Calculation method of separation angles and interference between satellite and radio-relay links in atmospheric refraction condition

• Published in: Electronics & communications in Japan. Part 1, Communications Communications, 1991-06, Vol.74 (6), p.51-59
• Main Authors: Ooi, Tetsuo, Saito, Yoichi
• Format: Article
• Language: English
• ISSN: 8756-6621; 1520-6424
• DOI: 10.1002/ecja.4410740606

When the frequency sharing between the fixed satellite communication system and the radio relay system is realized, it is indispensable to evaluate the interference noise in the design of each channel. Especially, to treat the interference between the satellite station and the terrestrial radio‐relay station, it is necessary to find the separation angle between the radio‐relay antenna beam and the geostationary satellite orbit. This paper presents a method for evaluation of the separation angle with the atmospheric beam refraction. The beam refraction angle is given as an integration along the beam path of the infinitesimal rate of change of the elevation angle for the altitude. A simple approximate expression is derived for facilitating the derivation of the separation angle. By comparison with the rigorous theory, the approximation errors are shown to be small enough for all practical purposes. A computation method for the separation angle is described for a terrestrial radio‐relay station position and an antenna beam direction from the geostationary satellite orbit. As an application, an actual radio‐relay link is chosen for which the separation angle distribution and the interference noise distribution are derived. By means of the computational method presented in this paper, the interference noise from the satellite station to the terrestrial radio‐relay station is now evaluated rather easily.