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Digital Holographic Display System with Large Screen Based on Viewing Window Movement for 3D Video Service
摘要： A holographic display system with a 22-inch LCD panel is developed to provide a wide viewing angle and large holographic 3D image. It is realized by steering a narrow viewing window resulting from a very large pixel pitch compared to the wave length of the laser light. Point light sources and a lens array make it possible to arbitrarily control the position of the viewing window for a moving observer. The holographic display provides both eyes of the observer with a holographic 3D image using two vertically placed LCD panels and a beam splitter to support the holographic stereogram.
关键词： Holographic display,large screen,3D video,wide angle,viewing window
更新于2025-09-10 09:29:36
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UWB Dual-polarized Dipole Array with Dielectric and FSS Superstrate and 65o Scanning
摘要： We report the design of an ultra‐wideband, dual‐polarized, tightly coupled dipole array (TCDA) with an integrated balun for wide angle scanning. A dual‐pol dipole design enables massive bandwidth, large scanning volume, and high polarization purity, concurrently. To achieve wide angle impedance matching without exciting surface waves, two types of superstrates are evaluated on a finite array: 1) dielectric superstrate and 2) novel planar frequency selective surface (FSS). The latter architecture is capable of scanning 70° in E Plane and 65° in H Plane and shows, on average, 5° scanning improvement to the former. The impedance bandwidth is 5.25:1 (0.8‐4.2 GHz) at the broadside (VSWR<2). The bandwidth reduces to 4.3:1 (0.9‐3.9 GHz) when maximum scanning angle or θmax increases to 65° for the H plane and 70° for the E plane (VSWR < 3.2). The proposed array is a great candidate for wide‐angle wide‐band scanning applications covering the entire L and S bands.
关键词： dielectric superstrate,FSS,wide angle scanning,TCDA,Ultra-wideband,frequency selective surface,dual-polarized,tightly coupled dipole array,integrated balun
更新于2025-09-10 09:29:36
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Polarization controllable and wide-angle frequency tunable metamaterial absorber
摘要： In this paper, the design, fabrication, and measurement of a high-performance metamaterial absorber (MMA) have been presented. The three major concerns of MMA’s are narrow bandwidth, angle sensitivity, and uncontrollable polarization. By smartly controlling the proposed design, the solutions to these three concerns of MMA are given in this paper. By integrating the design with varactor diodes, we make the MMA tunable to wide frequency ranges. Frequency tunability ranges from 4.2 to 7 GHz. By using circular sectors in the resonator, wide incident angle insensitivity has been achieved. The presented MMA exhibits more than 80% absorptivity up to 70° incident angles. With the proposed design, it is possible to control either TM or TE polarization resonant frequency by ?xing the resonant frequency of other polarization. Also, a biasing technique which is simple and effective to control both TM and TE resonant frequencies simultaneously is given in this paper. Moreover, all these advantages have been achieved by using a single layer low cost FR4 material having thickness 0.6 mm as a substrate. By using a standard parameter retrieval technique, the real and imaginary parts of both permittivity and permeability of the presented MMA are calculated. It is expected that the presented work improves the state-of-the-art in the smart metamaterial absorber domain.
关键词： varactor diodes,metamaterial absorber,polarization controllable,wide-angle frequency tunable,FR4 material
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu, China (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Design of Wideband and Wide-Angle Scanning Phased Array Based on Wideband EBG Structure
摘要： A linear dipole array based on wideband electromagnetic bandgap (EBG) is designed in this paper. The linear array is organized along the H plane and the simulated results of an infinite array show that it features a bandwidth of 24.1% (from 5.1 to 6.5GHz) while scanning to 70° in the H plane with VSWR<2.5. Then, a 1×20 finite linear dipole array based on the above element configuration is designed. The array has the ability to scan up to 75° with a gain reduction less than 3 dB at 5GHz, and scan up to 80° with a gain reduction less than 3 dB at 5.7GHz, and scan up to 88° with a gain reduction about 4 dB at 6.1GHz.
关键词： wide-angle scanning,phased array,wideband,electromagnetic bandgap
更新于2025-09-09 09:28:46
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Development of an Automated Screening System for Retinopathy of Prematurity Using a Deep Neural Network for Wide-angle Retinal Images
摘要： Background: Retinopathy of prematurity (ROP) is one of the main causes of childhood blindness. However, insufficient ophthalmologists are qualified for ROP screening. Objective: To evaluate the performance of a deep neural network (DNN) for automated screening of ROP. Methods: The training and test sets came from 420,365 wide-angle retina images from ROP screening. A transfer learning scheme was designed to train the DNN classifier. First, a pre-processing classifier images. Then, pediatric ophthalmologists labeled each image as either ROP or negative. The labeled training set (8090 positive images and 9711 negative ones) was used to fine-tune three candidate DNN classifiers (AlexNet, VGG-16, and GoogLeNet) with the transfer learning approach. The resultant classifiers were evaluated on a test data set of 1742 samples, and compared with five independent pediatric retinal ophthalmologists. The ROC (receiver operating characteristic) curve, ROC area under the curve (AUC) and P-R (precision-recall) curve on the test data set were analyzed. Accuracy, precision, sensitivity (recall), specificity, F1 score, Youden index, and MCC (Matthews correlation coefficient) were evaluated at different sensitivity cutoffs. The data from the five pediatric ophthalmologists were plotted in the ROC and P-R curves to visualize their performances. Results: VGG-16 achieved the best performance. At the cutoff point that maximized F1 score in the precision-recall curve, the final DNN model achieved 98.8% accuracy, 94.1% sensitivity, 99.3% specificity, and 93.0% precision. This was comparable to the pediatric ophthalmologists (98.8% accuracy, 93.5% sensitivity, 99.5% specificity and 96.7% precision). Conclusion: In the screening of ROP using the evaluation of wide-angel retinal images, DNNs had high accuracy, sensitivity, specificity, and precision, comparable to that of pediatric ophthalmologists.
关键词： image classification,retinopathy of prematurity,transfer learning,deep neural network,wide-angle retinal image,computer-aided diagnosis
更新于2025-09-09 09:28:46
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Wide-Angle Beam Scanning Leaky-Wave Antenna Using Spoof Surface Plasmon Polaritons Structure
摘要： This paper proposes a wide-angle beam scanning leaky-wave antenna (LWA) fed by a novel spoof surface plasmon polaritons (SSPP) transmission line (TL). In the proposed LWA, circular metallic patches are periodically loaded on both sides of the SSPP TL alternately, and convert guided waves into radiating waves. The transmission characteristics of the proposed SSPP TL are analyzed, and the transmission characteristics and radiation patterns of the proposed LWA are simulated and measured. The simulated and measured results show that the proposed LWA provides approximately 12.5 dBi of radiation gain within a frequency range of 8–24 GHz, and a beam scanning range of 90? from forward to backward continuously by increasing the feeding frequency. The proposed LWA, based on a novel SSPP TL, has advantages of single-layer conductor, continuous wide-angle beam scanning, and high gain especially at the broadside direction, which are dif?cult realize using conventional LWAs.
关键词： beam scanning,spoof surface plasmon polaritons (SSPP),wide-angle,leaky-wave antenna (LWA)
更新于2025-09-09 09:28:46
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A WIDEBAND WIDE-ANGLE ULTRA-THIN METAMATERIAL MICROWAVE ABSORBER
摘要： A novel design of wideband, ultra-thin, wide-angle metamaterial microwave absorber has been presented. The unit cell of the proposed structure is designed by using parametric optimization in such a way that absorption frequencies come closer and give wideband response. For normal incidence, the simulated FWHM bandwidth of the proposed structure is 1.94 GHz, i.e., from 5.05 GHz to 6.99 GHz and ?10 dB absorption bandwidth is 1.3 GHz from 5.27 GHz to 6.57 GHz. The proposed structure has been analyzed for di?erent angles of polarization, and it gives high absorption (more than 50%) for oblique angles of incidence up to 60?. The designed absorber is in low pro?le with a unit cell size of λ0/6 and ultrathin with a thickness of λ0/32 at the center frequency of 5.92 GHz corresponding to 10dB absorption bandwidth. The current and electromagnetic ?eld distributions have been analyzed to understand the absorption mechanism of the absorber. An array of the proposed absorber has been fabricated and experimentally tested for various polarization angles and oblique incidences of electromagnetic wave. The proposed absorber is well suited for surveillance and other defense applications.
关键词： wideband,metamaterial,wide-angle,microwave absorber,ultra-thin
更新于2025-09-04 15:30:14
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Polarization-insensitive and wide-angle broadband absorption enhancement of molybdenum disulfide in visible regime
摘要： In order to remarkably enhance the absorption capability of monolayer molybdenum disulfide (MoS2), a broadband MoS2-based perfect absorber, which is inspired by metamaterial, is proposed. By using the finite-difference time-domain (FDTD) simulations, the absorption of proposed MoS2-based absorber above 94% is achieved from 594 to 809 nm. Meanwhile, the average absorptions of monolayer MoS2 enhanced up to 27% and 67% are realized from 598 to 671 nm and 710 to 801 nm, respectively. By manipulating related structural parameters, the absorption spectrum can be further broadened and shifted in a wide wavelength range. Furthermore, the proposed absorber can tolerate a relatively wide range of incident angles and demonstrate polarization-independence.
关键词： metamaterial,polarization-insensitive,wide-angle,broadband absorber,MoS2
更新于2025-09-04 15:30:14