scispace - formally typeset
Search or ask a question
Topic

Phased array

About: Phased array is a research topic. Over the lifetime, 19428 publications have been published within this topic receiving 229231 citations. The topic is also known as: Phased Array Radar, PAR.


Papers
More filters
Journal ArticleDOI
TL;DR: A calibration and beamforming strategy for PAFs including interference mitigation with power spectral density (PSD) estimation bias correction and validated using numerical simulations and experimental data from a 19-element PAF on the Green Bank 20-m telescope is proposed.
Abstract: Relative to traditional waveguide feeds, phased array feeds (PAFs) for radio telescopes can increase the instrument field of view and sky survey speed. Unique challenges associated with PAF observations, including extremely low signal levels, long-term system gain stability requirements, spatially correlated noise due to mutual coupling, and tight beamshape tolerances, require the development of new array signal processing techniques for this application. We propose a calibration and beamforming strategy for PAFs including interference mitigation with power spectral density (PSD) estimation bias correction. Key efficiency metrics for single-feed instruments are extended to the array case and used to verify performance of the algorithms. These techniques are validated using numerical simulations and experimental data from a 19-element PAF on the Green Bank 20-m telescope.

107 citations

Journal ArticleDOI
TL;DR: A technique for characterizing reflectors with subwavelength dimensions by post-processing the complete data set of time traces obtained from an ultrasonic array using two algorithms is described.
Abstract: Ultrasonic arrays are increasingly widely used in nondestructive evaluation (NDE) due to their greater flexibility and potentially superior performance compared to conventional monolithic probes. The characterization of small defects remains a challenge for NDE and is of great importance for determining the impact of a defect on the integrity of a structure. In this paper, a technique for characterizing reflectors with subwavelength dimensions is described. This is achieved by post-processing the complete data set of time traces obtained from an ultrasonic array using two algorithms. The first algorithm is used to obtain information about reflector orientation and the second algorithm is used to distinguish between point-like reflectors that reflect uniformly in all directions and specular reflectors that have distinct orientations. Experimental results are presented using a commercial 64-element, 5-MHZ array on two aluminum test specimens that contain a number of machined slots and side-drilled holes. The results show that the orientation of 1-mm-long slots can be determined to within a few degrees and that the signals from 1-mm-long slots can be distinguished from that from a 1-mm-diameter circular hole. Techniques for quantifying both the orientation and the specularity of measured signals are presented and the effect of processing parameters on the accuracy of results is discussed.

107 citations

Journal ArticleDOI
TL;DR: In this article, a modified Bernstein polynomial, defined with just five parameters, is introduced which provides a flexible method to specify a variety of smooth unimodal amplitude distributions that are shown to give good sidelobe levels and aperture efficiencies.
Abstract: As various enabling technologies advance, conformal phased arrays are finding more numerous applications. Because a conformal array is curved, new far field pattern behaviors emerge and many of the traditional linear and planar phased array synthesis methods are not valid. This paper starts by reviewing the equations for the far field of a curved phased array, and provides a generalized definition of aperture efficiency appropriate for conformal arrays. A modified Bernstein polynomial, defined with just five parameters, is introduced which provides a flexible method to specify a variety of smooth unimodal amplitude distributions that are shown to give good sidelobe levels and aperture efficiencies. By using particle swarm optimization of the modified Bernstein polynomial parameters constrained to provide a specified aperture efficiency, a family of aperture distributions and corresponding far field patterns is produced that allows aperture efficiency to be traded for sidelobe level.

106 citations

Journal ArticleDOI
TL;DR: In this article, the authors compare the performance of 1D and 1.5D multi-row array transducers with 1.25D and 2D arrays for adaptive acoustics and two-dimensional beam steering.
Abstract: Present 1D phased array probes have outstanding lateral and axial resolution, but their elevation performance is determined by a fixed aperture focused at a fixed range. Multi-row array transducers can provide significantly improved elevation performance in return for "modest" increases in probe and system complexity. Time domain simulations of elevation beam profiles are used to compare several types of multi-row probes. The elevation aperture of a 1.25D probe increases with range, but the elevation focusing of that aperture is static and determined principally by a mechanical lens with a fixed focus (or foci). 1.25D probes can provide substantially better near- and far-field slice thickness performance than 1D probes and require no additional system beamformer channels. 1.5D, probes use additional beamformer channels to provide dynamic focusing and apodization in elevation. 1.5D probes can provide detail resolution comparable to, and contrast resolution substantially better than, 1.25D probes, particularly in the mid- and far-field. Further increases in system channel count allow the use of 1.75D and 2D arrays for adaptive acoustics and two-dimensional beam steering. Significant improvements in clinical image quality can be expected as multi-row probes become increasingly available in the marketplace.

106 citations

Journal ArticleDOI
TL;DR: In this article, a novel approach of true-time delay (TTD) optical feeder for phased-array antennas is proposed and demonstrated by employing tunable lasers and one wide bandwidth chirped-fiber grating as dispersive element.
Abstract: A novel approach of true-time delay (TTD) optical feeder for phased-array antennas is proposed and demonstrated. A compact size continuously variable TTD is achieved by employing tunable lasers and one wide bandwidth chirped-fiber grating as dispersive element. A high-resolution performance (5.3 ps) is obtained for a 26-GHz phased-array antenna employing narrow tuning bandwidth lasers with a wavelength stability of 0.005 nm and a 4 nm bandwidth chirped grating.

106 citations


Network Information
Related Topics (5)
Antenna (radio)
208K papers, 1.8M citations
87% related
Radar
91.6K papers, 1M citations
86% related
Transmitter
61.9K papers, 874.2K citations
82% related
Amplifier
163.9K papers, 1.3M citations
81% related
Resonator
76.5K papers, 1M citations
81% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023373
20221,052
2021661
2020979
20191,266
20181,066