Wifi over distance.. Or how to make mistakes..

My mate Ralph just moved into a new house - one that he built (almost) himself, and it was going to take a few months for BT to get the phone line and broadband installed. Screams of discontent from the teenage daughter, etc. So I pitched in and said - "Yeah, we can run a Wifi link from the Farm office over there", vaguely waving about a kilometre or so in the distance.. Well.. This is the story..



First things first. Lets get a Wifi device at the right side of the farm office buildings. Being a farm building, over 50 years old and in Scotland, the walls are about 1m thick. Really. Wifi wasn't even getting between rooms, so first thing was to get 100m of ethernet cable, some sockets (all from B&Q), and Ralph (being a builder) slung the cabling through the roof.


Then I took my aging LinkSys WAP54 Wireless Access point, parked it on the windowsill, optimistically pointed the stubby antennae through the window (and a hedge, some bins and a field full of cows) and at Ralph's house. Absolutely no joy. The signal went about 100m (10%..) and faded. Why?



IMG00039.jpgStandard Wifi devices in this country I believe are limited to 0.3w of power. And they ship with Omni-directional antennae, so you don't have to point something. But that means we end up with a rather small circle of coverage. Soooo. Off to eBay, and got myself a parabolic wire wifi antenna. About £25 each (and another tenner in postage). And they're big. Here's one mounted below Ralph's TV aerial.




IMG00045.jpg

Okay, so what I needed was a cable that went from the back of the Linksys WAP54g device to the antenna. It was supplied with a 30cm flylead - just about enough to get to the pole the thing was mounted in. And I couldnt put the wifi-device on the pole (it was an indoor device, not an outdoor one). Sooo. I ordered 20m of HD400 cable, and what I thought were the relevant connectors. Another £90 in parts and postage.. I receved them, tried to put them together and found that what I thought was a male connector was actually a female connector and so forth. How many dammed connectors did I end up with? The photo shows:



  • The N-Type Male connector at the end of the parabolic antennae cable.


  • The N-Type Female converter to TNC Female converter. The other end is sitting in position three.


  • The more observant will have noticed that its 'threads' are wrong. That is, the screw in part of the connector is wrong - it should have threads on the outside, not the inside. Well, thats because some idiot in a standards committe decided that (1) Its a good idea to have all these connectors and (2) lets use the suffix 'RP' to denote that were going to mess around with how the threads work. So much for standardisation, right?


  • So in the end I had to basically rip the N-Type connector from the antenna, and replace it with a RP TNC 'Male' (next one along). Male in the sense that the internal connector has a socket (eh?) but the outer threads are on the outside (eh?). Oh. Its reversed.


  • There's an example 'cheap' antenna from the WAP54


  • The Back of the WAP54g has a RP TNC 'female'. So thread on the outside, and a pin in the middle.


  • And just in case this all makes sense and your understanding this so far, at the bottom is a NetGear 834G router. As you can see, its a completely different connector again. Sigh.



So as you can see, you need to order the right connectors for your antenna, and your wifi-router. DONT do as I do, try and use logic to figure this out. Use suppliers who provide pictures of the damn things, and if in doubt, call em. I found Wifi-Antennas to be very good in this respect. I should have just ordered everything from them in the first place, and saved a fortune in postage by carpet-bombing eBay.



So far, so good. As I said, I used a LinkSys WAP54G, primarily because I already had one. I got another from eBay for another £25 or so. I then found that setting up these bloody devices to be a nightmare. The manual is here and is about as good as a chocolate teapot. There's a far better cheat-sheet here. The setup boils down to:


  • Set up the one in the office (wired to the existing network) as an Access Point

  • Set up the second one as a wireless repeater, and plug in the MAC address of the other router

  • Switch off Antenna Diversity. The cheat sheet makes the excellent point that if the two antenna are different (and these certainly were - one was the huge parabolic, and one was the stubby standard one!), then the amplifier has a hard time. Switch off the cheap nasty antenna.

And basically, it should work. I've missed out the 'crawling along the loft', 'being lifted by a forklift whilst on a wooden pallet up to the TV mast', 'construct a wall mounting bracket', 'recabling the farm office', etc.



Why are the WAP54G's a nightmare ? It either works, or doesnt. The WAP54g doesnt give a signal strength, so its a real hit and miss. In this case, we had line-of-sight, and both dishes were above the height of the intervening vegetation, cars, and the field full of cows. If it was a longer distance, then we'd have real difficulty setting this up. Perhaps using laserpointers at night would have done the trick.



Some tips if you want to do this better:


  • Find a cheap access point thats easier to set up. I have no recommendations at this point.

  • Outdoor antenna get further. Although you have to mount them to a wall, etc, and use outdoor cable, its worth the effort.

  • Get the Access points configured and up-and-running whilst at your desk. Not, as I did, by driving back and forth a lot.

  • Get the right connectors first time, and if you can, get the shop to make up the leads for you. The more expensive the leads, the thicker the cable and less loss. I tried to do it all myself, and ended up ordering the wrong connectors a few times.

  • I might be wrong, but I suspect a 'standard' access point/router only pumps out 0.3w of energy. I also suspect that there might be a maximum you can push out before the authorities in your country get a little upset. But if its distance your after, then adding a 1w amplifier to either end might easily increase the distance by four or five times..



So there you have it. Standard antenna, home-made brackets (in one case), some cable and connectors, and off-the-shelf/eBay Access points. And at least a 1km link.