Three necessary conditions for the validity of the Fresnel phase approximation for the near-field beam pattern of an aperture

1993 ◽  
Vol 18 (1) ◽  
pp. 73-75 ◽  
Author(s):  
L.J. Ziomek
Keyword(s):  
Necessary Conditions ◽  
Near Field ◽  
Beam Pattern ◽  
Phase Approximation

scholarly journals Method to Determine the Far-Field Beam Pattern of A Long Array From Subarray Beam Pattern Measurements

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1236
Author(s):  
Donghwan Jung ◽  
Jeasoo Kim
Keyword(s):  
Conventional Method ◽  
Field Condition ◽  
Near Field ◽  
Plane Waves ◽  
Measurement Data ◽  
Beam Pattern ◽  
Far Field ◽  
Water Tank ◽  
Discrete Line ◽  
Line Array

Beam pattern measurement is essential to verifying the performance of an array sonar. However, common problems in beam pattern measurement of arrays include constraints on achieving the far-field condition and reaching plane waves mainly due to limited measurement space as in acoustic water tank. For this purpose, the conventional method of measuring beam patterns in limited spaces, which transform near-field measurement data into far-field results, is used. However, the conventional method is time-consuming because of the dense spatial sampling. Hence, we devised a method to measure the beam pattern of a discrete line array in limited space based on the subarray method. In this method, a discrete line array with a measurement space that does not satisfy the far-field condition is divided into several subarrays, and the beam pattern of the line array can then be determined from the subarray measurements by the spatial convolution that is equivalent to the multiplication of beam pattern. The proposed method was verified through simulation and experimental measurement on a line array with 256 elements of 16 subarrays.

Beam pattern formation and on‐/off‐axis pressure in the near field through elastic structures

2000 ◽  
Vol 108 (5) ◽  
pp. 2637-2637
Author(s):  
Fernando García‐Osuna ◽  
Elmer L. Hixson ◽  
Augusto L. Podio
Keyword(s):  
Pattern Formation ◽  
Near Field ◽  
Beam Pattern ◽  
Elastic Structures

scholarly journals Study on the Beam Pattern Correction in Transmitting Near-Field Measurements of a Digital Multi-Function Radar

2020 ◽  
Vol 31 (2) ◽  
pp. 173-187
Author(s):  
JoungMyoung Joo ◽  
Heeduck Chae ◽  
Jongkuk Park ◽  
Hyung-Suk Jin ◽  
Yeon-Duk Kang ◽  
...  
Keyword(s):  
Near Field ◽  
Field Measurements ◽  
Beam Pattern

Near-Field Uniform Beams for Pulsed Doppler Ultrasound

1980 ◽  
Vol 2 (4) ◽  
pp. 324-337 ◽  
Author(s):  
Chong-Cheng Fu ◽  
Sharbel E. Noujaim ◽  
Robert S. Jaffe ◽  
Levy Gerzberg ◽  
Roger D. Melen
Keyword(s):  
Flow Measurement ◽  
Pattern Analysis ◽  
Ultrasonic Transducer ◽  
Near Field ◽  
Ultrasonic Field ◽  
Beam Pattern ◽  
Field Approach ◽  
Pulsed Doppler Ultrasound ◽  
Pulsed Ultrasonic

A mathematical model for the beam pattern of a pulsed ultrasonic transducer is introduced. Beam-pattern analysis and simulation of a circular transducer based on this model agree well with the experimental results. It is demonstrated that, in its near field, the pulsed transducer is capable of generating a good approximation to a uniform ultrasonic field which cannot be achieved with a cw transducer. Preliminary error analysis indicates that the near-field beam pattern of the pulsed transducer is suitable for quantitative blood-flow measurement, and design criteria are developed for this application. A prototype has been fabricated and tested in in-vitro experiments, and the results verify the feasibility of the quantitative blood flowmeter principle and the pulsed-transducer near-field approach to the formation of uniform beams.

scholarly journals Analysis of dual-band matching of an ends-fed dipole-like antenna and a coaxial line

2020 ◽  
pp. 27-31
Author(s):  
S. A. Alekseytsev ◽  
A. P. Gorbachev
Keyword(s):  
Necessary Conditions ◽  
Near Field ◽  
Coaxial Line ◽  
Dual Band ◽  
Frequency Range ◽  
Single Body ◽  
The Difference ◽  
The Impact ◽  
Analytical Approaches ◽  
Antenna Input

The problem of dual/multi-band radiation of a single-body antenna is of a great topicality today when there is a continuing development of wireless communications both for civil and military purposes. The estimation of dual-band performance of endsfed dipole-like radiator, in particular, its matching with a standard purely active resistance coaxial line is given in the paper. The focus was on stating the necessary conditions and requirements on the geometric sizes of the structure under investigation and the frequency range it have to be analyzed through. It is also considered how to decrease amount of calculations needed at the starting stage of the antenna designing that includes the exact analytical approaches for near field calculations. This decrease is based on the difference in the impact the parameters under consideration have on the antenna input impedance. For the crucial electrodynamics characteristics calculations the induced electromotive forces (EMF) method is used, which has established itself as one of the most convenient in this field.

Reconfigurable Near-Field Beam Pattern Measurement System From 0.03 to 1.6 THz

2016 ◽  
Vol 6 (2) ◽  
pp. 300-305 ◽  
Author(s):  
Alvaro Gonzalez ◽  
Yasunori Fujii ◽  
Takafumi Kojima ◽  
Shin'ichiro Asayama
Keyword(s):  
Measurement System ◽  
Near Field ◽  
Beam Pattern

Near-field beam pattern measurement of qualification model of ALMA band 8 (385–500 GHz) cartridge receiver

2009 ◽  
Vol 24 (1-3) ◽  
pp. 89-107 ◽  
Author(s):  
Masato Naruse ◽  
Tetsuya Ito ◽  
Yutaro Sekimoto ◽  
Hiroyuki Toba ◽  
Naohisa Satou ◽  
...  
Keyword(s):  
Near Field ◽  
Beam Pattern

Methodology for a sub-millimeter near-field beam pattern measurement system

2014 ◽  
Author(s):  
Kristina K. Davis ◽  
Chris Groppi ◽  
Hamdi Mani ◽  
Caleb Wheeler ◽  
Chris Walker
Keyword(s):  
Measurement System ◽  
Near Field ◽  
Beam Pattern
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