Far-near-field coupling calculation method for a 110 m radio telescope based on the parabolic equation and time domain near-field physical optics
Abstract
<p indent="0mm">Recently, the electromagnetic environment surrounding large radio telescopes has become increasingly complex, with several interference sources in close proximity to radio observatories. These sources considerably influence the accuracy and efficiency of radio observations. In this work, a calculation method based on the parabolic equation and time domain physical optics was proposed to solve this issue. The research object of this investigation is an omnidirectional, movable radio telescope with a 110-m diameter in the Xinjiang Province, and the focus of this paper is to model the propagation of interference signals produced from the surrounding interference sources. This study aims to comprehensively estimate and analyze the electromagnetic coupling characteristics of these interference signals, spanning from the far field to the near field and provide a reliable foundation for effectively addressing the issue of electromagnetic interference encountered by actual large radio telescopes. First, the communication base station is taken as a representative interference source, and a high-precision terrain model is constructed based on the digital map of the surroundings of the radio telescope site. The parabolic equation is utilized to analyze the far-field radio wave propagation of the interference signal, enabling the determination of path loss and propagation factors from the interference source to the radio telescope. Second, the far field electric field calculated from the radio wave propagation is incorporated into the integration expression of the time domain physical optics method, facilitating the evaluation of the near-field coupling characteristics of the interference signal at the focus of the radio telescope. Finally, the influence of far-field interference source characteristics on the far-near-field coupling characteristics of the radio telescope is discussed. </p>
