A rooftop television antenna, sometimes called a "yagi" antenna, can be modified for use with a wireless Internet network card. While the antenna's waveform is not ideally suited for the Wi-Fi radio band, the outdoor, high-mounted metal structure will have a noticeable performance increase over standard rubber mast antennas. Many rooftop antennas also have a motorized mount, which allows them to be turned toward a strong signal. The average experimenter can adapt a yagi antenna for use with Wi-Fi in about 20 minutes.
Isolate the antenna cable being used from other nodes in the home by removing them from the junction box, or using the wire stripping tool to cut them. Many rooftop antennas have multiple cables linked to different rooms, coming together at a junction box near the primary lead that runs to the antenna. If this box is not accessible, cutting the cables close to the box is acceptable, but it will permanently destroy the antenna infrastructure. Replace the junction box with a coaxial coupler, if possible.
Attach the N-type cable adapter to the coaxial cable lead by threading it into the plug and turning it clockwise until it is tight. Splicing the cables together is possible if an adapter cannot be found; cut and strip the cables, then twist their cores and shielding together. Wrap the connection with a liberal amount of electrical tape. Splicing the wires could reduce the effectiveness of the antenna by creating a small load at the splice point, however negligible.
Attach the Reverse-SMA to N-type adapter by re-splicing the cable's positive leads, with reversed cores. Cut and strip the center of the adapter cable with the wire stripping tool, then cut the cable completely in half. Strip the shielding away from the core, and remove the soft core insulation to leave 1/2 inch of exposed core. Attach the core wire of one side to the shielding of the opposite side and twist them together. Attach the remaining core to the open shielding of the opposite side, and cover all exposed metal with electrical tape. "Reversing the cores" is necessary because R-SMA cable has a negative core, while normal N-type and coaxial cabling has a positive core.
Attach the R-SMA lead to the antenna jack on the wireless networking card or device. Turn the cable's plug clockwise until it is locked in place. If the device is a router, then detach the R-SMA reversed core adapter and simply plug the N-type adapter into the antenna jack (on most wireless routers), and turn clockwise to secure. Using a router may help find distant networks, as many routers have more available transmitting power than the average wireless networking card.
Use the computer to connect to networks in range of the outdoor antenna. If the antenna is motorized, or can be turned, try different positions to find the most effective setting.
Things You'll Need
Wire stripping tool
Reverse SMA to N-type adapter (female R-SMA)
N-type to co-axial adapter (optional)
Co-axial extension cable
Unplug the antenna from the computer or router during lightning storms.
Use extreme caution when cutting or altering the antenna cable system, many coaxial cables used for satellite and cable TV look exactly the same. Follow the cables or test them to ensure the correct one is altered.