Browsing by Author "Ye, Dexin"
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Item Compensating group delay distortion of signals based on engineered material dispersion(2017) Wang, Chun; Zhu, Zhongbo; Cao, Cheng; Qiao, Shan; Li, Changzhi (TTU); Ye, DexinDispersion, which originates from the total frequency responses of materials, devices and transmission lines, makes envelope distortion of signals inevitable in transmission systems. In this study, we investigate the group delay distortion of a signal due to the presence of dispersion in transmission systems, and propose an approach to eliminate the distortion by compensation based on engineered material dispersion. We demonstrate theoretically and experimentally that utilizing the anomalous frequency response of a dispersive material, envelope distortion of a signal passing through a given transmission system can be fully compensated. Compared with previous researches on dispersion compensation using grating compressors or chirp compressors in optics and non-Foster circuits in microwave bands, the proposed approach is robust and scalable to other frequency bands.Item Microwave Imaging under Oblique Illumination(2016) Meng, Qingyang; Xu, Kuiwen; Shen, Fazhong; Zhang, Bin; Ye, Dexin; Huangfu, Jiangtao; Li, Changzhi (TTU); Ran, LixinMicrowave imaging based on inverse scattering problem has been attracting many interests in the microwave society. Among some major technical challenges, the ill-posed, multi-dimensional inversion algorithm and the complicated measurement setup are critical ones that prevent it from practical applications. In this paper, we experimentally investigate the performance of the subspace-based optimization method (SOM) for two-dimensional objects when it was applied to a setup designed for oblique incidence. Analytical, simulation, and experimental results show that, for 2D objects, neglecting the cross-polarization scattering will not cause a notable loss of information. Our method can be potentially used in practical imaging applications for 2D-like objects, such as human limbs.Item Wide-Angle Beam Steering Based on an Active Conformal Metasurface Lens(2019) Li, Huan; Ma, Chao; Shen, Fazhong; Xu, Kuiwen; Ye, Dexin; Huangfu, Jiangtao; Li, Changzhi (TTU); Ran, Lixin; Denidni, Tayeb A.This work experimentally demonstrates a wide-angle beam steering based on an active conformal metasurface lens. Integrated with microwave varactors, the transmission phase of this cylindrical metasurface lens can be tuned in a range up to 195° by direct-current (DC) bias voltages. By compensating the phase difference between different incidences, the proposed cylindrical lens can collimate the incident spherical wave front into a plane wave front with predefined deflection angle. By increasing the number of feeding sources, the beam steering range of conformal lens can be expanded to ±60°. Having advantages of low cost and simple structure, the proposed conformal lens can be extended to millimeter-wave band and enable a wide range of applications.