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DIFFRACTION-LIMITED IN-PHASE-MODE OPERATION FROM uniform array OF ANTIGUIDES WITH ENHANCED INTERELEMENT LOSS

ELECTRONICS LETTERS 1989年第19期25卷 1282-1283页

作者： BOTEZ, D HAYASHIDA, P MAWST, LJ ROTH, TJ PETERSON, G TRW Space & Technol. Group Rendondo Beach CA USA

Out-of-phase-mode oscillation is suppressed in a nearly resonant array of antiguides by introducing high transverse radiation losses ( approximately=150 cm-1) in the interelement regions. Ten-element devices operate in the in-phase array mode, diffraction-limited up to 2.5*threshold, and with lobe widths of 1.6*diffraction limit at 4*threshold (230 mW total power).

关键词： 230 mW GaAs-AlGaAs antiguides diffraction limited beam high transverse radiation losses in-phase-mode operation integrated optics integrated optics interelement loss interelement regions laser modes nearly resonant array optical losses optical waveguides out of phase mode oscillation suppression semiconductor junction lasers semiconductor lasers uniform array

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Inverse Beam Pattern Transform and Spatial Sampling for uniform array From Broadband Beamforming Perspective

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2022年 70卷 2431-2442页

作者： Le Son, Phan Tech Univ Kaiserslautern Digitale Signalverarbeitung Elektrotech & Infor M D-67663 Kaiserslautern Germany

A sensor array collects spatial samples of propagating wave fields, and a beamformer performs spatial filtering to preserve the desired signal while suppressing interfering signals and noise arriving from directions other than the direction of interest. Given a signal with wideband frequency, using a uniform array is one of the most common approaches to obtain broadband beamforming. In this work, a function formulating the relations between the sensor coefficients and its beam pattern over frequency is introduced. The function is called inverse beam pattern transform. The inverse beam pattern transform mainly contains the coordinate transform and inverse Fourier transform. From the view of spatial aliasing, the inter-distance of the sensors should be less than half of the minimum wavelength of the signal. However, from the bijection of the new function and broadband beamforming perspective, this paper proposes the other lower and upper bounds for the inter-distance. Within these bounds, the new function is the bijective function which can be applied to design the uniform array with broadband beamforming.

关键词： array signal processing Structural beams Sensor arrays Broadband communication Fourier transforms Frequency synthesizers Planar arrays Beamforming spatial sampling uniform array

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Frequency and 2D angle estimation based on a sparse uniform array of electromagnetic vector sensors

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EURASIP JOURNAL ON APPLIED SIGNAL PROCESSING 2006年第1期2006卷 080720-080720页

作者： Ji, Fei Kwong, Sam S China Univ Technol Sch Elect & Informat Engn Guangzhou 510640 Peoples R China City Univ Hong Kong Dept Comp Sci Kowloon Hong Kong Peoples R China

We present an ESPRIT-based algorithm that yields extended-aperture two-dimensional ( 2D) arrival angle and carrier frequency estimates with a sparse uniform array of electromagnetic vector sensors. The ESPRIT-based frequency estimates are first achieved by using the temporal invariance structure out of the two time-delayed sets of data collected from vector sensor array. Each incident source's coarse direction of arrival (DOA) estimation is then obtained through the Poynting vector estimates ( using a vector cross-product estimator). The frequency and coarse angle estimate results are used jointly to disambiguate the cyclic phase ambiguities in ESPRIT's eigenvalues when the intervector sensor spacing exceeds a half wavelength. Monte Carlo simulation results verified the e. ectiveness of the proposed method. Copyright (C) 2006 Hindawi Publishing Corporation. All rights reserved.

关键词： uniform array Dataset phase ambiguity Cloning Vectors Angle of arrival Angle Sensors CARRIER FREQUENCY Direction of arrival estimation ELECTROMAGNETIC Yield

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Comparisons between 2D and 3D uniform array Antennas

Comparisons between 2D and 3D Uniform Array Antennas

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Federated Conference on Computer Science and Information Systems

作者： Andy Vesa Florin Alexa Horia Balta POLITEHNICA University Communications Department

ISBN: (纸本)9781479967476

For any wireless communications antenna system becomes indispensable. In this paper we analyzed linear array, planar array and three - dimensional (3D) array antennas. The array systems are simulated in Matlab based on uniform linear array antennas. Comparisons between planar array antenna and 3D array antenna are provided take into account different phases of currents injected in antenna elements. Also we propose to use the array antenna in WSN due to the advantages in signal to noise ratio and power consumption.

关键词： Antenna arrays ANTENNA three-dimensional array planar antenna arrays uniform array antenna element signal to noise ratios MATLAB Phase current Wireless sensor networks WSN gene Power consumption ocean currents water currents currents

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A Fast and Novel Method of Pattern Synthesis for Non-uniform Phased array Antennas 16

A Fast and Novel Method of Pattern Synthesis for Non-Uniform...

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16th International Radar Symposium (IRS)

作者： Tohidi, Ehsan Sebt, Mohammad A. Nayebi, Mohammad M. Behroozi, Hamid Sharif Univ Technol Tehran Iran KN Toosi Univ Technol Tehran Iran

ISBN: (纸本)9783954048533

Weighting elements to achieve radiation patterns with desired characteristics is a classical work in phased array antennas. These characteristics can be low sidelobe level, narrow beamwidth, high directivity, pattern nulling in special angle and etc. For each of these characteristics, different methods have been introduced. Most of methods have been presented for uniform arrays, however there are lots of methods to obtain a desired pattern for antennas with non-uniform element distances. The problem with these methods is complexity or not very good results. In this paper, fast and easy methods based on Least Square Error that leads to good results are presented. In addition, weighting of thinned arrays as a special case of non-uniform arrays is studied here. Mono-pulse pattern synthesis (most important method of angular positioning) in thinned arrays employing the presented method is the other aim of this paper. Simulation results represent performance of developed algorithm.

关键词： pattern synthesis antenna phased arrays uniform array Antenna arrays Radiation patterns ANTENNA

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A Fast and Novel Method of Pattern Synthesis for Non-uniform Phased array Antennas

A Fast and Novel Method of Pattern Synthesis for Non-Uniform...

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International Radar Symposium

作者： Ehsan Tohidi Mohammad A. Sebt Mohammad M. Nayebi Hamid Behroozi Sharif University of Technology K. N. Toosi University of Technology

ISBN: (纸本)9781479978410

关键词： pattern synthesis antenna phased arrays uniform array Radiation patterns ANTENNA

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Sub-array Design Diagnostics for the Development of Large uniform arrays

Sub-array Design Diagnostics for the Development of Large Un...

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2011 IEEE International Symposium on Antennas and Propagation(APSURSI 2011)

作者： Timothy Brockett Yahya Rahmat-Samii Electrical Engineering Department University of California Los Angeles Los Angeles CA USA

ISBN: (纸本)9781424495627;9781424495634

The use of sub-arrays has been a popular approach in the design of large array antennas. Using sub-arrays simplifies the array design by allowing the designer to concentrate on the smaller sub-array and repeating it throughout the rest of the array. Anomalous grating lobes have been shown to appear in large uniform arrays caused by systematic errors in the design of sub-array. Thus, it is important for the sub-array designer to be able to diagnose errors in the sub-array design before incorporating it into the larger array. This paper will categorize and demonstrate specific sub-array pattern distortions that can cause grating lobes to appear in uniform arrays. In addition, a design example will present how recognition of the aforementioned distortions can be used to diagnose and prevent the appearance of grating lobes. This will be done by showing the design process of a 1X16 linear array design that uses four 1X4 sub-arrays. Its design progress will include analytical, full-wave simulation, and measurement parts.

关键词： array antennas design diagnostics grating lobes sub-arrays subarray uniform array grating lobe design error design schedule Antenna arrays

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uniform arrayS OF RESONANT-CAVITY ENHANCED INGAAS-ALGAAS HETEROJUNCTION PHOTOTRANSISTORS

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IEEE PHOTONICS TECHNOLOGY LETTERS 1995年第6期7卷 682-684页

作者： SJOLUND, O LARSSON, A Department of Optoelectronics and Electrical Measurements Chalmers University of Technology Goteborg Sweden

We present uniformity data on arrays of resonant cavity enhanced InGaAs-AlGaAs phototransistors responding to wavelengths for which the GaAs substrate is transparent The arrays consist of 7x7 transistors. The uniformity in resonant wavelength and maximum responsivity was found to be good within individual arrays, The standard deviation of the resonant wavelength was significantly smaller than the resonance full width at half maximum of 8 nm, However, large variations were observed between arrays. This shows the need for a resonant transistor design that can be post-growth tuned to the desired resonance wavelength without affecting the maximum responsivity.

关键词： Transistor Device Component arrays uniform array resonant cavities Heterojunctions Phototransistor Device Component resonant wavelength wavelengths

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Simulation and design of T-shaped barrier tops including periodic split ring resonator arrays for increased noise reduction

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APPLIED ACOUSTICS 2025年 236卷

作者： Qin, Xiaochun Yang, Weijie Zhang, Zijian Wangari, Vicky Wangechi Beijing Jiaotong Univ Sch Civil Engn Beijing 100044 Peoples R China

Road traffic flows are increasing and so are associated noise levels along highways. Simply increasing the height of conventional noise barriers is not a sustainable way of meeting the greater requirements for noise control. This paper reports the design of two types of structures involving either horizontal or vertical cylindrical split ring resonators placed on a T-shaped noise barrier to improve its acoustical performance. These structures exploit mechanisms of Bragg scattering, cavity resonance, and sound absorption by cylindrical microperforated plate inserts. The designs are based on 2D and 3D finite element models and measured frequency spectra of highway noise. They have been validated by full scale tests in a semi-anechoic laboratory. The structures with uniformly reducing numbers of horizontal resonators in successive rows and uniformly reducing heights in successive rows of vertical resonators are found to offer the best overall noise reduction. Microperforated cylindrical inserts are found to increase the reduction offered by the horizontal resonator arrangements by 5 dB near 2 kHz, while having little effect on the performance of the arrays of vertical resonators.

关键词： Noise barrier uniform array Traffic noise Micro-perforated plate

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Analysis of uniform arrays of three-dimensional unequal-depth cracks in a thick-walled cylindrical pressure vessel

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JOURNAL OF PRESSURE VESSEL TECHNOLOGY-TRANSACTIONS OF THE ASME 2003年第4期125卷 425-431页

作者： Perl, M Ostraich, B Ben Gurion Univ Negev Dept Engn Mech Pearlstone Ctr Aeronaut Engn Studies IL-84105 Beer Sheva Israel

The effect of crack depth unevenness on the mode I stress intensity factor (SIF) distributions along the fronts of semi-elliptical surface cracks is studied. These three-dimensional radial cracks pertain to large uniform arrays of unequal-depth cracks emanating from the bore of a pressurized thick-walled cylinder The analysis is based on the "two crack depth level model," previously proposed, and is performed via the finite element (FE) method employing singular elements along the crack front. The distribution Qf K-IP-the stress intensity factor due to pressurization, for numerous uneven array configurations bearing n = n(1) +n(2) = 8 to 128 cracks, a wide range of crack depth to wall thickness ratios, a(1)/t =0.01 to 0.4, and various crack ellipticities, a(1)/c(1) = 0.3 to 1.5, are evaluated for a cylinder of radii ratio R-o/R-i = 2. To increase the accuracy of the evaluated SIFs an existing improved version of the displacement extrapolation method is used. The results clearly indicate that unevenness, as reflected in K-1P distributions, depends on both the number of cracks in the array as well as on the cracks' depths and ellipticities. The "interaction range" for the various configurations of uneven crack arrays is evaluated. The range of influence between adjacent cracks on the maximal SIF, K-Pmax is found to be dependent on the density of the array, as reflected in the inter-crack aspect-ratio, as well as on the cracks' elipticity.

关键词： uniform array cylindrical pressure vessels SURFACE CRACKS extrapolation method Pressurization pressure vessels Stress intensity factors arrays

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