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A comment on Wi-Fi Alliance Brings Wi-Fi 6 into 6 GHz. Parent comment

Re:Wi-Fi Alliance Brings Wi-Fi 6 into 6 GHz by enjenye on Monday January 06, 2020 @02:41AM (#21967317)
Indeed : radio transmissions follow Friis equation [1] -- power decreases by the square of the frequency (same goes for distance). So, going from 2.4 to 5 GHz cuts the received power at a certain distance by a factor of 2 (more or less). Assuming free space, of course : obstacles will make matters worse, depending on frequency, thickness and materials.

Meaning that going from 5 GHz to 6 GHz will decrease the range by a factor of around 1.2

[1] https://en.wikipedia.org/wiki/Friis_transmission_equation

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Re:Wi-Fi Alliance Brings Wi-Fi 6 into 6 GHz by henrikeh on Monday January 06, 2020 @03:39AM (#21967599)
Take note that Friis transmission equation is extremely misleading, since it makes certain assumptions about the choice of antenna, which are not necessarily true for all systems.

Too ask the pointed question: Why would propagation in free space be affected by the frequency of the field?

A good explanation is here: https://www.dsprelated.com/showarticle/62.php

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Re:Wi-Fi Alliance Brings Wi-Fi 6 into 6 GHz by Reventlov on Monday January 06, 2020 @03:13AM (#21967468)
As you note, it's only true when you assume free space. In practice, you have air, you have obstacles, you have earth curvature, you have […], which makes it wrong, because athmosphere has an opacity that varies with the frequency (or wavelength): https://en.wikipedia.org/wiki/File:Atmospheric_electromagnet...

So, no, it's not an universal rule.

Please also note that shorter range is not necessarily bad: it means less interference from neighboring devices that use the same frequency band ( https://www.embedded.com/why-60ghz-mmwave-is-moving-into-the... ).

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