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These unique properties were applied to significantly extending functionalities of conventional devices and systems(e.g. in antennas4,5 and absorbers6–10) or developing new kinds of electromagnetic applications (e.g. cloakingdevices11–13, superlenses14,15 and wavefront conversion16–18). Additionally, designing these artificial structureswith nonlinear media or nonlinear circuits gave us an additional degree of freedom to control electromagneticproperties19–22. Especially, metasurfaces were recently designed with several circuit elements including schottkydiodes so that they enabled us to sense difference in the waveforms of incoming waves or pulse widths23–25 (Fig. 1).This new capability to distinguish different waves even at the same frequency was expected to give us anotherdegree of freedom to control electromagnetic waves, thereby leading to development of new kinds of microwavedevices and applications such as waveform-selective wireless communications26. However, all the past studies wereevaluated with only surface waves or free-space waves at a normal angle23,24,27, although in reality electromagneticwaves scatter from various structures or boundaries and therefore illuminate such metasurfaces at obliqueangles. For this reason we clarify angular dependences of waveform-selective metasurfaces both numericallyand experimentally. Especially, this study focuses on two types of waveform-selective metasurfaces, specifically,capacitor-based waveform-selective metasurfaces and inductor-based waveform-selective metasurfaces, each ofwhich more effectively absorbs short pulses and long pulses, respectively, at the same frequency26. This performanceremains unchanged for a wide range of incident angle but becomes reduced for a large incident angle, whichis also discussed to improve in this study. Our results demonstrated here are expected to open up possibilities toapply the waveform selectivity for a wider range of electromagnetic applications even with angled waves.
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