scholarly journals Deformation measurement by single spherical near-field intensity measurement for large reflector antenna

2021 ◽  
Vol 21 (10) ◽  
pp. 258
Author(s):  
Qian Ye ◽  
Bo-Yang Wang ◽  
Qiang Yao ◽  
Jin-Qing Wang ◽  
Qing-Hui Liu ◽  
...  
Keyword(s):  
Surface Deformation ◽  
Focal Point ◽  
Spherical Surface ◽  
Outer Space ◽  
Near Field ◽  
Elevation Angle ◽  
Physical Optics ◽  
Electric Intensity ◽  
Deformation Intensity ◽  
Main Reflector

Abstract This paper presents a new method to obtain the deformation distribution on the main reflector of an antenna only by measuring the electric intensity on a spherical surface with the focal point as the center of the sphere, regardless of phase. Combining the differential geometry theory with geometric optics method, this paper has derived a deformation-intensity equation to relate the surface deformation to the intensity distribution of a spherical near-field directly. Based on the finite difference method (FDM) and Gauss-Seidel iteration, deformation has been calculated from intensity simulated by geometrical optics (GO) and physical optics (PO) methods, respectively, with relatively small errors, which prove the effectiveness of the equation proposed in this paper. By means of this method, it is possible to measure the deformation only by scanning the electric intensity of a single hemispherical near-field whose area is only about 1/15 of the aperture. The measurement only needs a plane wave at any frequency as the incident wave, which means that both the signals from the outer space satellite and the far-field artificial beacon could be used as the sources. The scanning can be realized no matter what attitude and elevation angle the antenna is in because the size and angle of the hemisphere are changeable.

A physical optics based near-field analysis method for the design of dual polarized fan beam shaped reflector antennas

2016 ◽  
Vol 70 (2) ◽  
pp. 132-137 ◽  
Author(s):  
E. Bagheri-Korani ◽  
K. Mohammadpour-Aghdam ◽  
M. Ahmadi-Boroujeni ◽  
E. Arbabi ◽  
M. Nemati
Keyword(s):  
Near Field ◽  
Field Analysis ◽  
Physical Optics ◽  
Analysis Method ◽  
Reflector Antennas ◽  
Dual Polarized

Modified physical optics algorithm for near field scattering

2018 ◽  
Vol 27 (11) ◽  
pp. 114102 ◽  
Author(s):  
Bin Chen ◽  
Chuangming Tong
Keyword(s):  
Near Field ◽  
Physical Optics

A physical optics approach to near field RCS computations

1996 ◽  
Vol 51 (5-6) ◽  
pp. 219-226
Author(s):  
Philippe Pouliguen ◽  
Laurent Desclos
Keyword(s):  
Near Field ◽  
Physical Optics

Conversion of a Telecommunications Antenna into a Radio Telescope: Laser Scanner Measurements of Optics and Dish Surface Quality of a Cassegrain Antenna

2019 ◽  
Vol 08 (03) ◽  
pp. 1950010
Author(s):  
Asif Rasha ◽  
Tim Natusch ◽  
Christophe Granet ◽  
Sergei Gulyaev
Keyword(s):  
Surface Quality ◽  
Radio Telescope ◽  
Surface Deformation ◽  
Elevation Angle ◽  
Laser Scanner ◽  
Length Variation ◽  
Cassegrain Antenna ◽  
Telescope Optics

A number of countries have identified redundant large telecommunications antennas (TA) and indicated their intention to convert them into radio telescopes (RT). As the efficiency of a parabolic dish radio telescope depends on its surface quality and optical alignment, a careful assessment of these properties should be undertaken before conversion. Here, as a case study, we describe a laser scanning (LS) procedure we developed and used for the Warkworth 30[Formula: see text]m Cassegrain antenna. To investigate gravity-induced mechanical deformation of the antenna surfaces and structure, we conducted measurements at elevation angles ranging from 6 to 90 degrees. The ability of a laser scanner to survey its nominal [Formula: see text] steradian surroundings allows for simultaneous study of the main and subreflectors, readily permitting a dynamic investigation of variation of the telescope optics as elevation changes occur. In particular, the method we present here allows determination of the surface quality of both main and subreflectors, the displacement between centers of the reflectors, their relative rotations and focal length variation as a function of elevation angle. We discuss details of settings, measurements, data processing and analysis focusing on possible difficulties and pitfalls. In our case study, no significant elevation-dependent surface deformation of the reflectors was observed, with the overall standard deviation of the postfit residuals varying between 1.0 and 1.7[Formula: see text]mm as elevation angle changes from 90∘ to 6∘, respectively. We, therefore, conclude that in our case both the main reflector and the subreflector, as well as the telescope optics, remain unaffected by gravitational deformation within the accuracy of the measurements, a conclusion that can possibly be extended to the similar class of TA currently considered for conversion.

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