A dual-wideband dual-polarized antenna using metasurface for the fifth generation (5G) millimeter wave (mm-wave) communications is proposed. It is designed and analyzed based on characteristic mode theory (CMT). The proposed metasurface is mainly composed of a 3×3 square-patch, in which its four corner patches are further sub-divided into a 4×4 sub-patch array, while the size of the other four edge patches is reduced and the center patch is etched with a pair of orthogonal slots. By doing so, the side lobe level can be effectively reduced and the main beam radiation can be enhanced. The metasurface is excited by a pair of orthogonally arranged substrate-integrated-waveguide (SIW) to grounded-coplanar-waveguide (GCPW) dual-polarized feeding networks that help to reduce the insertion loss and expand the frequency bandwidth of the feeding ports. In order to yield higher gain, four proposed metasurfaces are fed by a pair of 1-to-8-way power divider feeding networks including a pair of low-transmission-loss E-plane phase shifter. Measured results show desirable impedance bandwidths of 13.85% (24.2-27.8 GHz) and 14.81% (36.9-42.8 GHz) in the lower and upper frequency bands, respectively, and their corresponding average gains are 13.96 and 15.46 dBi.
INDEX TERMSDual-wideband, dual-polarized, high gain, 5G millimeter wave communications, characteristic mode theory.
Due to the difficulties and the limitations of traditional measurements, it is extremely challenging to obtain an accurate bond-slip relationship for a fiber-reinforced polymer (FRP) sheets to concrete interface. This paper presents experimental studies aimed at accurately measuring the bond-slip relationship of the FRP sheets to concrete interface using a digital image correlation (DIC) measurement. Double-lap shear specimens were tested with different layers and sequences of carbon or basalt FRP sheets attached to the concrete substrate. The fitting procedures for determining the bond-slip relationship from the DIC results were proposed and validated. The test results show that more comprehensive information during the debonding process can be recorded through the DIC measurement. Error reductions and more accurate bond-slip relationships can be achieved by using the fitting procedures. In addition, the type of FRP sheets and their sequence attached to the concrete surface have a significant influence on the bond behavior between FRP sheets and concrete substrate.
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