This is little bit of info about the ~6dBi WiFi Antenna I have built. All up it took me about 2 hours to make and build the Antenna. All that is left to do is test the Antenna to see how good it works and that it is on frequency.
The materials required:
- approx 300mm 1.6mm copper wire
- panel-mount female N-connector
- 250mm length of 20mm light-duty electrical conduit
- 2 end-caps to suit 20mm conduit
This collinear simply consists of a length of copper wire with some loops located at specific locations. The dimensions of the sections of the antenna are important, and are shown in the diagram below.
Image sourced from martybugs.net
The length of the bottom section is 1/2 wavelength, the centre section is 3/4 wavelength, and whip section on the top is slightly less than 3/4 wavelength, apparently to reduce the capacitance effect.
The 802.11b standard uses 2.412MHz to 2.484MHz frequency range, so at the centre of that frequency range, 1/2 wavelength is 61mm, and 3/4 wavelength is 91.5mm.
These dimensions appear to be consistent with similar commercial antennas.
Home-brew Compact 6dBi Collinear Antenna