International Journal of Antennas and Propagation / 2018 / Article / Tab 9

Review Article

Active Surface Compensation for Large Radio Telescope Antennas

Table 9

Critical performance parameters and design options for QTT.

Major technical parametersAperture110 m
Work frequency150 MHz–115 GHz
Antenna typeShaped Gregorian
Surface precision of main reflector<0.2 mm (when active surface is available)
<0.6 mm (when active surface is not available)
Surface precision of subreflector<0.07 mm
Beam pointing precision<2.5 arcs (when wind speed is 4 m/s)
Structural weightPitching structure < 3000 t
Azimuth frame < 2500 t
Range of pitch angle7°–89°
Range of azimuth angle±270°

Design scheme of actuatorsWeight<10 kg
Stroke50 mm
Positioning accuracy0.015 mm
Operating temperature range−30°C/60°C

Surface detection schemeRadio holography methodAccuracy: 0.06 mm
Theodolite methodAccuracy: 1 mm
Photogrammetric methodAccuracy: 0.04 mm
Three methods could be adopted simultaneously during observation

Surface adjustment amount calculation schemeElectromechanical coupling calculation scheme oriented to beam pointingAccording to beam pointing, employ structure deformation information, determine target surface through panel movement and fitting, and show optimal adjustment amount of actuators
Adjustment amount database should be set up for quick retrieving.

Active surface control schemeClosed-loop control with functions of real-time communication, displacement control, real-time feedback, and limit alarm
ARM microprocessor and S curve acceleration control algorithm
Multithreading control mode software

LocationQitai city, Xinjiang province, China at an altitude of 1730–2250 meters

Time pathThe project proposal of QTT was submitted in 2017, and then QTT obtained the approval in Jan 2018. The feasibility study and preliminary design had been carried out for many years, and the construction is expected to build from 2018 to 2023.