Experimental implementation of a synthesized two-dimensional phased array for transcranial imaging with aberration correction

2017 ◽  
Vol 141 (5) ◽  
pp. 3613-3613 ◽  
Author(s):  
Sergey Tsysar ◽  
Victor D. Svet ◽  
Petr V. Yuldashev ◽  
Vera Khokhlova ◽  
Oleg Sapozhnikov
Keyword(s):  
Phased Array ◽  
Aberration Correction ◽  
Two Dimensional ◽  
Experimental Implementation ◽  
Transcranial Imaging

Design of Two-Dimensional Ultrasonic Phased Array Transducers

2005 ◽  
Vol 127 (3) ◽  
pp. 336-344 ◽  
Author(s):  
Shyamal C. Mondal ◽  
Paul D. Wilcox ◽  
Bruce W. Drinkwater
Keyword(s):  
Phased Array ◽  
Three Dimensional ◽  
Array Element ◽  
Two Dimensional ◽  
Circular Array ◽  
Single Location ◽  
Ultrasonic Phased Array ◽  
3D Point Spread Function ◽  
3D Volume ◽  
Simulation And Evaluation

Two-dimensional (2D) phased arrays have the potential to significantly change the way in which engineering components in safety critical industries are inspected. In addition to enabling a three-dimensional (3D) volume of a component to be inspected from a single location, they could also be used in a C-scan configuration. The latter would enable any point in a component to be interrogated over a range of solid angles, allowing more accurate defect characterization and sizing. This paper describes the simulation and evaluation of grid, cross and circular 2D phased array element configurations. The aim of the cross and circle configurations is to increase the effective aperture for a given number of elements. Due to the multitude of possible array element configurations a model, based on Huygens’ principle, has been developed to allow analysis and comparison of candidate array designs. In addition to the element configuration, key issues such as element size, spacing, and frequency are discussed and quantitatively compared using the volume of the 3D point spread function (PSF) as a measurand. The results of this modeling indicate that, for a given number of elements, a circular array performs best and that the element spacing should be less than half a wavelength to avoid grating lobes. A prototype circular array has been built and initial results are presented. These show that a flat bottomed hole, half a wavelength in diameter, can be imaged. Furthermore, it is shown that the volume of the 3D reflection obtained experimentally from the end of the hole compares well with the volume of the 3D PSF predicted for the array at that point.

Two-dimensional spectrum detection based on the imperfect virtually imaged phased array

2017 ◽  
Vol 59 (10) ◽  
pp. 2654-2660 ◽  
Author(s):  
Zhongwei Tan ◽  
Hongmei Li ◽  
Zhichao Ding ◽  
Lei Zhang
Keyword(s):  
Phased Array ◽  
Two Dimensional ◽  
Dimensional Spectrum ◽  
Spectrum Detection

scholarly journals A method for measuring angular bearing errors in the “antenna - radome” system in the phased-array beam scanning region

2019 ◽  
pp. 7-24
Author(s):  
I. E. Makushkin ◽  
A. E. Dorofeev ◽  
A. N. Gribanov ◽  
S. E. Gavrilova ◽  
A. I. Sinani
Keyword(s):  
Phased Array ◽  
Array Antenna ◽  
Two Dimensional ◽  
Phased Array Antenna ◽  
Angular Region ◽  
Mathematical Expressions ◽  
Initial Stage ◽  
Steerable Antenna ◽  
Release Model ◽  
Scanning Region

The paper introduces a method for measuring angular bearing errors in an antenna-radome system in a two-dimensional angular region of scanning of electronically steerable antenna, i.e. phased array antenna, active phased array antenna. The measurements were based on an antenna measuring collimator system - “compact testing ground”. The mathematical expressions used in processing the obtained data are given. To make a matrix of angular bearing errors, measurements are carried out at different angles of the heel of the antenna - radome system when the phased array antenna beam is deflected in oblique planes. To perfect the method at the initial stage, we used a quick-release model of the radome, which has the ability to introduce angular bearing errors

Decoherence in two-dimensional quantum walks with two- and four-state coins

2021 ◽  
Author(s):  
Yu-Guang Yang ◽  
Xi-Xi Wang ◽  
Jian Li ◽  
Dan Li ◽  
Yi-Hua Zhou ◽  
...  
Keyword(s):  
Quantum Correlation ◽  
Quantum Systems ◽  
Quantum Walks ◽  
Two Dimensional ◽  
Link Type ◽  
Experimental Implementation ◽  
Spatial Dimensions

Two-dimensional quantum walks using a two-state coin have simpler experimental implementation than two-dimensional quantum walks using a four-state coin. However, decoherence occurs inevitably during the evolution of quantum walks due to the coupling between the quantum systems and their environment. Thus, it is interesting to investigate the robustness against decoherence for two- and four-state two-dimensional quantum walks. Here, we investigate the effects of the decoherence on two- and four-state two-dimensional quantum walks produced by the broken-link-type noise and compare their robustness against the broken-link-type noise. Specifically, we analyze the quantum correlation between the two spatial dimensions x and y by using measurement-induced disturbance for the two-state quantum walks, i.e. the alternate walk and the Pauli walk, and the four-state quantum walks, i.e. the Grover, Hadamard and Fourier walks, respectively. Our analysis shows that the two-state walks are more robust against the broken-link-type noise than the four-state walks.

Space-time processing for «range – azimuth – elevation» measurements in non-cooperative systems of radars with phased array antennas

2021 ◽  
Author(s):  
V.V. Chapursky ◽  
A.A. Filatov ◽  
D.E. Koroteev
Keyword(s):  
Phased Array ◽  
Elevation Angle ◽  
Two Dimensional ◽  
Time Processing ◽  
Correlation Integral ◽  
Phased Array Antennas ◽  
Array Antennas ◽  
Straight Line Parallel ◽  
Straight Line ◽  
Line Parallel

The methods of measuring the three coordinates of an aircraft in the takeoff and landing mode on the runway of airfields based on the use of non - cooperative two-and three-position systems of radars with phased array antennas are considered. For these variants, general analytical expressions are obtained for the complex generalized correlation integral of space – time processing in the function of spatial coordinates, taking into account the individual directional pattern of phased array antennas. On the basis of two – dimensional profiles of the correlation integral modules «range – elevation» and «azimuth – elevation», examples of comparing particular variants of two-position and three-position systems of radars with their location on one straight line parallel runway are given. In conditions of large signal-to-noise ratios, power-law nonlinear transformations of the correlation integral correlation integral module are applied to reduce the level of side lobes in the two – dimensional sections «range – elevation» and «azimuth – elevation». The following results are obtained using examples. Two-dimensional diagrams of the correlation integral module «range – elevation» do not depend on the azimuth of the aircraft in the range of azimuth values β=0…10 ̊ and correctly display the angle of elevation and the range of the aircraft when 2…3 radars of a non-cooperative system are located on the straight line parallel runway. The two-dimensional diagrams of the correlation integral module «azimuth – elevation angle» have an interference structure, and the number and level of their side lobes increase with increasing azimuth of the aircraft. With azimuth β≥10 ̊, this can lead to ambiguity in the measurement of the azimuth and uncertainty in the elevation angle . One of the measures to reduce the side level of the diagrams of the correlation integral module can be the use of a power-law transformation of normalized diagrams exponentiation of degree 3...4. An increase in the number of radars from two to three when they are located on one straight line parallel to the runway led to a decrease in the side lobes level of the «range – elevation angle» and «azimuth – elevation angle» diagrams. In this case, it may be advisable to solve the problem of optimal choice of the position of the intermediate radar on the same straight line. Calculations were also carried out for an additional example of the location of the intermediate radar of a 3-position system with its removal from the base line. At the same time, there was an increase of the side lobes level in the «azimuth – elevation angle» sections, which in the future may require additional research in terms of optimizing the placement of the radars in horizontal plane for such a radar systems.

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