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)
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& 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)