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This paper presents a miniaturized ultra-wideband (UWB) antipodal Vivaldi antenna (AVA) array with low-scattering characteristics integrated a hybrid diffusive-absorptive metasurface. Periodic elliptical slots at the outer edges and a dielectric lens are utilized for antenna element to improve performances including miniaturized size, wide bandwidth, and high gain. The optimized element is fabricated and measured, the results demonstrate that the − 10 dB impedance bandwidth is 4.5–50 GHz with a ratio bandwidth (fH/fL) of 11.1:1, and the maximum gain at 35 GHz is 12.7 dBi, which are in good agreement with simulation. By loading an optimized Minkowski-shaped metasurface as the ground reflector, which combines the multielement phase cancellation (MEPC) and EM absorption technology, the 4 × 4 array realizes a low radar cross section (RCS) without the radiation performance degradation. Simulated and measured results show that the proposed low-scattering array has a 10-dB RCS reduction band ranging from 5 to 50 GHz at normal incidence for both polarizations. Furthermore, the array structure shows extremely low-observable capability, which is larger than 15 dB of the RCS reduction from 7.1 to 50 GHz with a ratio bandwidth of 7.0:1. The results verify the feasibility of improving the performance of antenna and the UWB low-scattering functionality. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymer (CFRP) materials are important reinforcing substances which are widely used in the shear strengthening of seismic-damage steel reinforced concrete (SRC) frame structures. To investigate the shear strength of SRC frame columns strengthened with CFRP sheets, experimental observations on eight seismic-damaged SRC frame columns strengthened with CFRP sheets were conducted at Yangtze University and existing experimental data of 49 SRC columns are presented. Based on the existing experiments, the theories of damage degree, zoning analysis of concrete, and strengthening material of the column are adopted. To present the expression formula of the shear strength of SRC frame columns strengthened with CFRP sheets, the contributions of strengthening material and transverse reinforcement to shear strength in the truss model are considered, based on the truss-arch model. The contribution of arch action is also considered through the analysis of the whole concrete and that of the three zones of the concrete are also considered. The formula is verified, and the calculated results are found to match well with the experimental results. Results indicate that the proposed whole analysis model can improve the accuracy of shear strength predictions of shear seismic-damaged SRC frame columns reinforced with CFRP sheets. [ABSTRACT FROM AUTHOR]