Analysis of influence of the solar window’s thermal characteristics on thermal stability of optical communication antennas

Space laser communication optical antennas have very high requirements for the stability and uniformity of the temperature field. The GEO satellite-borne laser communication is affected by the violent alternating solar heat flow, which causes the thermal disturbance of the in-orbit temperature field of the extra-satellite optical antenna to become unstable. Reduce optical communication time. For this reason, the paper proposes a ?sun window? as a solar spectral filter device to shield solar radiation, combined with the thermal design of the optical antenna system, based on thermal simulation analysis to study the effectiveness of the solar window to suppress the thermal disturbance of the optical antenna temperature field. The research results show that the thermal control optimization design of the optical antenna system based on the "sun window" has a significant effect in suppressing the thermal disturbance of the optical antenna temperature field: the stability of the temperature field of the primary mirror is increased by 2.2 times, the stability of the temperature field of the secondary mirror is increased by 10.6 times. The uniformity of the temperature field of the secondary mirror is increased by about ten times, and the time that meets the requirements of the stability and uniformity of the optical communication antenna temperature field can be up to 24 hours per day, which is more than three times that of the solution without the "sun window".

Estimation of errors at the calibration of spectral data at the Irbene RT-32 radio telescope

We analyze calibration errors that occur during the single-dish observations at the Irbene RT-32 radio telescope when calibration is done using noise diode. Only frequency switched mode of spectral line observations is considered. The purpose of the article is to find possible values of noise diode temperature Tcal and period of switching oscillator frequency 2tq. For this, we have analyzed the formula for calculating the antenna temperature of the source. It is shown that noise diode temperature affects the standard deviation of source antenna temperature σTs and the error of source antenna temperature δTs caused by instability of system temperature. tq affects the stability of the characteristics of the receiving system. In this article, the dependencies between Tcal, tq, σTs and δTs were found and analyzed. Based on these dependencies, possible values of Tcal and tq are found.