Did anybody ever set up a radio link over a long distance? I want to try to provide a friend of mine propper internet, he lives in a village on the other site of the lake, 5 km away.
Are there directional antennas for linksys or routerboard devices? Tell me your experience!

Try cantenna. Google for pringles, cantenna, and that should give you some help.

do you have Line Of Sight?

Hi.

A couple of years ago, I participated in an experiment as follows.

Place: between Okinawa Islannd and Kudaka Island
    http://www.ocvb.or.jp/card/en/0120290901.html
Distance: over 5km
Device: Buffalo WLA-G54C x2, worked as WDS
    These were attached sma connector for antenna.
Antenna: 15dBi Yagi antenna x2

We pinged from the side of Kudaka to the opposite shore. Packets were returned about 2 or 3 ms average.
I was under the impression that the airwaves had a good condition on the sea.

Sorry to say, We didn't test further. And I don't know about your condition on the lake. You may need more directional antenna.

I hope this encourage you.

regards,

zukky

for the sake of extreme examples i can state that some guy's at wireless-pt.org got a 70 km link at 1mbps... but they did had LOS

* line of sight is necessary, with ample diameter ('fresnel zone') through which the wavefront can propagate. So just over a balcony or roof, or through a slit between buildings is bad news.

* for just 5 km a 1 mtr yagi on both sides will do; you may also use a 60-70 cm parabola with short yagi feed on both sides. Use very short coax cables, or really good quality SHF coax if it has to be longer (e.g. aircom+); a few meters of ordinary TV coax cable or the thin kind used inside wlan routers will cut the energy by half or worse.
To do the 'link budget' in a bit more scientific way have a look here:
http://huizen.deds.nl/~pa0hoo/helix_wif … tcalc.html

* set 'distance' in the radio parameters on both sides to 5000 m (the standard 802.11 protocol timing collapses from a few km onwards and you are left with the minimum 1 Mbps speed); this setting makes the radio wait a a little longer for reception confirmations after having sent something; the radio waves need a tiny bit of extra time due to the distance.

* in a wrt54g(l) the maximum momentary output RF power is about 80 mW; setting it higher may actually reduce performance as the power amplifier saturate and causes distortion which hampers proper demodulation by the receiver. You'll have to reduce it quite a bit to not exceed the regulatory limits; but even when reducing power to not exceed limits the link budget will improve by a better antenna because the antenna gain also helps reception.

If there is no interference, 54 Mbps is totally feasible and ping delays of 1.9 ms. Such a link can transport at ease two 8 Mbps adsl accesses at the same time (useful bitrate in file transfer > 20 Mbps).

Success !

(Last edited by doddel on 14 Jun 2007, 09:14)

I was able to achieve a few long-distance links with with some ISP grade antennas and a very long link with a horn antenna I made out of cardboard and aluminum foil... of course the other end was a WiFi ISP so they would have had better equiptment than I did but the results were still impressive:

http://hastingswireless.homeip.net/inde … p;stage=01

I'm not sure how well your link will work, going over a lake, since the 2.4 GHz band is in the center of the water absorption spectrum (the reason why microwaves use 2.4 GHz).  If your lake has a large number of boats crossing it, try to go for horizontal polarization instead of vertical.  While testing my equipment with GTMC, I noticed a significant drop in signal strength every time a vehicle passed on the road to the south.  When I switched to horizontal polarization, hardly any drop in signal strength was noticeable.

Also, try to make the positioning of your antennas result in little to no chopping of the Fresnel zones... do a little research on what they are and how their geometry looks... they are very important to successful transmission (as doddel alluded to).  The entire Hastings Wireless project died because of all the (deciduous) trees in town absorbing the signal and chopping the Fresnels.

Thank you very much for the infos, but the topic is really hard, for some infos in german I would be really glad.
But, I want not just a 1MBit/s connection, what I want is a 54MBit/s connection over 5km. Is this with a normal Linksysrouter and Cantenna possible? Of course with LOS and fresnel zone.
How can I change the polarization of the antennas?
What is about 802.11a instead of b/g? How much are antennas for these devices.

Offtopic. If I want to set up point-to-point between two houses which are 100-300m far away with antennas (802.11a or b/g) on the roof (LOS): Do I need directional antennas or can I even reach 54MBit/s with normal omni antennas?

(Last edited by fabske on 15 Jun 2007, 09:15)

Maybe you should start with a download from --> http://wndw.net/

Should be able to answe most of your questions ...

allready done

Why not a link of 295Km... at 20mbits! using a 386!

http://www.pianetacellulare.it/Articoli … lo4280.htm

just for fun!

The antenna you use will make all the difference.  I'd recommend either _Parabolics_ or _Yagi_.  I'd tip toward Parabolics, since they have the special function of focusing signal at a narrow region (which is where your receiver will be).  21 or 24dbi Parabolics should do.  Might try: http://www.confero24.com/product_info.p … -parabolic

If that's doesn't cut it, include a booster at transmitter or receiver end (or both!).  Try: http://www.confero24.com/index.php?cName=500mw-boosters

Whatever you do, try not to lose too much signal in to things like cables connectors etc.

Any yes, of all the affordable router-radios out there - Linksys wrt54g(l) products have most powerful output - safe bet.

Good luck! / www.confero24.com