Abstract
There is a proposal to transmit messages to mobile telephones in large U.S. cities from a transmitter suspended below a balloon at an altitude of 40 km . Suppose the city in question has a diameter of 40 km. What is the solid angle to be illuminated? Suppose mobile telephones require an electric field strength, E, of 200 μV per meter. If one uses S = E 2∕R with R = 50 Ω, what is the E field at the transmitter? How much power must be transmitted? At what distance from the transmitter would the microwave radiation reach the danger level, 10 mW cm−2?
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Wilson, T.L., Hüttemeister, S. (2018). Electromagnetic Wave Propagation Fundamentals. In: Tools of Radio Astronomy - Problems and Solutions. Astronomy and Astrophysics Library. Springer, Cham. https://doi.org/10.1007/978-3-319-90820-5_2
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DOI: https://doi.org/10.1007/978-3-319-90820-5_2
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