Proceedings of the IRE · 1959 · 45 citations · 4 references
EngineeringCommunicationElectrical EngineeringAntennasMicrowave EngineeringWireless CommunicationsCommunications SubsystemsMicrowave AntennasReflector AntennasLow-noise AmplifiersNoise TemperatureReceiver Noise TemperatureSatellite Communication LinksSignal-to-noise RatioSpace Communication SystemsTropospheric ScatteringVery Low Frequency Propagation
Artificial earth satellites and low‑noise maser amplifiers enable microwave links using spherical satellites as passive reflectors, offering a broad‑band transatlantic communication alternative to cable or tropospheric scatter. A polar‑orbiting satellite at 3,000 mi provides intermittent visibility between Newfoundland and the Hebrides, and a constellation of 24 such satellites can maintain >7.25° elevation 99 % of the time; with 100‑ft spheres, 150‑ft antennas, and 20 K noise, 85 kW at 2 GHz or 9.5 kW at 6 GHz yields a 5‑MHz baseband with 40‑dB SNR, and the same system can support other frequencies or paths.
The existence of artificial earth satellites and of very low-noise maser amplifiers makes microwave links using spherical satellites as passive reflectors seem an interesting alternative to cable or tropospheric scatter for broad-band transatlantic communication. A satellite in a polar orbit at a height of 3000 miles would be mutually visible from Newfoundland and the Hebrides for 22.0 per cent of the time and would be over 7.25° above the horizon at each point for 17.7 per cent of the time. Out of 24 such satellites, some would be mutually visible over 7.25° above the horizon 99 per cent of the time. With 100-foot diameter spheres, 150-foot diameter antennas, and a noise temperature of 20°K, 85 kw at 2000 mc or 9.5 kw at 6000 mc, could provide a 5-mc base band with a 40-db signal-to-noise ratio. The same system of satellites could be used to provide further communication at other frequencies or over other paths
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