Wireless router placement - high or low

Question

I want to improve the connection to my wireless router and started experimenting with the placement of the router in the room. I am perfectly aware of the fact that lots of things can interfere with it so for this exercise let's assume that the wireless router is placed in a perfect room. My only question is: is it better to place the router higher (near to the ceiling) or lower (near to the floor)?

When placing the router higher I observed these numbers (measured with inSSIDer Home):

Signal: -42 to -45 dBm Link Score: 72-78

When placing the router lower I observer these numbers:

Signal: -29 to -31 dBm Link Score: 86-91

I understand that a higher link score is better but then I read a lot of posts and articles where most of the time it is suggested to place the router higher.

One other thing to consider: the devices that are going to be connected to the wireless router will be held at normal height (1-1,30m).

Answer 1

From what I've read in a CWNA training book: You want your antennas to all be the same direction. Because some laptops may use internal antennas on the upper half, with the screen, and because screens are normally vertical, you want all antennas to be vertical. If you have sideways antennas, it causes polarity issues which degrades the signal significantly.

Therefore, having the antennas higher or lower would mean non-horizontal communications, which are non-perpendicular to the antennas, and are less than ideal. If you mount a receiver on the ceiling, with antennas pointing down (instead of up), that's still vertical, which is desirably perpendicular to the horizontal airwaves sent out by other vertical antennas.

If you can't have your receiver be mid-height, then higher is probably better than lower, just because of the likelihood of less interference/blockage from objects. Of course, that is just a generalization, and is likely to be false if there is a reason why higher is bad (like being closer to another source of interference).

Wireless can be a funny thing, due to factors like changing technology, improving standards, and changes that can be made to an environment (like new sources of radio interference, or new furniture that suddenly has an unplanned impact on airwaves). Any specific advice (like whether higher or lower is better) is probably prone to not work well in some circumstances. So if you try something specific, and it's working well, I would run with that.

You do want link. So a higher link score is probably a good idea.
I just read recently that some of the settings that people used to tinker with (power levels), for older equipment, are not typically supported by the newer equipment. As new technology comes out, perhaps especially with newer standards (like 802.11ac vs. 802.11n), any rules that are given are probably subject to change. If your driver gives you a "link score", I would be inclined to trust that as the best simple advice you're going to get.

Answer 2

The answer depends on the aerial, but I'd suggest mid way up the room for the following reasons -

1. Fresnel clearance for 50 meters at 2.4 gigs is about 1.2 meters - a Standard room is about 2.4 meters, so half way, so the closer to the ground or ceiling the more waste.

2. Beams are generally radiate out in a way which is flattened in the vertical direction - and the more the antenna gain, the flatter this shape will be (assuming, of-course, the use of an Omni directional aerial).

I'd imagine the logic of placing an antenna higher is that it is more likely to have line of site to computers.