Router antenni - Does it matter where they point?

[Daffy D]

WiFi Routers have at least one or more usually several antenni, so does it make any difference to signal strength depending on where they are pointing.

 

Most pictures of router set up shows the antenni standing straight up. Presumably this gives a good general all round signal, but what if you wanted stronger signal in a certain area would pointing the antenni in that direction give you a better signal in that area?

 

Just curious 

 

 

Edited November 25, 2016 by Daffy D

[carlyai]

I'm just embracing this modern technology again, and will probably be corrected, but here is my take.

Modern routers use time and frequency multiplexing, I think.

Frequencies fade at different rates. If you have many aerial that are space related ie separated from each other, then you can pick the best signal from an aerial (antenna), and use that signal. So if you have a very fast switch, sampling the antenna signals, you can have the best output signal. There is an internet standard that has defined the best number of antennas on a router.

Radio transmitted microwaves are electromechanical waves; if you see antennas on top of cars, they are vertically polarised , so to reciever a signal you need your aerial mounted vertically. If you have an old TV antenna it looks like it is flat with respect to the ground, so it is horizontally polarised .

In theory, to get the best signal, you either have the aerial horizontal or vertical, but with microwaves (small wavelength waves) that are used with wifi, you get absorption and reflection from walls in your house etc, so you can place the router antenna anywhere to get the best signal.

Sent from my SM-J700F using Tapatalk

[KhunBENQ]

Never thought about it thoroughly.

I just made sure that the router has an elevated position not to close to the wall and no other devices.

Both antennas vertical (as most would assume to be the only "best").

In the internet you find some sites swearing that perpendicular is best (one vertical, one horizontal).

I really don't know whether it's true

 

But why not try it and do exact measurement (if you have a PC or laptop with Windows?).

Since long I used programs to measure WiFi parameters.

One was commercial trialware expired, skipped

But there is an open software named "Vistumbler" that does the job.

https://www.vistumbler.net/

 

Just did a run on my laptop (disconnect cable from the gigabit router and let it connect via WiFi). The signal is close to ideal here on the upper floor. Also I have one high gain antenna (+9 dB).

That's why you see "-46 dB"/"-45 dB" in the RSSI columns, a very strong signal.

The second entry is a same name SSID from a WiFi repeater in the basement.

The closer the absolute value to zero the better.

-90 dB is at the edge of usability.

The program does endless more stuff (columns). See on your own.

 

So now you can run the program and fiddle with antenna and router position.

 

click on picture to see full size.

 

 

BTW: these four entries are all I see in my village neigborhood.

Try this in a Pattaya or Bangkok condo

[carlyai]

Now opening a can of worms: Respectfully, the signal is in dbm not db.

Dbm is a reference level to something.

So, if you have a signal level of -45 dbm then you know it is referenced to a certain thing.

If you say your signal is -45 db, then you don't know what the reference signal really is. If -20 db is the normal signal, then if you reference to this then -45 db referenced to - 20 is only 25 db. I think. ?



Sent from my SM-J700F using Tapatalk

[carlyai]

Thanks for the link. [emoji4]

[Crossy]

43 minutes ago, carlyai said:

Now opening a can of worms: Respectfully, the signal is in dbm not db.

Dbm is a reference level to something.

So, if you have a signal level of -45 dbm then you know it is referenced to a certain thing.

If you say your signal is -45 db, then you don't know what the reference signal really is. If -20 db is the normal signal, then if you reference to this then -45 db referenced to - 20 is only 25 db. I think. ?

 

 

Careful Carl, the symbol for decibel (Deci-Bell, a tenth of a Bell) is dB.

 

Adding the 'm' gives a fixed reference, but relative measurements you don't really need it.

 

A change of -6dB is the half power point, so -46dBm is half the signal strength of -40dBm.

 

 

[carlyai]

Ahhhaaa,

6db voltage.

3db power.

[emoji39]

Sent from my SM-J700F using Tapatalk

[Chicog]

Install Wifi Analyzer on your Android device, set it down and play with the antenna.

[Crossy]

12 minutes ago, carlyai said:

6db voltage.
3db power.

 

Actually -3dB power, - 6dB voltage (I got 'em the wrong way round, it's been a very long time). And it is power we are interested in with RF signal strength.

 

The case of the units is important, you can safely get hold of 20mV, 20MV will vaporise you

[carlyai]

No excuse...I'm taking back one bottle out of the 10 cases I owe you. [emoji41]

Sent from my SM-J700F using Tapatalk

[Crossy]

Touché :)

 

[KhunBENQ]

21 minutes ago, Chicog said:

Install Wifi Analyzer on your Android device, set it down and play with the antenna.

Over lunch I tested WiFi analyzer by farproc.

The visualizations are nice.

Dependency on the position of the phone is quite big, removing protective cover, touching here, touching there.

 

[Chicog]

That's why I said "set it down".

 

[Daffy D]

My limited knowledge of radio signals and aerial positioning is from the days before all this " frequency multiplexing" stuff with and computer WiFi .

 

I seem to remember that both the transmitting and the receiving ariels should be in the same plane, vertical or horizontal for the best signal and by having a pair of ariels, like a truckers twin CB rig will direct the signal along the highway. Which is want you want on the road, and not so much radiating out in all directions.

 

With home WiFi it does not seem to matter what the orientation of you computer or laptop is as the only ariel you see are on the router.

 

Testing signal WiFi strength round the house will give you the best and worst reception areas, but is this due to the positioning of the antenni or just the walls and furniture that getting in the way?

 

[KhunBENQ]

23 minutes ago, Daffy D said:

 

Testing signal WiFi strength round the house will give you the best and worst reception areas, but is this due to the positioning of the antenni or just the walls and furniture that getting in the way?

For the signal strength the position of the router, walls/windows/furniture AND quality/gain/positioning of the antennas all might play a role (and of course the quality of the device's receiver).

In areas with strong signal the difference from positioning of the antenna will hardly be measurable.

So find an area with a low signal (e.g. -70 dBm) and then try to improve by directing antenna.

 

Do you have a practical problem/scenario with WiFi reception within the house/plot?

Do you live in an area with many WiFi hotspots/users?

 

 

 

[Pib]

Using just pointing the antennas straight up is usually best...basically they are broadcasting a very fast donut pattern.  You can tilt them a little to see if it makes much of a signal strength difference.   Use one of the many available apps to monitor the actual signal strength change and connection Link speed change.  When the dust settles you probably won't notice much of a difference in positioning of the antenna.

 

The biggest three things that affect your signal strength & speed are:  (1) distance between the router and your devices, (2) obstructions like walls/floor, and (3) Wifi interference from your neighbor's Wifi routers.   The later affects the 2.4Ghz channels much more than 5Ghz channels and it can vary greatly from minute to minute as the interfering signals go in and out of phase with each other which has the impact of varying your signal strength and speed.

[Chicog]

If you want to see what channels are in use, an app called Wifi Overview 360 is quite good for that.

 

 

[RichCor]

As Pib noted, the WiFi signal is propagated in a donut-like shape emanating from each antenna.  (Picture an antenna placed up through the center of an actual donut, then inflate the donut until it fills the space surrounding the antenna).  Be aware that some physical surfaces that are dense or metalic will absorb or reflect the inflated donut.

 

Also, if the antenna has a dBi 'gain' then the electro-magnetic pattern it sends/receives has been altered to have a farther 'reach', usually in the horizontal plane while sacrificing sensitivity in the extreme vertical planes.  (Think of a squashed donut, now wider but flatter). Some WiFi routers offer the ability to replace the antennas with higher-gain models ...just know that the higher-dBi gain antennas turn your already squished donut even more flat to reach further in the horizontal plane and have less ability in the up/down vertical plane. 

 

Placing the WiFi Router in a centralized location will help better distribute the send/receive ability of the router.  

 

If you occupied a multi-floor shophouse then you might be better off placing the WiFi on a mid-level floor and setting the antennas vertical so that the imaginary squashed donut inflates in the up and down to cover the floors above, below and mid. But with all that concrete cement and iron rebar you might be better off running additional LAN cables and use dedicated WiFi Access Points covering their own floor.

 

WiFi Access Points with N and AC protocols utilizing multiple antennas sometimes work better/farther as they are quickly able to analyze the signals each antenna receives compared to its time-based physical location, extracting more usable/reliably-correct data. The multiple antennas should be placed in the same operating position/plane in sync to better detect higher-speed data. 

[AgentSmith]

Long story short, here is my simplified view on wifi antennas. All those short default antennas on access points are omnidirectional with 0 or little gain. This means they transmit in a more or less perfect sphere meaning no directing is required when it comes to signal strength. For polarization reasons if you have 2 antennas position them in a 90 degrees V shape. If you have 3 then position them in a W shape. In my experience they transmit the best when pointed away from the wall if the access point is wall mounted. In my case the 2 antennas are in a V shape in a horizontal plane, perpendicular to the wall.

 

I don't like higher gain antennas because of wall penetrating signals. In the area here there are lots of signals coming from the neighbors. The whole 2.4 GHz spectrum is flooded with all sorts of networks. Luckily there is 5 GHz nowadays which barely goes through walls. I call that a blessing in disguise and people should learn not to try to reach all corners of their houses with just one access point. Instead simply install several weaker AP's to get full coverage without having to 'pollute' the area around your house. The added safety (it makes it a lot harder for outsiders to hack your network) is a nice bonus.