How can I beam my Wifi signal across the street?
Is it possible to boost a wifi signal enough to be received from +/-500m away and through buildings/trees?
Ok, I know this has already been answered 3 times already, but I think this deserves a good summing up and clarification.
To boost the signal of your WiFi you basically have three options:
1: Wireless Repeater
If you have access to points in between the source point and the target point you can use one, or a chain of, Wireless Repeaters. These connect to the existing wireless signal, much like a laptop does, but then they send out a new signal extending the range of the wireless coverage. These operate best when sited far enough away from the previous access point in the chain as possible whilst still having enough signal strength to prevent transmission errors.
2: High Gain Antenna
Replacing the normal antenna on a WiFi device with a high gain one can massively increase the range of the signal. These are actually misleadingly named, as they do not increase the actual signal strength, but instead change the shape of the signal, squashing it flatter but longer.
The signal travels further at the cost of flexibility. It is far easier for a receiver to fall below the level of the signal .
3: Parabolic or Wave Guide Antenna
These are a special type of antenna specifically for sending a signal from one point to another. Parabolic Antennae are basically satellite dishes, and work on the same principal. Wave Guides work by shaping the signal into a beam through the use of specifically designed and measured tubing. There have been many home projects involving making various types of wave guides out of such household objects as Pringles cans, and other metallic canisters. These have had some quite surprising results and fall broadly into 2 categories: Traditional Wave Guides (a pringles can and a short length of copper wire) and a Yagi Array (A can with a number of specially spaced metallic disks inside, or a TV Aerial style antenna).
As with any wireless link to a remote site it is best to keep it separate from the wireless that covers the main site - simply because boosting the main site signal to encompass the remote site may cause the main site to have problems with the signal - and narrow the link signal down as much as possible. It also reduces your wireless footprint and reduce the chances of interference.
How far a signal can actually travel is dependant solely on the medium it has to travel through. As the WiFi (2.4GHz) signal is at, or around, one of the harmonics of the resonant frequency of the Hydrogen atom, anything with a high water content reduces the signal considerably. This is why your satellite signal goes screwy when there's to much cloud and rain. Trees contain a lot of water so they attenuate the signal a considerable amount. You may not think it, but buildings contain a considerable amount of water; not in its liquid form, but present in the concrete and cement and bound there as part of the chemical reaction that hardens it.
You will need a WiFi Repeater, this allows you to extend the range...
Whether this works for buildings depends on the size of their walls, you more likely want to set up a VPN.
If you can't place a Repeater, you will need a better antenna or router to boost the signal.
You could try a parabolic booster like this one. I don't know if it would increase your range sufficiently, but it's nearly free and worth a try.
From some testing, a standard 3db antenna such as is shipped with many access points, and a signal output strength of 100mW, I managed to consistently get over 1km line of sight. Using a directional antenna, such as a Huber Suhner long range antenna can dramatically increase this.
That said, to get through trees is difficult - they really attenuate the signal, so a repeater is essential.