Using a Sky or Sat TV dish to pick up wifi signal

[KAL]

If there are any wifi techies out there...

I have a Netgear dual band range extender (AC750) but the omni-directional antenna it comes with is insufficient to pick up a strong enough signal from the access point.

Would it be possible to use a Sky or Sat TV dish as an outdoor antenna to pick up a wi-fi signal, which I could then plug into the antenna port via co-ax? The dish would be mounted ashore.

I have seen aluminium parabolic wifi antennas for sale (e.g. these) but as I have a spare Sky dish sitting about, I wondered if I could use it instead.

Any good?

 

[Tempus]

I'm not sure about the technical details of a Sky dish. However a WIFI attenna needs to both transmit and receive as Wifi is a 2 way communication, unlike receiving satellite which is one way, so I'd be very doubtful. I'd also be surprised in a parabolic wifi antenna would work well on a boat as the focussed beam would not respond well to movement. We have an 8gb omnidirectional attenna mounted on a ubiquiti bullet on the backstay, this picks up the wifi signal and then plugs into a LAN port on a standard router in the cabin, which broadcasts another signal around the boat. This type of system, or a similar set-up from Alfa seems to be the best bet.

 

[Davy_S]

It can be done, in fact a couple of years ago a wifi signal was sent from Kefalonia to Patras, a distance of around sixty miles, a usb wifi stick was placed at the centre of the dish, replacing the Lnb, from what I recollect it was done for test purposes only ( I cannot remember the size of the dish) I tried it myself over a distance of 3 miles, it was not as good as my directional wifi antenna, which is about one foot square. This easily picked up usable wifi from three miles, perfect line of sight. It does sound feasible, but in practice the directional antenna is better IMHO.

 

[VicMallows]

Short answer: NO ...... unless you want to get seriously into RF antenna design.

Even then a very high gain antenna always means a very narrow beamwidth. (the antenna must point in precisely the right direction and must remain static). Not exactly practicable on a boat.

 

[nigelmercier]

Quite feasible, in fact you can use a Pringles tin (Google it). Note that the OP plans to mount the dish on land.

 

[KAL]

Quite feasible, in fact you can use a Pringles tin (Google it). Note that the OP plans to mount the dish on land.

I'm willing to give it a go if I won't risk blowing anything...

Almost complete ignorance admitted! Can I use the LNB that came with the dish and (allowing for the correct co-ax fitting) plug the co-ax lead into the receive antenna port of the range extender, or do I need a different LNB, power, etc.

Sorry to be so basic in my questioning.

 

[Danbury]

I get an extra couple of bars signal from my 3g dongle just by sticking a parabolic shaped piece of tin foil behind it. You need to get the distance right, but that's just trial and error...

 

[Tempus]

I'm willing to give it a go if I won't risk blowing anything...

Almost complete ignorance admitted! Can I use the LNB that came with the dish and (allowing for the correct co-ax fitting) plug the co-ax lead into the receive antenna port of the range extender, or do I need a different LNB, power, etc.
.

you certainly won't break anything if you try. However I'd be certain that you need a different LNB as you need to transmit. Also be aware that wifi is a very weak signal, particularly compared to tv or sat, hence most wifi gear has the transmitter/receiver connected directly to the aerial. Loss of signal along cable runs is a big problem.

 

[SimonFa]

As has been said elsewhere there a real technical involved to get the right antenna sizes for the dish. Anyway, your biggest problem is one of legality.

The maximum power (EIRP) that you are allowed to transmit is 100mW (20dBm). This is calculated by taking the power output of your wi-fi transmitter in dBm, subtracting any cable losses (dBs) and then adding the gain of the antenna in dBi (i=isotropic if it is in dBd (d=di-pole) add 2.2dB for conversion))

Without looking it up I'm sure you device is already at the limit so any extra gain you get would make you illegal. Ofcom may or may not find you but they do take a very dim view of these things because you are polluting everyone else's wi-fi spectrum.

PS All those techy terms can easily be found on wiki or elsewhere. I can provide more background if you wish.

 

[SimonFa]

I get an extra couple of bars signal from my 3g dongle just by sticking a parabolic shaped piece of tin foil behind it. You need to get the distance right, but that's just trial and error...

Just because you appear to have more bars it doesn't follow that you will get any extra throughput and you could be making it worse.

3G works best when their is no interference (high signal to noise ratio) as it can use high modulation schemes. So whilst you might get the illusion of a stronger signal you may well be increasing interference and hence throughput. However you may also be reducing interference if it is coming from behind you tin foil.

I'm not saying you shouldn't bother, just don't expect it to always work.

 

[nigelmercier]

You remove the LNB and mount the Wi-Fi antenna in the same location. Some adjustments will be needed for maximum gain.

 

[VicMallows]

Note that the OP plans to mount the dish on land.

Where does he say that?

Edit: OK 'The dish would be mounted ashore.'

 

[MM5AHO]

The distance records for WiFi are now into the hundreds of km
http://www.cnet.com/news/new-wi-fi-distance-record-382-kilometers/
http://www.engadget.com/2007/06/19/venezuelans-set-new-wifi-distance-record-237-miles/

Extending the range can be done very technically, like in these links, or very simply as others have mentioned.
Biscuit tin lids, chocolates tins and all manner of devices have been used to get a little extra gain.
In most cases people are trying to extend just a little bit - where the signal is weak or "nearly there". In such cases the reflector behind the WiFi device often works enough to get a usable signal. Purity of RF design isn't required for just a little gain.
I know some kids who "stole" WiFi across a city while studying at Uni, 4 years of free Internet. Nowadays people are more careful about passwords. They used a biscuit tin to get 1km.