。据观察，通过将 0.95 GHz 和 1.8 GHz 的强 RFI 线分别减轻 12 dB 和 21 dB，滤波天线可以正确检测到对应于中性氢发射线的 1.42 GHz 信号，从而允许后续检测。接收器系统的模块工作在线性区域。