Figure 24 Attenuation of a 984ft 300m Signal by a Tree

When this sign al e ncounters a tree, the; wavelength of the signal (984 ft/300 m) is so much greater than the size of the tree that the amplitude of the signal remains almost unchanged.


A sharp-eyed reader will look at Figure 2-4 and says "Sure, the amplitude is still large after the col Msion . The am plitude of rlee AM bro adcast si gnal was a lot larger than the amplitude of the 2.4-GHz signal to begin with." Well, sharp-eyed reader, you are correct. Yes, the AM b roadcast signal had higher amplitude ( move power) to begin with—perhaps 50,000W compared to the 2.4-GHz signal that started out with 4W, but here's the point. Even if the AM broadcast signal started out with 4W, a lot more of it wouldstill be left over after encountering the tree, compared to the remaining 2.4-GHz signal. This would be true because the tree is many times larger than the physical wavelength of the 2.4-GHz signal, and the tree is many times smaller than the physical wavelength of the 1000-kHz KWHY-AM signal.

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