Effects of strong electromagnetic coupling on the structure of satellite star tracker

The star tracker installed as an attitude measuring device on the surface of the GEO satellite is susceptible to the space charging environment and is likely to become abnormal in the orbit under the interference of strong electromagnetic pulses. In this paper, the coupling effect of the star tracker structure under a strong electromagnetic field is studied by numerical simulations and measurement tests. The electromagnetic shielding and the coupling field distributions in the star tracker under a strong electromagnetic field are simulated, with a corresponding experiment to validate the shielding effectiveness. It is indicated that the high frequency part of the strong electromagnetic field will induce a strong electromagnetic field when it is coupled with the star tracker through its optical window. At the resonance frequency point, the field strength will be enhanced, to significantly reduce the shielding effectiveness of the structure and to interfere with the internal electronic devices. Thus the protective countermeasures need to be taken. The results of this paper can provide some guidance for protecting the star tracker under a strong electromagnetic environment and some help for the on-orbit anomaly analysis.

This article demonstrates through numerical simulation in time and frequency domains, as well as corresponding shielding effectiveness testing experiments, that a strong coupling field is formed inside the star sensor under the strong field formed by a strong electromagnetic pulse source, and there is a significant risk of interference in the electronic circuit inside the star sensor circuit box. Based on a comprehensive comparison of simulation and experimental results, the following conclusions can be drawn:
1) The light shield of the star sensor cannot effectively suppress strong electromagnetic pulses and can only serve as a high pass filter. High frequency electromagnetic energy will be coupled into the cavity of the electronic component of the star sensor through the optical window of the star sensor.
2) The coupling of electromagnetic pulses at specific resonant points into the cavity will produce a significant field strength enhancement effect, making the internal field strength of the cavity much higher than the external field strength. Once a high intensity electric field is coupled to sensitive electronic circuits inside the circuit box through radiation, it will affect the normal operation of the star sensor.
Based on the above conclusions, corresponding electromagnetic reinforcement measures need to be taken to improve the shielding effectiveness of the star sensor structure. The next step is for the author to conduct research on electromagnetic protection methods and their effectiveness verification for star sensors.