Noise in Antennas
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چکیده
Thus far we have examined how to calculate the power radiated from an antenna and, using the Friis transmission formula, how to calculate the received power at the other end of a communication link. However, the received signal power is meaningless unless compared with the power received from unwanted sources over the same bandwidth. Such noise sources include thermal radiation from the earth and sky, cosmic background radiation, and random thermal processes in the receiving system. In today’s wireless environment, additional noise due to nonstationary radio frequency interference from pagers, cellular phones, etc., often needs to be considered, but in this analysis we will concentrate on natural sources only.
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تاریخ انتشار 2001