EMC design for actuators in the FAST reflector

An active reflector is one of the three main innovations incorporated in the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The deformation of such a huge spherically shaped reflector into different transient parabolic shapes is achieved by using 2225 hydraulic actuators which change...

Full description

Saved in:
Bibliographic Details
Published inResearch in astronomy and astrophysics Vol. 18; no. 4; pp. 48 - 53
Main Authors Zhang, Hai-Yan, Wu, Ming-Chang, Yue, You-Ling, Gan, Heng-Qian, Hu, Hao, Huang, Shi-Jie
Format Journal Article
LanguageEnglish
Published Beijing National Astronomical Observatories, CAS and IOP Publishing Ltd 01.04.2018
IOP Publishing
Subjects
active reflector: actuator
Actuator design
Apertures
Astronomy
Cables
Electromagnetic compatibility
Electromagnetic shielding
Fluid filters
Frequency ranges
Optical fibers
Power lines
Radio astronomy
radio telescope
Radio telescopes
Receivers & amplifiers
Telescopes
Online AccessGet full text

Cover

More Information
Summary:An active reflector is one of the three main innovations incorporated in the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The deformation of such a huge spherically shaped reflector into different transient parabolic shapes is achieved by using 2225 hydraulic actuators which change the position of the 2225 nodes through the connected down tied cables. For each different tracking process of the telescope, more than 1/3 of these 2225 actuators must be in operation to tune the parabolic aperture accurately and meet the surface error restriction. This means that some of these actuators are inevitably located within the main beam of the receiver, and Electromagnetic Interference (EMI) from the actuators must be mitigated to ensure the scientific output of the telescope. Based on the threshold level of interference detrimental to radio astronomy described in ITU-R Recommendation RA.769 and EMI measurements, the shielding efficiency (SE) requirement for each actuator is set to be 80 dB in the frequency range from 70 MHz to 3 GHz. Therefore, Electromagnetic Compatibility (EMC) was taken into account in the actuator design by measures such as power line filters, optical fibers, shielding enclosures and other structural measures. In 2015, all the actuators had been installed at the FAST site. Till now, no apparent EMI from the actuators has been detected by the receiver, which demonstrates the effectiveness of these EMC measures.
ISSN:1674-4527
DOI:10.1088/1674-4527/18/4/48