A Dual-Functional Frequency-Selective Polarization Converting Metasurface With Reduced Backward-Scattering Characteristics

Abstract

A novel dual-functional frequency-selective metasurface (MS) with low backscattering is proposed by integrating a reflective cross-polarization (LRCP) converter with a bandpass frequency-selective surface (BP-FSS). The proposed MS comprises three layers, with a cross-dipole FSS in the middle layer that provides high-efficiency bandpass transmission. The thickness, inter-gap, and interlayer spacing of the diagonally oriented metallic strip gratings (MSGs), printed on the top and bottom layers, are meticulously optimized to achieve efficient LRCP conversion while maintaining high transmittance transparency for the out-of-band frequencies. The proposed MS simultaneously exhibits two independent functionalities: co-polarized bandpass transmission from 3.74 to 5.12 GHz with a simulated insertion loss of above -1 dB, and LRCP conversion from 5.72 to 7.33 GHz with a polarization conversion ratio (PCR) exceeding 0.99. The design concept is validated using two equivalent circuit models (ECMs) corresponding to the BP-FSS and the cascaded MS configuration, as well as through measurements of the fabricated prototype comprising 16× 16 unit-cell arrays arranged in a chessboard configuration. Both the ECM predictions and measurements show good alignment with the full-wave simulation findings. In addition, the measurement results showcase significant radar cross-section (RCS) reduction across the frequency range from 5.94 - 7.21 GHz. Unlike conventional LRCP-MSs, the proposed work eliminates the need for a complete ground plane, and hence, its dual functionality makes it a promising candidate for Radome and communication platforms.