Long Range WiFi Antenna
Most wireless cards inside computers, or adapters plugged into computers, have pathetic antennas. Most of the time that's OK though because they are only trying to network over a distance of a few meters. But if you want to go long you need an antenna with more gain. This design has about 17 db of gain, so it provides about 50x the gain of an isotropic antenna. Here's the finished product mounted on a tripod.
This helical antenna has great directivity, it's pretty rugged and reasonably compact, about 16" long.
The antenna signal passes through a very short section of Teflon dielectric coax and right into the USB adapter. A reasonably long USB cable (say 5 meters) will then carry the signal to the computer. Running the RF all the way to the computer without first making the conversion would be far more lossy and hence defeat the purpose of the antenna.
If you're interested, here is some computer generated design data for this antenna.
Test result coming soon.