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Physics
Classical Physics
Optics
Diffraction of RF - how is it affected by frequency?
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[QUOTE="tech99, post: 6415706, member: 477979"] Over smooth, flat unobstructed Earth we find that the ground reflection tends to cancel the direct path, and above 30 MHz we usually find that attenuation increases rapidly with distance. Power falls at 12dB when the distance is doubled. In an urban environment, the signal from a high transmitter reaches a mobile at street level via multiple reflections and also by diffraction over rooftops etc. Ths is very hard to calculate, but tests were carried out in Japan by Okumura give reliable empirical data on th statistics of path loss in these circumstances. See Wiki [URL]https://en.wikipedia.org/wiki/Okumura_model[/URL] Diffraction is only one part of the propagation mechanism in the urban environment. If the wavelength is large compared to the obstruction then diffraction is greater. But notice that free space path loss increases with frequency. There are nomograms available giving the approximate diffraction loss over hills and knife edges for cases where we have a clean path. I can find a link if required. [/QUOTE]
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Physics
Classical Physics
Optics
Diffraction of RF - how is it affected by frequency?
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