논문 상세보기
pp.39-45
We have carried out measurements of 1.2-1.6GHz radio interferences around Seoul Radio Astronomy Observatory located in the campus of Seoul National University. We received interference signals using a pyramidal horn antenna and measured its power using a spectrum analyzer with 1MHz resolution after ~60dB amplification. In order to check the spatial characteristics, we made observations at every 30∘ 30∘ in azimuth at elevation of 30∘and60∘ 30∘and60∘ . Also, in order to check the temporal characteristics, we repeated the all-sky observations five times at every six hours. The results may be summarized as follows: (1) There are strong (≥−20dBm) (≥−20dBm) interferences between 1.2 and 1.4GHz. Particularly strong interferences are observed at 1.271 and 1.281GHz, which have maximum powers of -0.34dBm and -0.56dBm, respectively. (2) The characteristics of the interferences do not depend strongly on directions, although the interferences are in general weak at high elevation and in east-west direction. (3) The interferences appear for a very short (≤0.01s) (≤0.01s) period of time, so that the average power is much smaller than the maximum power. Strong interferences with large (≤−49.0dBm) (≤−49.0dBm) average power have been observed at 1.271, 1.281, 1.339, and 1.576GHz. At these frequencies, the interferences appear repeatedly with a period of ≤0.1s ≤0.1s By analyzing the observed power, we find that, for the strongest 1.271GHz interference, the average intensity is −171dBW/m2/Hz −171dBW/m2/Hz and that the maximum intensity is −122dBW/m2/Hz −122dBW/m2/Hz . If this interference is delivered to the detector without any shielding, then its power would be much greater than the rms noise of a typical line spectrum. Therefore, it is important to shield all the parts of receiver carefully from radio interferences. Also, without appropriate shielding, the sensitivity of a receiver could be limited by the interference.
