Ultrawide-Angle Broadband Electromagnetic Window for Both TM- and TE-Polarizations by Synergy of Multimechanism Resonances

Abstract

As protective apparatus, electromagnetic windows (EMWs) are usually realized utilizing dielectric materials with higher permittivity or larger thickness to perform good mechanical properties. However, due to impedance mismatch, higher insertion loss is inevitably created, especially at large incident angles. It is now still a great challenge to engineer EMWs with stable operating bands and a wide range of incident angles for both transverse electric (TE)-and transverse magnetic (TM)-polarizations. In this article, we propose a method to achieve such EMWs by the synergy of multimechanism resonances, which enables broadband transmissions of both TM-and TE-polarized waves in an ultrawide range of incident angles. Fano resonance is first introduced to expand the bandwidth for TE-polarization on the basis of thickness resonance. Drude resonances are then introduced to suppress adverse influences of the parasitic Lorentz resonance for TM-polarization, to maximize the shared transmission band for TM-and TE-polarizations. The ultrawide-angle broadband functionalities of this EMW are validated by experiments, which agree well with numerical simulations. This work provides an efficient route to realize practical high-performance EMWs, under sufficient consideration of available materials, structures, and fabrication techniques, which may find wide applications in radar, communication, and imaging systems.