Experimental study on the effect of wind on pointing accuracy of antenna structures

Wind loads have instantaneity and turbulence characteristics that will lead to pointing errors in antenna structures, and these errors cannot be ignored in high-frequency observations. Using the Tianma 65 m radio telescope (TMRT) as an example object, the pointing errors caused by wind loads are investigated using an accelerometer system. First, the resonant frequency range of the antenna structure is used for reference to acquire useful signals through the bandpass filtering method. Then, the direct current (DC) component of these signals is filtered out using the fast discrete Fourier transform method, and the baseline of the acceleration is corrected using the least-squares method. Finally, the acceleration integral is solved approximately using the discrete trapezoidal area method, and the structural vibration displacement of the antenna is determined using a double integral of acceleration. The pointing errors are then obtained based on the displacement relationship between the primary and subreflector surfaces. When the wind speed is 3.2 m/s, the antenna pitch angle is 61.7° and the wind direction angle is 80°, the generated pitch pointing error is 3.05'', and the azimuth pointing error is 1.14''. These results are consistent with those obtained via inclinometer measurements, thus validating the signal processing method and the pointing error calculation method proposed in this paper. The research methods and data analysis results reported here provide a basis for further wind-induced pointing error correction studies.