• A Compensation Method for Active Phased Array Antennas : Using a Strain-Electromagnetic Coupling Model

      Shi, Yu; Wang, Congsi; Wang, Yan; Yuan, Shuai; Duan, Baoyan; Lian, Peiyuan; Xue, Song; Du, Biao; Gao, Wei; Wang, Zhihai; et al.
      Physical deformation due to service loads seriously degrades the electromagnetic performance of active phased array antennas. However, traditional displacement-based compensation methods are moderately difficult to use because displacement measurements generally require stable references, which are hard to realize for antennas in service. For deformed antennas, strain information is directly related to their displacement, and strain sensors can overcome carrier platform constraints to measure real-time strain without affecting the antenna radiation-field distribution. We thus present a compensation method based on strain information for in-service antennas. First, the minimum number of strain sensors is determined as the main modal-order-based modal effective mass fraction. According to the modal method and analysis of spatial phase-distribution errors related to strain, a coupled strain-electromagnetic model is established to evaluate antenna performance from the measured strain. The corresponding excitation phase from the measured strain is adjusted to compensate antenna performance. Finally, the method is experimentally validated using an X-band active phased array antenna under the influence of typical deformation conditions for both boresightand scanned beams. The results demonstrate that the presented method can effectively compensate for the performance of service antennas directly from the measured strain information.
    • Effect of Temperature on Electromagnetic Performance of Active Phased Array Antenna

      Wang, Yan; Wang, Congsi; Lian, Peiyuan; Xue, Sone; Liu, Jing; Gao, Wei; Shi, Yu; Wang, Zhihai; Yu, Kunpeng; Peng, Xuelin; et al.
      Active phased array antennas (APAAs) can suffer from the effects of harsh thermal environments, which are caused by the large quantity of power generated by densely packed T/R modules and external thermal impacts. The situation may be worse in the case of limited room and severe thermal loads, due to heat radiation and a low temperature sink. The temperature field of the antenna can be changed. Since large numbers of temperature-sensitive electronic components exist in T/R modules, excitation current output can be significantly affected and the electromagnetic performance of APAAs can be seriously degraded. However, due to a lack of quantitative analysis, it is difficult to directly estimate the effect of temperature on the electromagnetic performance of APAAs. Therefore, this study investigated the electromagnetic performance of APAAs as affected by two key factors—the uniformly distributed temperature field and the temperature gradient field—based on different antenna shapes and sizes, to provide theoretical guidance for their thermal design.
    • Space Phased Array Antenna Developments: A Perspective on Structural Design

      Wang, Congsi; Wang, Yan; Lian, Peiyuan; Xu, Qian; Shi, Yu; Jia, Yu; Du, Biao; Liu, Jing; Tang, Baofu; Xue, Song; et al.
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    • Surface adjustment strategy for a large radio telescope with adjustable dual reflectors

      Lian, Peiyuan; Wang, Congsi; Xue, Song; Xu, Qian; Shi, Yu; Jia, Yu; Xiang, Binbin; Wang, Yan; Yan, Yuefei; Xidian University; University of Chester; Chinese Academy of Sciences (IET, 2019-08-15)
      With the development of large-aperture and high-frequency radio telescopes, a surface adjustment procedure for the compensation of surface deformations has become of great importance. In this study, an innovative surface adjustment strategy is proposed to achieve an automated adjustment for the large radio telescope with adjustable dual reflectors. In the proposed strategy, a high-precision and long-distance measurement instrument is adopted and installed on the back of the sub-reflector to measure the distances and elevation angles of the target points on the main reflector. Here, two surface adjustment purposes are discussed. The first purpose is to ensure that the main reflector and sub-reflector are always positioned at their ideal locations during operation. The second purpose is to adjust the main reflector to the location of the best fitting reflector, and the sub-reflector to the focus of the best fitting reflector. Next, the calculation procedures for the adjustments of the main reflector and the sub-reflector are discussed in detail, and corresponding simulations are carried out to verify the proposed method. The results show that the proposed strategy is effective. This study can provide helpful guidance for the design of automated surface adjustments for large telescopes.