Duan Baoyan

Development of active surface technology of large radio telescope antennas

Aperture expanding and frequency upgrading of full steerable antennas make the electrical performance of the antennas difficult to guarantee, and that radio telescopes operate in a complex environment, so it has to improve the performance by some methods like mechanical or electronic compensation. To control the pointing accuracy and the detecting distance of antennas, we must adjust the position and the surface shape of shaped reflectors, in another word, the active surface adjustment is the most effective way. Therefore, this article describes the situation and status of applications of active surface adjustment. Then, it summarizes the basic principle and the applications of active surface adjustment and particularly analyzes the key technologies which include the calculation of actuator movement, the block design of main surface, the actuator design, the active surface control system and the surface profile measuring. The comparisons among four large radio telescopes of the world are discussed, which have used active surface technology. At last, it points out some suggestions on the future research of active surface technology of large radio telescopes such as QTT.

A novel design of large full-steerable reflector antenna

Aiming at the problem of self-weight and cost of 110 m large full-steerable reflector antenna, a new design scheme is proposed. Compared with the conventional scheme, the self-weight, drive power and cost can be reduced by 1/2, 2/3 and 1 orders of magnitude. Firstly, an ultra-light prestressed cable-truss structure is proposed to replace the traditional rigid heavy rigid truss structure. Then, a novel parallel servo mechanism is proposed to replace the conventional Az - El scanning mechanism. Furthermore, an optimization model is established based on the modularized design. Finally, the new scheme is applied to the numerical examples and a practical antenna with a diameter of 26 m, and the results verify the feasible and effective of the scheme and the method. In addition, the design scheme is extensible and can be applied to the design of large structures and devices such as antennas, weapon mounts and large solar panels in other land, sea, air and space fields.

Review of electromechanical coupling of electronic equipment

High-performance and highly accurate electronic equipment are utilized in various areas on land, in the sea, in the air, and in outer space. As a prelude to exploring the electromechanical coupling problem in electronic equipment, this paper first gives a broad overview of the state-of-the-art in electronic equipment, including concept, theory, and methodology, problem areas, hot spots, research progress, and new trends in the field. Consequently, typical examples of electronic equipment are discussed, including the microwave re ector antenna, plate-slot array antenna, active phased array antenna, and high density chassis.

Method to Enhance the Stiffness of Cable-suspended Structure for Super Antenna and Its Effect on the Electronic Performance

Considering the drawback of weak twisting stiffness of the feed cable-suspended structure for the next generation large spherical radio telescope, a method is proposed to enhance the twisting stiffness of the structure through adding the stable cable system. The stable cable system consists of three tie-down cables. The upper end and the lower end of each stable cable are connected respectively with the feed cabin and a clog through a guiding pulley. While the cable-suspended structure vibrates under some external disturbance, the stable cable system acts as a dynamic absorber to enhance the stiffness of the structure effectively. Considering the effect of weight on the shapes and the tensions of the long span cables, the nonlinear equivalent equations of the feed cable-suspended structure including the stable cable system are established. A comparison of the structural displacement responses induced by the external disturbances between the original structure and the improved structure is made. Then, the effectiveness of the proposed method is demonstrated through the experiments of 5 m scaled model. Furthermore, the antenna pattern is drawn,and the quantitative analysis is made to evaluate the effect of the stable cable system on the electromagnetic performance of the antenna in view of the gain, cross polarization, and first minor level. Both the theoretical analysis and the experiments show that the feed cable-suspended structure with stable cable system can be applied to the 500 m antenna project.

Computational Modeling for Panel Adjustment of Large Reflector Antennas

In accordance with the characteristic that large parabolic reflector antenna surface is divided into panels, based on the concept of the best-fit paraboloid (BFP), a method for panel adjustment is studied from the viewpoint of branch crossing. The transformation matrix that relates adjustments to surface errors is derived. Based on the transformation matrix, a novel mathematic model and a useful program for guiding panel adjustment are developed to determine the adjustment quantity of reflector panels. After being used in practice the results have shown that the model is of precision.