Reflection Test at Planar Near Field Range for Reflector Antenna

2004 ◽  
Author(s):  
Jeom-Hun Lee ◽  
S. Yun ◽  
J. Park ◽  
S. Lee ◽  
Y. Kim ◽  
...  
Keyword(s):  
Near Field ◽  
Reflector Antenna ◽  
Field Range

scholarly journals Ka-Band Lightweight High-Efficiency Wideband 3D Printed Reflector Antenna

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Yu Zhai ◽  
Ding Xu ◽  
Yan Zhang
Keyword(s):  
High Efficiency ◽  
Near Field ◽  
Side Lobe ◽  
High Gain ◽  
Reflector Antenna ◽  
Field Analysis ◽  
Side Lobe Level ◽  
Ka Band ◽  
3D Printed ◽  
Reflecting Surface

This paper presents a lightweight, cost-efficient, wideband, and high-gain 3D printed parabolic reflector antenna in the Ka-band. A 10 λ reflector is printed with polylactic acid- (PLA-) based material that is a biodegradable type of plastic, preferred in 3D printing. The reflecting surface is made up of multiple stacked layers of copper tape, thick enough to function as a reflecting surface (which is found 4 mm). A conical horn is used for the incident field. A center-fed method has been used to converge the energy in the broadside direction. The proposed antenna results measured a gain of 27.8 dBi, a side lobe level (SLL) of −22 dB, and a maximum of 61.2% aperture efficiency (at 30 GHz). A near-field analysis in terms of amplitude and phase has also been presented which authenticates the accurate spherical to planar wavefront transformation in the scattered field.

Non-Destructive Detection of GIS Aluminum Alloy Shell Weld Based on Oblique Incidence Full Focus Method

2020 ◽  
Vol 1007 ◽  
pp. 105-110
Author(s):  
Xin Xin Wang ◽  
Cheng He ◽  
Pu Zhi Zhao ◽  
Yi Zheng ◽  
Shi Hao Jiang ◽  
...  
Keyword(s):  
Oblique Incidence ◽  
Near Field ◽  
Calibration Coefficient ◽  
Quantitative Detection ◽  
Imaging Method ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Field Range ◽  
Weld Defects ◽  
Non Destructive

In this paper, a new ultrasonic phased array full focus imaging method based on oblique incidence is proposed to solve the problem of the non-destructive testing of the internal defects in the GIS (gas insulated switchgear) shell welds. By using wedge coupling, the measured weld is far away from the near-field range of the transducer, and the detection angle range can be increased by changing the propagation direction of the acoustic beam. Based on Snell's law, the propagation characteristics of the ultrasonic wave in the interface are studied. On the basis of the conventional ultrasonic array matrix and the full focus imaging algorithm, by introducing the energy attenuation calibration coefficient of the acoustic wave propagation through the wedge, the correction amplitude of the specific focus point p(x, z) is obtained, The non-destructive testing of weld defects of GIS shell in the spot is carried out, and the test results show that the qualitative and quantitative detection of the weld defects can be well realized by using this method.

scholarly journals Lidar Overlap Function Determination Using the Raman Lidar Signals

2020 ◽  
Vol 237 ◽  
pp. 07018
Author(s):  
Jaswant ◽  
Shishir Kumar Singh ◽  
Radhakrishnan S.R. ◽  
Devesh Shukla ◽  
Chhemendra Sharma
Keyword(s):  
Optical Properties ◽  
Simple Technique ◽  
Near Field ◽  
Lower Atmosphere ◽  
Raman Lidar ◽  
Lidar System ◽  
Field Range ◽  
The Mean ◽  
Overlap Factor

The determination of vertical distribution of optical properties of clouds and aerosols using the lidar system is affected by the incomplete overlap between the field of view of transmitter i.e. laser beam & the receiver in the near‐field range. Thus, the study of vertical profiles of aerosol optical properties in the lower atmosphere is erroneous without the correction of lidar overlap function. Here we have analysed the effect of overlap using a simple technique proposed by Ansmann and Wandinger to determine overlap function. We have determined the overlap factor for 5 different days of June 2016 and then calculated the mean overlap profile and determined the relative deviation of each day with respect to mean overlap factor. Results reveal that the complete overlap was achieved beyond 300 meters.

scholarly journals Similarity of the asymmetric swirl generator and a double bend in the near-field range

2019 ◽  
Vol 70 ◽  
pp. 101647 ◽  
Author(s):  
M. Straka ◽  
T. Eichler ◽  
C. Koglin ◽  
J. Rose
Keyword(s):  
Near Field ◽  
Field Range ◽  
Swirl Generator

Segmental orifice plates and the emulation of the 90°-bend

2020 ◽  
Vol 87 (1) ◽  
pp. 18-31
Author(s):  
Martin Straka ◽  
Christian Koglin ◽  
Thomas Eichler
Keyword(s):  
Near Field ◽  
Flow Conditions ◽  
Structural Element ◽  
Field Range ◽  
Flow Meters ◽  
Piping Systems ◽  
Approval Procedure ◽  
Electromagnetic Flow Meter ◽  
Coverage Rates ◽  
Water Meters

AbstractThe 90 ° - bend represents the most common structural element in piping systems and can have a significant impact on the measuring accuracy of flow meters installed downstream. Within the type-approval procedure of water meters, its impact is emulated by means of a segmental orifice plate with a segment area of 7 % (SOP7). In research and development, coverage rates of 33 % (SOP33) or more are sometimes used as an alternative. The purpose of this study is to evaluate the comparability of the flow conditions and their influence on the measurement deviation of flow meters, which is the basic requirement for using SOPs as a substitute for the 90°- bend. We present laser Doppler measurements downstream of an SOP33 and a 90°- bend and describe the flow development in a distance range from 2 to 30 diameters. Besides a quantitative comparison with performance indicators, the measurements are used to model the response of an ultrasonic and electromagnetic flow meter, including recent investigations of an SOP7. The results demonstrate the consistently poor agreement between the SOP7 and the 90°- bend, whereas the SOP33 provides similar flow conditions starting at a distance of 10 diameters. Further studies are necessary to develop a disturbance generator emulating the near-field range.

scholarly journals Compact short-pulse laser for near-field range-gated imaging

1997 ◽  
Author(s):  
Fred J. Zutavern ◽  
Wesley D. Helgeson ◽  
Guillermo M. Loubriel ◽  
George J. Yates ◽  
Robert A. Gallegos ◽  
...  
Keyword(s):  
Pulse Laser ◽  
Short Pulse ◽  
Near Field ◽  
Field Range ◽  
Short Pulse Laser ◽  
Gated Imaging
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