RFI Mitigation of Radio Astronomical Receiver Using a Low-Profile Metasurface-Loaded Antenna

• Published in: IEEE transactions on electromagnetic compatibility Vol. 66; no. 1; pp. 108 - 117
• Main Authors: Chatterjee, Sougata, Gupta, Yashwant, Ghosh, Sambit Kumar, Bhattacharyya, Somak
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.02.2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antenna arrays; Antenna design; Antenna feeds; Antenna measurements; Antenna radiation patterns; Antennas; Aperture antennas; Apertures; Corrugated horn (CH) antenna; Dipoles; Equivalent circuits; filtering antenna; Filtration; Insertion loss; L-band; metasurface (MS); Metasurfaces; radio astronomy; Radio frequency interference; radio frequency interference (RFI); Radio signals; Receivers & amplifiers; Receiving antennas; Surface waves; Ultrahigh frequencies
• ISSN: 0018-9375; 1558-187X
• DOI: 10.1109/TEMC.2023.3331181

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.