The study on electromagnetic noise of satellite ground station

During the design of a satellite ground station, a large number of calculation formulas and complicated procedures may be involved, which causes unreasonable performance and price ratio and great waste. The authors of this paper, having comprehensively studied the link formulas and some engineering experiences on satellite receiving, and through strict mathematic deductions, have set up a new mathematic model on the antenna diameter and unweighted video S/N: D=10^x. Where x=0.05S/N-0.05EIRP-10.91598564-0.5Lgη+Lgd+0.05ΔL+0.5Lg(T_a +T_r)-LgΔf_v+1.5Lgf_v-0.05F. D: caliber size (diameter) of the satellite receiving antenna (m). S/N: video signal to noise ratio (dB). EIRP: equivalent wall directional radiation from the satellite to the area where the ground station is (dB·w). η: antenna efficiency, usually is taken as 0.65 in engineering. d: distance from satellite to ground station (m). ΔL: down-going additional loss (dB). Δfv: video frequency deviation (Hz). fv: Max. video frequency (Hz). F: deacentuation improving factor. Ta: antenna noise temperature. Tr: HF tuner noise temperature. The unweighted video S/N can directly indicate the quality of pictures (which is usually required by users). The establishment of this formula gives a direct relationship between the antenna diameter D and the S/N, and makes it possible to draw a D-S/N curve, showing that the D-S/N relationship is not a linear one. The satellite receiving antenna costs one-third of the total ground station, and the cost of the antenna is proportional to the square of the antenna diameter D. Therefore, the accuracy of antenna diameter is rather critical. The designer may accurately and quickly find out the D value by using the D-S/N curve when designing a specific satellite ground receiving station