Polarization-Insensitive, Highly-Selective Metasurface-Based Filtenna for Satcom Applications

Abstract

This paper presents a planar, polarization-insensitive, space-compatible, skirt-selective filtering transmitarray for satellite communications. The transmitarray employs a double-layer frequency selective surface (FSS) to enable filtering witha sharp roll-off factor. A novel hybrid square ring-modified split ring resonator (SRR) unit cell is introduced by arranging four SRRs in sequential rotation in a rectangular array. The SRRs are integrated with an internal strip and are inductively coupled to each other. Their design is optimized using both numerical techniques and a semi-analytical procedure based on equivalent circuit theory. The sequential rotation of the SRRs enables a stable wide-band response while maintaining a constant impedance to electromagnetic waves impinging on the FSS with either vertical or horizontal linear polarization. The selected unit cell shape allows for achieving a highly selective pass-band response with a significant rejection level and the synthesis of a narrow beam in an array configuration. A single FSS is capable of producing an effective filtering response on its own. This concept lends itself to a higher-order filteringconfiguration using a double-layer FSS. The double-layer FSS is designed to operate in Ku-Band (with a wideband 10 dB impedance bandwidth of 14.74 % (center frequency (fo) = 14.8 GHz), 3 dB transmission bandwidth of 19.1 % (fo = 14.9 GHz), and flat 0.2 dB transmission bandwidth of 11.7 % (fo = 14.74 GHz)), while displaying polarization insensitivity. The achieved roll-off is sharp and is larger than 29 dB/0.25 GHz across both the upper and lower passband edges. Furthermore, the antenna radiates a narrow broadside beam with half power beamwidth lower than 7-degrees and side lobe levels smaller than 12 dB at passband frequencies. Full-wave simulation results are presented and discussed