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Xenos peckii vision inspires an ultrathin digital camera
摘要： Increased demand for compact devices leads to rapid development of miniaturized digital cameras. However, conventional camera modules contain multiple lenses along the optical axis to compensate for optical aberrations that introduce technical challenges in reducing the total thickness of the camera module. Here, we report an ultrathin digital camera inspired by the vision principle of Xenos peckii, an endoparasite of paper wasps. The male Xenos peckii has an unusual visual system that exhibits distinct benefits for high resolution and high sensitivity, unlike the compound eyes found in most insects and some crustaceans. The biologically inspired camera features a sandwiched configuration of concave microprisms, microlenses, and pinhole arrays on a flat image sensor. The camera shows a field-of-view (FOV) of 68 degrees with a diameter of 3.4 mm and a total track length of 1.4 mm. The biologically inspired camera offers a new opportunity for developing ultrathin cameras in medical, industrial, and military fields.
关键词： ultrathin digital camera,microlenses,biological inspiration,microprisms,Xenos peckii,pinhole arrays
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Compact Broadband Electronically Controllable SIW Phase Shifter for 5G Phased Array Antennas
摘要： This work presents a novel compact and broadband electronically controllable substrate integrated waveguide (SIW) phase shifter intended for beamsteering applications in antenna arrays for 5G wireless communication. The proposed phase shifter is designed to operate over a large bandwidth (26 GHz – 32 GHz) with a simulated maximum insertion loss of less than 3 dB and a maximum phase difference of more than 1000+50 over the entire band. The phase shift is provided via metal posts which are switched between capacitive and inductive loading through beam-lead PIN diodes.
关键词： 5G,antennas,Phase shifter,antenna arrays,SIW,millimeter wave
更新于2025-09-04 15:30:14
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Analysis and Design of High Frequency 1-D CMUT Imaging Arrays in Non-collapsed Mode
摘要： High frequency ultrasound imaging arrays are important for a broad range of applications, from small animal imaging to photoacoustics. CMUT arrays are particularly attractive for these applications as low noise receiver electronics can be integrated for an overall improved performance. In this paper we present a comprehensive analysis of high frequency CMUT arrays based on an experimentally verified CMUT array simulation tool. The results obtained on an example, a 40 MHz 1-D CMUT array for intravascular imaging, are used to obtain key design insights and tradeoffs for receive only and pulse-echo imaging. For the receiver side, thermal mechanical current noise, plane wave pressure sensitivity, and pressure noise spectrum are extracted from simulations. Using these parameters, we find that the receiver performance of CMUT arrays can be close to an ideal piston, independent of gap thickness and applied DC bias, when coupled to low noise electronics with arrays utilizing smaller membranes performing better. For pulse-echo imaging, thermal mechanical current noise limited SNR is observed to be dependent on the maximum available voltage and gap thickness. In terms of bandwidth, we find that Bragg resonance of the array, related to the fill factor, is a significant determinant of the high frequency limit and the fluid loaded single membrane resonance determines the lower limit. Based on these results, we present design guidelines requiring only fluid loaded single membrane simulations and membrane pitch to achieve a desired pulse-echo response. We also provide a design example and discuss limitations of the approach.
关键词： CMUT,Bragg’s resonance,CMUT design,High frequency arrays,Phased array,Photoacoustic receiver
更新于2025-09-04 15:30:14
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[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - Analog Beamforming based on Fourier Rotman Lens for Multibeam Applications
摘要： Spatial division represents a popular approach to increasing capacity in modern wireless networks. This paper presents a study of a simplified beamforming network based on a Fourier transform network with the number of output ports lower than the number of the elements in the antenna array. It is shown that connecting the output ports of Fourier transform network via power dividers to several array elements in phase, thus implementing a nearest-neighbor phase interpolation, preserves the gain and width of the beams in a narrow scanning sector. Therefore, in applications where few orthogonal beams are required to span a narrow spatial sector, the proposed approach can offer reduction of the hardware complexity. The simulated radiation patterns for a phase interpolation Fourier beamforming network are demonstrated. The antenna radiation patterns have been measured, using a Fourier Rotman lens with 2-way Wilkinson power dividers, which confirmed the simulated trends.
关键词： Rotman lens,beamforming,Fourier transform beamforming,Antenna arrays
更新于2025-09-04 15:30:14
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[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - Design and demonstration of Linearly-Polarized Transmit-Arrays in X-band
摘要： This paper describes the design and demonstration of planar transmit-arrays operating in X-band with 1-bit phase quantization and based on wideband high efficiency unit cells. The unit cell consists of two identical square patch antennas loaded by C-loop slots and interconnected in their centers by a metalized via hole. The proposed transmit-array achieves a maximum directivity of 25.1 dBi and a gain of 22.8 dBi. Radiation efficiency of 56.3% is also obtained with a 1-dB gain bandwidth of up to 9.2% around 9.85 GHz and very low cross-polarization levels. The beam-steering up to 30° is achieved by tilting the focal source.
关键词： Patch antenna,slot loaded patch,Transmit-array,Antenna arrays,X-band,Unit cell,beam-steering
更新于2025-09-04 15:30:14
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Fabrication of high fill-factor aspheric microlens array by dose-modulated lithography and low temperature thermal reflow
摘要： A cost-effective fabrication method for high quality and high fill-factor aspheric microlens arrays (MLAs) is developed. In this method, the complex shape of aspheric microlens is pre-modeled via dose modulation in a digital micromirror device (DMD) based maskless projection lithography system. Digital masks for several bottom layers are replaced from circle to hexagon for the purpose of enhancing the fill-factor of MLAs, then a low temperature thermal reflow process is conducted, after which the average surface roughness of microlens is improved to * 0.427 nm while the pre-modeled profile keeps unchanged. Experimental results show that the fabricated aspheric MLAs have almost 100% fill-factor, high shape accuracy and high surface quality. The presented method may provide a promising approach for rapidly fabricating high quality and high fill-factor aspheric microlens in a simple and low-cost way.
关键词： high fill-factor,dose-modulated lithography,aspheric microlens arrays,surface roughness,low temperature thermal reflow
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - The Stochastic Electromagnetic Theory of Antenna-Antenna Cross-Correlation in MIMO Systems
摘要： We develop a general stochastic electromagnetic theory of port antenna-antenna cross-correlation suitable for the analysis and design of MIMO systems. The frequency-domain theory starts with a stochastic illumination field carrying arbitrary statistics and interacting with generic antenna arrays. The cross-correlation expression was derived using the Antenna Current Green’s Function (ACGF) and is valid for any field type/statistics and for arbitrarily shaped antenna, including strong mutual coupling. It is shown that cross-correlation is distinct from mutual coupling and that the former can always be expressed as special product form involving pure antenna tensor and pure field-field cross-correlation, opening the door for new approaches to optimum MIMO system design.
关键词： the ACGF method,Cross-correlation,MIMO arrays
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - A Complex Low-RCS Antenna System for the Placement of mm-Wave Automotive Radars behind Car Bumpers
摘要： Automotive radars are one of the key sensor technologies to develop reliable fully-automated cars. They are usually installed behind the bumper of the vehicle and therefore, multiple reflections can occur. The multiple reflections can be mitigated with the use of low-RCS (radar cross-section) antenna arrays. This paper presents the design of a complex low-RCS multiple antenna system that mimics a typical MIMO (multiple-input multiple-output) configuration. A prototype has been developed and tested. Approximately 17 dB of RCS reduction has been experimentally achieved. The measurement results show that the use of such a low-RCS antenna system can successfully reduce the amplitude of multiple reflections.
关键词： radar antennas,microstrip antenna arrays,millimeter wave radar,radar cross-sections
更新于2025-09-04 15:30:14
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[IEEE 2018 15th International Multi-Conference on Systems, Signals & Devices (SSD) - Yassmine Hammamet, Tunisia (2018.3.19-2018.3.22)] 2018 15th International Multi-Conference on Systems, Signals & Devices (SSD) - FPA Based Design of 2?l Microstrip Antenna Array for CubeSat Communications
摘要： An important subsystem of a CubeSat is the communication module where microstrip patch antennas are mostly used. The antenna array presented in this paper is devoted to CubeSat communication systems. This paper includes a new approach based on flower pollination algorithm, FPA, for the antenna angular inset-feed and its depth as well as the antenna radius. The designed antenna is a 2x1 circular patch array operating in the S-band (2-4 GHz). Each element of the antenna was fed by the new angular-inset feed technique recently published. This original technique is more effective than conventional inset feed one and provide a more flexibility to improve the impedance matching of the system. The new FPA metaheuristic is used to optimize the performance of each circular patch in terms of return loss, gain and impedance. Here, this antenna array is fed by a compensated power divider having a good impedance matching. The antenna array was simulated by FEKO electromagnetic software. The return loss obtained near the ISM frequency of 2,45 GHz is -27.9663 dB and the simulated gain reached is 9.06 dB
关键词： FPA,Cube-sat,Microstrip antenna arrays,patch antennas,antenna design
更新于2025-09-04 15:30:14
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Wideband Dual-Polarized Multiple Beam-Forming Antenna Arrays
摘要： Wideband multi-beam antenna arrays based on three-beam Butler matrices are presented in this paper. The proposed beam-forming arrays are particularly suited to increasing the capacity of 4G long-term evolution (LTE) base stations. Although dual-polarized arrays are widely used in LTE base stations, analogue beam-forming arrays have not been realized before, due to the huge challenge of achieving wide operating bandwidth and stable array patterns. To tackle these problems, for the first time, we present a novel wideband multiple beam-forming antenna array based on Butler matrices. The described beam-forming networks produce three beams but the methods are applicable to larger networks. The essential part of the beam-forming array is a wideband three-beam Butler matrix, which comprises quadrature couplers and fixed wideband phase shifters. Wideband quadrature and phase shifters are developed using striplines, which provide the required power levels and phase differences at the outputs. To achieve the correct beamwidth and to obtain the required level of crossover between adjacent beams, beam-forming networks consisting of augmented three-beam Butler matrices using power dividers are presented to expand the number of output ports from three to five or six. Dual-polarized, three-beam antenna arrays with five and six elements covering LTE band are developed. Prototypes comprising beam-forming networks and arrays are tested according to LTE base station specification. The test results show close agreement with the simulation ones and compliance with LTE requirements. The designs presented are applicable to a wide range of wideband multi-beam arrays.
关键词： Butler matrix,quadrature couplers,dual-linear polarization,multi-beam,LTE base stations,wideband,beam-forming networks,phase shifters,Antenna arrays
更新于2025-09-04 15:30:14