Question Why 5 GHz WiFi signal is stronger than 2.4 GHz signal?

Nov 20, 2020
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While trying to find the best location for a wireless repeater I have installed WiFi Analyzer app on my Android phone to check signal levels from my dual band router. I was very suprised when I found that 5 GHz signal from my router is stronger than the corresponding 2.4 GHz signal. This made me curious and I started looking at the routers in the neighbourhood. It turned out that my router was not the only one to show this irregular behaviour. On the other hand some other routers 'behaved' as expected - their 2.4 GHz signal was stronger than the corresponding 5 GHz signal.
I wonder if anyone has an explanation to this strange fenomenon?
 
Nov 20, 2020
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Typically 5GHz has a shorter range but isn't as susceptible to lower band frequency interference, ie microwaves and other appliances on the same wavelength.
That is what I have expected, but it turned out that 5 GHz signal from some routers including mine was stronger than the corresponding 2.4 GHz signal
 
Way to hard to tell could be somethings as simple as some tiny amount of metal in the paint on your walls. Could block one frequency better than others. Almost impossible to tell without high end equipment.

Note it takes almost nothing to block these frequencies. Your microwave oven likely puts out 1000 times the power of a router on 2.4g and the amount that is allowed to leak out the door is a tiny fraction of the legal power a router can transmit. You can see though the front glass of your microwave but it is block huge amounts of radio energy.
 
Nov 20, 2020
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Way to hard to tell could be somethings as simple as some tiny amount of metal in the paint on your walls. Could block one frequency better than others. Almost impossible to tell without high end equipment.

Note it takes almost nothing to block these frequencies. Your microwave oven likely puts out 1000 times the power of a router on 2.4g and the amount that is allowed to leak out the door is a tiny fraction of the legal power a router can transmit. You can see though the front glass of your microwave but it is block huge amounts of radio energy.
According to theory 'Free space loss increases with the square of distance between the antennas because the radio waves spread out by the inverse square law and decreases with the square of the wavelength of the radio waves.' (https://en.wikipedia.org/wiki/Free-space_path_loss). This should mean that in the free space the signal propagation loss for 5 GHz signal is 4 times higher than the loss for 2.4 GHz signal. Or am I missing here something? On the other hand are there any evidences that obstacles like walls attenuate the 2.4 GHz signal more than the 5 GHz signal? Rather the contrary.
As to particular spot. I have made 4 measurements on 4 different spots and on all of them for the particular router the 5 GHz signal was stronger and stronger from 5 to 18(!) dBm. You may have a look at the results on OneDrive here: https://1drv.ms/u/s!AsGhargh1fwygVpwdbJbbf3b1HsH?e=QuK7Qh
 
You have to be careful even "air" is not standard unless it is specified. Water vapor makes a huge difference to wifi. On a foggy day the signal levels from a WISP I used to use dropped a lot.

Problem is what are you using to measure. Pretty much anything you can do in your house is not scientific it is purely anecdotal. Go read one of the FCC reports that companies are required to file that show that the signal level conform to the laws. They are massive documents that show all the spacing between the equipment and how the room itself is actually constructed. There really is no way to make any conclusion as to why. It could be any combination of the router, the house and the device you use to test the signals.

Wifi in any house is very very different. In fact the MIMO ability depends on the signal bouncing off different walls and ceilings and taking a slightly different path.
 

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