Broadband metasurface bandpass filter with wide angular stability for the Ku-band

Abstract

Broadband spatial spectral filters have consistently been in high demand due to their diverse and extensive applications across numerous fields in the past decades. In this paper, a broadband metasurface (MS) bandpass filter (BPF) with wide angular stability was proposed and investigated at Ku band. The unit-cell of the proposed MS BPF is consisted of the cross-shape structure (CSS) sandwiched with two layer identical four-square-patches (FSPs) and dielectric substrates. Finite element method (FEM) simulation indicates that the designed MS BPF has distinctive broadband transmission coefficient of over −3 dB from 12.75 GHz to 16.8 GHz with a relative bandwidth of 27.4 %, which is basically consistent with equivalent circuit model (ECM) calculation. The physical mechanism underlying the proposed MS BPF is elucidated through the introduction of impedance matching theory, electric field and surface current analysis. Further numerical simulation has confirmed that the designed broadband MS BPF exhibits valid performance across a wide spectrum of incident angles, encompassing both transverse electric (TE) and transverse magnetic (TM) polarizations. Finally, a prototype has been fabricated for measurements, and the proposed design has been validated through comprehensive analysis of simulated and measured results. Due to its excellent transmission properties, the proposed MS BPF shows potential application in such as radar, remote sensing, and satellite communication.