The Amplitude Calibration of Radio Astronomy Millimeter Wave Receiver
Abstract
The purpose of radio astronomical amplitude calibration is to convert the response of the receiving equipment to flux density for radio sources. In usual methods of radio astronomical amplitude calibration, the centimeter wave calibration mainly uses noise injection mode, which is to inject a standard noise signal into the receiver after the feed and polarizer to calibrate inside. Due to the miniaturization of millimeter wave microwave devices, the mode of noise injection is not easy to be realized, and the injection mode may introduce noise. So BTL (Bell Telephone Laboratory) first proposed to use the chopper wheel technique for millimeter wave calibration, which is to alternately place or remove the room temperature blackbody on top of the feed of receiver for calibration. Then BIMA (Berkeley Illinois Maryland Association Array) also proposed to use room temperature and thermal load to calibrate; ALMA (Atacama Large Millimeter Array) calculated the accuracy of one or two load calibration methods, and it is considered that the two load calibration method has the potential to realize the calibration accuracy of 1%, and finally it designs the mechanical arm type calibration mechanism with two temperature load; after that, the GBT (Green Bank Telescope) 4 mm band cryogenic receiver designs rotary table of calibration mechanism with two temperature load; the latest development of 3 mm band cryogenic receiver from OSO (Onsala Space Observatory) designs the beam switching of calibration mechanism with two temperature load. The QTT (Qi Tai Telescope) project of the Xinjiang Astronomical Observatory of Chinese Academy of Sciences has promoted the development process of millimeter wave receiver. In order to improve the amplitude calibration accuracy of millimeter wave, the related pre-research has begun.
- Publication:
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Acta Astronomica Sinica
- Pub Date:
- September 2018
- Bibcode:
- 2018AcASn..59...42W
- Keywords:
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- telescopes;
- techniques: radar astronomy;
- methods: observational