Effects of Nonuniform Surface Errors Along the Radius on Reflector’s Radiation Characteristic and Its Quality Evaluation

Int J RF Microw Comput Aided Eng

et al. 2019

Self Cite

A large reflector antenna generally consists of several rings of panels and panel installation errors (PIEs) are inevitable during the panel installation process. In this paper, a mathematical model is developed to analyze the effects of PIEs on reflector's average power pattern. Whether for the PIEs of each ring of panels or for the PIEs of all the panels for the whole reflector, the proposed model can be used to calculate the average power pattern with the root-meansquare value of the PIEs, and its correctness is demonstrated by the results calculated by Monte Carlo simulation. For a given paneled reflector, the peak gain losses and the first side lobe level increments caused by different PIEs for the whole reflector are presented. Then, through an analysis for each ring of panels, including the effects of different amplitude aperture distribution functions and different ratios of focal length to diameter (F/D ratios), the results clearly show that the PIEs of the panels for different rings have different effects on the reflector's average power pattern, and valuable results are obtained. The derived results will greatly benefit the panel installation and adjustment of large reflector antennas. K E Y W O R D S average power pattern, panel installation error (PIE), reflector antenna

Section: Formulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of reflector antenna panel installation errors on average power pattern

Int J RF Microw Comput Aided Eng

et al. 2019

Self Cite

“…More specifically, a large aperture can result in large gravitational deformation, and the telescope can also become more sensitive to inevitable external environmental impacts, such as temperature and wind [2][3][4]. Numerous research papers have analysed the effect of the surface deformation of a radio telescope on its electromagnetic performance [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Surface adjustment strategy for a large radio telescope with adjustable dual reflectors

IET Microwaves, Antennas & Propagation

Xue

et al. 2019

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With the development of large-aperture and high-frequency radio telescopes, a surface adjustment procedure for the compensation of surface deformations has become of great importance. In this paper, an innovative surface adjustment strategy is proposed to achieve an automated adjustment for the large radio telescope with adjustable dual reflectors. In the proposed strategy, a high-precision and long-distance measurement instrument is adopted and installed on the back of the sub-reflector to measure the distances and elevation angles of the target points on the main reflector. Here, two surface adjustment purposes are discussed. The first purpose is to ensure that the main reflector and the sub-reflector are always positioned at their ideal locations during operation. The second purpose is to adjust the main reflector to the location of the best fitting reflector, and the sub-reflector to the focus of the best fitting reflector. Next, the calculation procedures for the adjustments of the main reflector and the sub-reflector are discussed in detail, and corresponding simulations are carried out to verify the proposed method. The results show that the proposed strategy is effective. This paper can provide helpful guidance for the design of automated surface adjustments for large telescopes.

“…Duan and Wang [12] studied the influence of surface random errors and systematic errors on the EMP and established an optimization model for the integrated mechanical-electromagnetic performance. Lian et al [13] developed a multiobjective optimization model to analyze the effects of surface errors' nonuniformity along the radius on the reflector's radiation characteristic and discussed that for the same RMS of errors for the whole reflector, different distributions along the radius result in different gain losses and sidelobe levels. However, these works consider only one type of error distribution, such as the variations in radial or azimuthal directions, and hence, they cannot represent all situations that influence of the arbitrary error distributions.…”

Section: Introductionmentioning

confidence: 99%

Effect of Surface Error Distribution and Aberration on Electromagnetic Performance of a Reflector Antenna

Xiang

International Journal of Antennas and Propagation

2019

Self Cite

In this paper, a method based on the Zernike distribution and the optical aberration is proposed to investigate the effects of the distribution characteristics of surface distortions of a reflector antenna on its electromagnetic performance (EMP). For large-scale errors, an analytical model is introduced to describe the arbitrary distortions, based on the orthogonal Zernike polynomials. The effects of error distribution described by the Zernike series on typical EMP are analyzed. The numerical results indicate that the distortions in the distribution feature of defocus or spherical aberration have a greater impact on gain, and the distribution feature of tilt or coma mainly influences boresight offset; the distribution feature of defocus, astigmatism, and spherical aberration has a greater impact on sidelobe levels. The results indicate that the beam contour patterns are related to the distribution forms of distortions and are similar with the same aberration feature. On the basis of the Seidel aberration, the relationships between typical EMP and the aberration coefficient are presented. Based on these, the error profile of the primary influence and the approximate feature of EMP can be determined, and the antenna performance can be predicted in a simple manner.