Abstract
The integration of the metasurface and antenna has brought new vitality to function integration and performance improvement for metasurfaces. In this study, we propose a radiation-scattering–integrated (RSI) design method of functional metasurfaces by incorporating antenna radiators into the substrates. The antenna radiators can also be considered as a band-stop frequency selective surface (FSS) embedded within the dielectric substrate, which adds up to the degree of freedom (DOF) in tailoring electromagnetic (EM) properties of the substrate. In this way, not only radiation function is added to the metasurfaces but also the original scattering-manipulation function is augmented. As an example, we apply this method to the design of a metasurface that can achieve a high radiation gain in-band and low-RCS out-of-band simultaneously. An antenna array was first designed, which uses circular patches as the radiators. Then, the antenna array was used as the substrate of a typical polarization conversion (PC) metasurface. The circular patch lies between the ground plane and the PC meta-atom, providing optimal electrical substrate thickness for PC at two separate bands. By adjusting structural parameters, the operating band of the antenna array can be made to lie in between the two PC bands. In this way, the metasurface can simultaneously possess high-gain radiation function in-band and high-efficiency PC function for RCS reduction out-of-band. A prototype was fabricated and measured. Both the simulated and measured results show that the metasurface can achieve satisfactory radiation gain in-band and significant RCS reduction out of band. This work provides an alternative method of designing multi-functional metasurfaces, which may find applications in smart skins and others.
Highlights
Metamaterials have undergone an unprecedented development since its birth
The previous section demonstrated that the desired polarization characteristic can be obtained by inserting the antenna radiator into the substrate and forming a new meta-atom
By inserting the antenna array into the dielectric substrate under the polarization conversion (PC) metasurface, the optimal electrical substrate thickness for PC at two separate bands is achieved simultaneously
Summary
Metamaterials have undergone an unprecedented development since its birth. Analogous to conventional materials consisting of molecules or atoms, metamaterials are usually composed of sub-wavelength dielectric or metallic resonators ( called meta-atoms) (Pendry, 2000; Smith et al, 2004; Cheng and Cui, 2006; Wang et al, 2010). The V-shaped structural elements with different response phases are arranged periodically according to the phase profile predicted by the theory so that the propagation direction of the electromagnetic wave can be freely controlled. Polarization, amplitude, and the phase of the electromagnetic (EM) waves can be controlled by designing the pattern of meta-atoms, adjusting the geometric parameters and loading resistor, etc. Antenna radiator structures are embedded within the substrate, which can be used as an antenna to radiate EM waves and exhibit band-stop properties This allows the electrical thickness of the substrate to vary with frequency, which can be tailored deliberately to achieve multiple functions at different bands. A dual-band PC metasurface with a co-polarization reflection “window” was designed by inserting a circular patch antenna into the substrate of a conventional PC meta-atom. This work provides an alternative way of designing multi-functional metasurfaces
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