Tunable microwave metasurfaces for high-performance operations: dispersion compensation and dynamical switch

Abstract

Controlling the phase distributions on metasurfaces leads to fascinating effects such as anomalous light refraction/reflection, flat-lens focusing, and optics-vortex generation. However, metasurfaces realized so far largely reply on passive resonant meta-atoms, whose intrinsic dispersions limit such passive meta-devices’ performances at frequencies other than the target one. Here, based on tunable meta-atoms with varactor diodes involved, we establish a scheme to resolve these issues for microwave metasurfaces, in which the dispersive response of each meta-atom is precisely controlled by an external voltage imparted on the diode. We experimentally demonstrate two effects utilizing our scheme. First, we show that a tunable gradient metasurface exhibits single-mode high-efficiency operation within a wide frequency band, while its passive counterpart only works at a single frequency but exhibits deteriorated performances at other frequencies. Second, we demonstrate that the functionality of our metasurface can be dynamically switched from a specular reflector to a surface-wave convertor. Our approach paves the road to achieve dispersion-corrected and switchable manipulations of electromagnetic waves.

Miniaturized frequency reconfigurable pentagonal MIMO slot antenna for interweave CR applications

“…For the proposed antenna design, ECC values computed between all antenna elements were below the threshold value of 0.5 . Further, the isolation between antenna elements is at least 10 dB, which is adequate for a MIMO design . The ECC values are summarized in Table .…”

“…The board dimensions were 46 × 20 × 1.6 mm 3 . Some state of the art tunable technique are reported in References . In Reference , a technique based on tunable meta‐atoms with reverse bias varactor diodes resolve the issues of microwave metasurfaces.…”

“…Some state of the art tunable technique are reported in References . In Reference , a technique based on tunable meta‐atoms with reverse bias varactor diodes resolve the issues of microwave metasurfaces. The dispersive response of each meta‐atom is precisely controlled by an external voltage applied to the diode.…”

Beam-reconfigurable crescent array antenna with AMC plane

“…A popular switching technique to realize the pattern reconfigurability is through the integration of the PIN diodes . Despite this, the antenna's efficiency and gain typically degrades due to the passive nature of the PIN diodes .…”

Radar cross section reduction metasurfaces based on phase gradient and chessboard structure

“…Metasurface (MS) is a kind of artificial materials that can be used to control the reflection/transmission EM waves with different resonant frequency, phase, and polarization. Many different kinds of MSs have been proposed to reduce RCS, such as the perfect MS absorbers, the artificial magnetic conductor chessboard structure, phase random metasurface (PRM), and phase gradient metasurface (PGM) . In 2017, a wideband RCS reduction based on the chessboard polarization conversion MS was proposed whose phase differences were preserved as 180° ± 37° .…”