Quote:
Originally Posted by hawhill
Well, I've got a mini-pcie-slot, USB wifi card right here on my desk. However, However, I don't have an antenna yet...
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2.4 GHz wifi frequencies have a quarter wavelength almost exactly one inch (25.4 mm).
You can make an extremely simple quarter-wave whip antenna by stripping a small amount of insulation off one end of a piece of small wire and poking the stripped end into the wifi coax connector. Then measure and cut the wire so that only one inch (25.4 mm) extends from the connector. You do not need to strip the rest of the wire (only the part inside the connector).
This works surprisingly well. I have done it many times.
EDIT: A better antenna is a dipole antenna. You can make one from a short piece of coaxial cable (50-ohm preferred, but 75-ohm TV cable works fine if kept short).
Cut a couple inches or so (about 50 mm) of the outer insulation off the outer braided metal shield. Then push back the braided shield to open the weave and loosen it, and roll the braided metal shield back over the remaining outer insulation. Trim the rolled back shield to one inch (25.4 mm). Trim the remaining insulated conductor wire to one inch (25.4 mm). Do not strip the insulation off the inner wire. Wrap plastic insulating tape around the outer shield to keep it from shorting out anything nearby. This works a lot better that the simple quarter-wave whip described above.
Either antenna is extremely simple to construct, and they work well if the distance is not too far from the wifi router. I have made plenty of these too (even for long term use). If careful, you can strip and spread the braided shield on the other end too, stick the center wire (stripped) into the a coax connector, and wrap the outer braided shield wire around the outer metal part of the coax connector. Extremely cheap and expedient "MacGuyver" antenna hacks.