Surface accuracy of a large-scale compact antenna test range considering mechanism, metrology and alignment

Abstract

A large compact range (CR) having a width of 23 m and height of 16 m that will generate a Φ15 m quiet zone is presented. The antenna consists of 30 blocks and 76 serrated reflectors. Its mechanical accuracy is reflected in two aspects: surface precision and gap precision. In addition, the root-mean-square (RMS) surface accuracy should be less than or equal to 0.075 mm for achieving the highest operating frequency of 40 GHz, and the gaps between two segments should be controlled strictly to the tolerance of 0.4 ± 0.2 mm for avoiding gap diffraction and compensating for inter-block interference due to thermal deformation. The surface accuracy in terms of mechanical structure, metrology and alignment approach is very tight. First, a high-accuracy honeycomb sandwich panel, anisotropic back structure and spatial parallel adjustment mechanism are introduced, and the error contributions of these three mechanisms are 0.03 mm, 0.01 mm and 0.005 mm, respectively. Second, a measurement network based on laser tracker metrology was established, and the RMS error of the measurement system is controlled to 0.025 mm through the optimization of the measuring stations and weighted coordinate regression. Third, an original alignment approach that divides the entire assembly into three key phases by marked point edge-constrained surface is proposed. By performing a few iterations of onsite adjustment, the reflectors were aligned in the prescribed positions, and the gap quality was controlled effectively. Finally, the on-site alignment of the large CR is introduced. The final antenna surface RMS accuracy was up to 0.054 mm, and the gaps achieved the desired design index.

Analytical Regularization Method for axially symmetrical antennae and compact range applications

“…The reflector smoothness, in terms of the continuity of the higher derivative, is seen to have the primary contribution to the suppression of the peculiarities in the current distribution (see also [3]). In turn, better smoothness (at least continuity of the reflector curvatures) reduces the swings in behavior of the field reflected in the reactive near-field zone.…”

“…Utilization of this device gives the possibility for experimental measurement of an obstacle's scattered field and its characteristics as if the obstacle were under ideal experimental conditions -in far field zone, where radiated field is close to a plane wave. Construction of compact ranges is the subject of many publications (see [1][2][3] and references therein). Nevertheless, all such publications are based on geometrical optics techniques, the geometrical theory of diffraction, Kirchhoff's approximation and alike.…”

Iterative alignment of reflector panels for large-scale compact test range in non-metrology environment based on laser tracker

“…The laser tracker is a kind of measurement devices, featuring in high-speed, dynamic and high-accuracy characteristics, and is widely used in geometric measurements, such as antenna alignment, automotive fabrication and aircraft assembly [14]. The alignment of large-scale reflector panels referred to in [4,5,7] are all carried out using a commercial laser tracker in an undisturbed environment. However, these investigations do not offer any strategy to align the reflector panels in non-metrology environment.…”

“…High-accuracy reflector panels are important devices applied in a compact-test-range (CTR) system, the surface accuracy and dimension directly determine the quality of plane waves and the size of the quiet zone [1,2]. Owing to limitations in equipment capacity, transportation capacity, and accuracy requirements, a large-scale reflector for the CTR is usually divided into several sub-panels with suitable size to be fabricated, and then these sub-panels are individually assembled and aligned to form a high-accuracy reflecting surface using advanced measuring equipment and appropriate measurement methods [3][4][5]. Measurement errors caused by the alignment process are unavoidable, especially in non-ideal measurement environments.…”

Numerical Simulation and Experimental Research on Material Parameters Solution and Shape Control of Sandwich Panels with Aluminum Honeycomb

“…The sandwich panels with aluminum honeycomb, for their advantages of light weight, high rigidity, great intensity and good electrical property, have been widely used in fabrication of the reflectors for microwave communication equipment, such as compact antenna test range (CATR), radio telescope, millimeter-wave radar, etc. The sandwich panels obtained by vacuum flexible forming proposed by professor ZHOU (Beihang University) have been successfully applied in fabrication of the reflectors for many CATRs [1][2][3]. Although these sandwich panels obtained from this forming process provides high-precision surface, it cannot satisfy high-precision requirements of the reflector panels when the working frequency is 110GHz or higher.…”