Effect of Facet Displacement on Radiation Field and Its Application for Panel Adjustment of Large Reflector Antenna

Chinese Journal of Mechanical Engineering, Apr 2017

Large reflector antennas are widely used in radars, satellite communication, radio astronomy, and so on. The rapid developments in these fields have created demands for development of better performance and higher surface accuracy. However, low accuracy and low efficiency are the common disadvantages for traditional panel alignment and adjustment. In order to improve the surface accuracy of large reflector antenna, a new method is presented to determinate panel adjustment values from far field pattern. Based on the method of Physical Optics (PO), the effect of panel facet displacement on radiation field value is derived. Then the linear system is constructed between panel adjustment vector and far field pattern. Using the method of Singular Value Decomposition (SVD), the adjustment value for all panel adjustors are obtained by solving the linear equations. An experiment is conducted on a 3.7 m reflector antenna with 12 segmented panels. The results of simulation and test are similar, which shows that the presented method is feasible. Moreover, the discussion about validation shows that the method can be used for many cases of reflector shape. The proposed research provides the instruction to adjust surface panels efficiently and accurately.

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Effect of Facet Displacement on Radiation Field and Its Application for Panel Adjustment of Large Reflector Antenna

Effect of Facet Displacement on Radiation Field and Its Application for Panel Adjustment of Large Reflector Antenna Wei WANG 0 1 2 3 Peiyuan LIAN 0 1 2 3 Shuxin ZHANG 0 1 2 3 Binbin XIANG 0 1 2 3 Qian XU 0 1 2 3 0 Collaborative Innovation Center of Information Sensing and Understanding, Xidian University , Xi'an 710071 , China 1 Key Laboratory of Electronic Equipment Structure Design of Ministry of Education, Xidian University , Xi'an 710071 , China 2 Supported by National Natural Science Foundation of China (Grant Nos. 51490661, 51490660, 51205301) , National Key Basic Research Program of China (973 Program , Grant No. 2015CB857100) , and Special Funding for Key Laboratory of Xinjiang Uygur Autonomous Region , China (Grant No. 2014KL012) 3 Xinjiang Astronomical Observation, Chinese Academy of Sciences , Urumqi 830011 , China Large reflector antennas are widely used in radars, satellite communication, radio astronomy, and so on. The rapid developments in these fields have created demands for development of better performance and higher surface accuracy. However, low accuracy and low efficiency are the common disadvantages for traditional panel alignment and adjustment. In order to improve the surface accuracy of large reflector antenna, a new method is presented to determinate panel adjustment values from far field pattern. Based on the method of Physical Optics (PO), the effect of panel facet displacement on radiation field value is derived. Then the linear system is constructed between panel adjustment vector and far field pattern. Using the method of Singular Value Decomposition (SVD), the adjustment value for all panel adjustors are obtained by solving the linear equations. An experiment is conducted on a 3.7 m reflector antenna with 12 segmented panels. The results of simulation and test are similar, which shows that the presented method is feasible. Moreover, the discussion about validation shows that the method can be used for many cases of reflector shape. The proposed research provides the instruction to adjust surface panels efficiently and accurately. Reflector antennas; Surface accuracy; Radiation field; Reflector antenna mechanical factors; Electromechanical effects; Panel adjustment; Singular value decomposition (SVD) - & Shuxin ZHANG 1 Introduction With the development of such fields as deep space communication, remote sensing and radio astronomy etc., many large reflector antennas take a great role because they can provide the enhanced data transmission, very high gain and lower noise radiations [1, 2]. However, there are many mechanical factors which affect strongly the electrical performance of reflector antennas [3–6]. In order to meet the requirements of science and technology, reflector antennas are correspondently designed larger and larger in size. It is very difficult for traditional techniques to fabricate an overall shape of parabolic reflectors. Nevertheless, large reflectors (see Fig. 1) can be composed of a set of segmented panels, which are supported by three or more adjustors on the backup structure(BUS). During the period of reflector assembly, panels need to be accurately located in the desired position with proper precision. Moreover, the surface panels will be adjusted repeatedly for a long time in order to obtain better electrical performance. There are many methods to improve surface accuracy. A traditional method for panel adjustment is to measure the targets on the panel using theodolite and tape technique [7]. This kind of method takes much time with lower precision. Fig. 1 S/X dual band reflector antenna with 40 m diameter, TT&C station located in Kunming for lunar exploration program Nowadays, many industrial measuring systems such as laser ranger are broadly used in panel adjustment [8, 9]. ‘‘Radio holography’’ is an advanced method to measure and adjust surface panels. This method makes use of a well-known relationship in antenna theory: the far-field radiation pattern of reflector antenna is the Fourier transformation of the field distribution in the aperture plane of antenna. Note that this relationship applies to the amplitude/phase distributions, not to the power pattern. Thus, if we can measure the radiation pattern, in amplitude and phase distribution in the antenna aperture plane with an acceptable spatial resolution. BENNETT, et al [10] presented a sufficiently detailed analysis of this method to draw the attention of radio astronomers. SCOTT and RYLE [11] used the new Cambridge 5 km array to measure the shape of four of the eight antennas, using a celestial radio point source and the remaining antennas to provide the reference signal Simulation algorithms were developed by RAHMAT-SAMII [12] and others [13–16], adding to the practicability of the method. Using the giant water vapour maser at 22 GHz in Orion as a source, MORRIS, et al [17] achieved a measurement accuracy of 30 microns and were set the surface of the IRAM 30 m millimeter telescope t (...truncated)


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Wei WANG, Peiyuan LIAN, Shuxin ZHANG, Binbin XIANG, Qian XU. Effect of Facet Displacement on Radiation Field and Its Application for Panel Adjustment of Large Reflector Antenna, Chinese Journal of Mechanical Engineering, 2017, pp. 578-586, Volume 30, Issue 3, DOI: 10.1007/s10033-017-0135-z