Wifi Extender/Repeater for Outbuilding

simonprr · 25 Jan 2012 at 02:39

Hi,

I'm looking for a good Wifi Extender/Repeater to extend a friend's existing wireless-G from an old D-Link router to an outbuilding 20-30 metres away. The house where the router is has that new insulation with silver foil in the walls and so does the outbuilding. I think that is affecting the signal partly at least.

I've tried to extend the range with a cheap TL-Link wireless-G £20 extender which did extend it to just outside the outbuilding, but as soon as you are inside it's gone. That was with the extender on the window sill in the house closest to the outbuilding too.

So would something like this:
http://www.overclockers.co.uk/showproduct.php?prodid=NW-030-TP
do the job?

Any suggestions?

Was also thinking I could replace the antenna's but these routers and repeaters etc never say what DBi the existing antenna's are so not sure if it would make any difference. I saw a few cheap 9 DBi antenna's which I hope would help, difficult to say if they would though!

Anyway, any help/comments appreciated.

Thanks

bremen1874 · 25 Jan 2012 at 03:12

A directional antenna, preferably mounted externally could work.

No chance that you could use some external grade network cable and hard wire it?

It’s probably also just about within the range of powerline adapters. This would obviously depend on many local factors.

simonprr · 25 Jan 2012 at 14:13

Thanks for the reply

Is a directional antenna simply an antenna that only sends the wifi signal in one direction in a straight line?

My friend doesn't want to hard wire it because of gardens in the way and also a driveway so difficult to go under and on top looks untidy and can get damaged.

We tried powerline adapters, the power is split under the ground so completely different switch/fuse boards.

In theory the signal only needs to be boosted a little as I can pick it up right next to the outbuilding its just inside I loose it. Although I know that getting through a wall is more difficult.

Do you happen to have any idea what a "normal" wifi antenna is in DBi? I found something that said they are usually around 2 DBi but not sure if thats correct or not. Plus what kind of DBi would be required for a directional antenna?

tezabeza · 25 Jan 2012 at 15:30

simonprr said:
Thanks for the reply

Is a directional antenna simply an antenna that only sends the wifi signal in one direction in a straight line?

My friend doesn't want to hard wire it because of gardens in the way and also a driveway so difficult to go under and on top looks untidy and can get damaged.

We tried powerline adapters, the power is split under the ground so completely different switch/fuse boards.

In theory the signal only needs to be boosted a little as I can pick it up right next to the outbuilding its just inside I loose it. Although I know that getting through a wall is more difficult.

Do you happen to have any idea what a "normal" wifi antenna is in DBi? I found something that said they are usually around 2 DBi but not sure if thats correct or not. Plus what kind of DBi would be required for a directional antenna?

The standard small antennas that you get with WiFi gear are as you said 2dBi now this may sound good but there real gain is less than 0dB!! as dBi is Gain over an Isotropic Radiator in other words the perfect radiator and in the real world you don't get that. So it's real dB gain is -0.85dBd !!!!! dBd is Gain over a Dipole antenna.

The use of a directional (Yagi) antenna on the router will really boost the signal to the out building BUT you also need to boost the signal from the WiFi Card in the PC. And the higher gain 5dBi or better will do that for you. But if you can get one for the PC in the out building too then you will have MAX signal as most directional yagis are around 15-18dbi. Just replace the antenna on the PC with the cable from the directional antenna and point both antennas at each other, MAX SIGNAL and MAX SPEED!!!!

Bear in mind that these antennas will give you a good distance of over 1 mile in clear paths!!! so the 30m or so will be a easy path for them.

If you can get the router near the window of the house you should be able to get away with RG-223U coax at 1.5-2m in length MAX anything longer you start needing cables that are much thicker of 10mm diameter and will probably hold the router off the shelf or what ever your sitting it on

Don't forget that if the router and PC card are N WiFi cards that you will need 2 as there is an antenna for receive and one for Transmit. And if its a Dual Band system 2.4Ghz and 5Ghz then your going to need 3, as you will need one that does the 5Ghz band too.

Hope this helps

simonprr · 25 Jan 2012 at 16:34

Thanks tezabeza, thats really useful. Hope you don't mind a few more questions!

I think I understand what you mean about the gain... but not sure why it changes from dBi to dBd? Also how can you have minus gain? Surely that would mean no gain at all (or impossible)!?

I've actually found that some of those TL-Link Wireless N APs have gain of 4 dBi. Would this mean they would actually have a positive/better gain?

I've seen that TP-Link do what I need I think: "TL-ANT2409A 2.4GHz 9dbi Outdoor Directional Panel Antenna". Would 9dBi be enough? They do one thats 14dBi but thats a bit pricey. Also would it matter if the antennas were in the window, or do they have to be outside?

I should have said that my friend doesn't really mind about performance as long as it's good enough for a bit of email/internet browsing. So 2.4Ghz wifi B/G is fine.

So a repeater or router that has 3 antenna is because:
1 x 5Ghz send (wifi N)
1 x 5Ghz receive (wifi N)
1 x 2.4Ghz send and receive (wifi B/G)
Am I right?

In that case I would only have to upgrade one (I hope).

Would I definitely have to have another antenna in the outbuilding? This is a bit difficult as it's probably going to be used for smartphones and laptops where you can't connect antennas. So maybe I'll need another repeater in the outbuilding?

Thanks again for your help

tezabeza · 25 Jan 2012 at 17:46

Simonprr,
Yes you can have a -dBi as this is called LOSS. The 2dbi antennas arnt the best as you can see.
The 3 antennas that most of the new dual band / N routers are there because there is:-

1 x 2.4Ghz Transmit
1 x 2.4Ghz Receive
1 x 5Ghz Transmit/Receive

You have 2 antennas on 2.4Ghz because part of the N spec is whats called MIMO this means that in long and short terms the 2.4Ghz unit is FULL DUPLEX in other words it can transmit and receive data at the same time, this is because it uses two different channels.

The antennas don't have to be outside to work but will work much better if they are as the signal will not be attenuated as the signal doesn't have to pass through anything. And don't forget that if the antennas are looking at each other through the walls or structure at an angle then the structure will appear much thicker as it sees a much larger cross section of material.

Regarding the dBi and dBd thing the difference is explained in the previous post they are representing two different mathematical version of the radiator. The DBI is only theoretical it doesn't really exist this is where the dBd is different it is the ACTUALL measured gain of the antenna and GAIN is good it make the signal stronger. There is 2.14db difference between dBi and dBd this is why ALL the manufactures give it in dBi as it in theory higher than dBd BUT only in THEORY all a sales gimmick really.

SO
DBi is Gain in reference to an ISOTROPIC RADIATOR or a THEORETICAL antenna
dBd is Gain in reference to a Dipole antenna which is a REAL ANTENNA!!!!

If your a dab hand then if you do a search on google for a WiFi BOWTIE antenna you may be surprised just how easy it is to MAKE one!! or how ever many you need.