A friend of mine wish to set up a long range internet service so he wants to know the things that will be needed. He wants it to cover at least 10Km. Is there any gadget that can convert the normal RJ 45 signals to radio so that it can be transmitted. I need to know More please help.
Radio signal strength is measured in Watts EIRP (look it up in the wikipedia).
WiFi (wireless networking devices) are rated in output power, most are 100mW (100 miliwatts, 1/10th of a Watt) but some high power ones can be gotten that are 200mW.
With the little antennas on them they radiate a pattern that looks like a sphere (ball). By narrowing the pattern, you reduce the area the signal covers except in the pattern itself. This is called a beam antenna.
For each time you narrow the pattern by a factor of 4, you increase the EIRP by 4 and double the distance covered.
The reason I asked where you are, is that in the US, the EIRP limit is 1 watt (10 times normal) for portable devices, but 4 watts (40 times normal) for point to point (from one stationary place to another).
This would require you to have relay stations (look up MESH networks) aproximately every 1.5 to 2 km.
The problem with all of this is that many countries don't have such generous power limits. For example, Israel has a limit of 100mW EIRP.
You may also want to look up WiMax, which is supposed to have a much longer range than WiFi. Before the devices were sold, it was claimed to be as much as
10 miles. Once the first devices came on the market, it was reduced to one mile in practice.
That was a while ago, depending upon how well WiMax actually does, how good your antennas are, what's in the way, it may do the job with one "hop".
Geoffrey S. Mendelson N3OWJ/4X1GM
To help restaurants, as part of the "stimulus package", everyone must order
Line of sight? If yes, very high gain very directional antennas on both ends of a WiFi repeater setup will work well. This is done commonly in cities and from cities to outlying areas where line of sight can be supported. The solution won't be cheap, the WiFi equipment is expensive, as are the antennas and towers. Add to that the cost of setup...
There are a lot of commercial solutions, some pre-packaged. Try Google.