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Length
The ideal total length of a wire antenna is based on the frequency on which you plan to transmit. The common half-wave antenna is half as long as the length of a radio wave in the frequency band. Use the center frequency of the ham radio band to calculate the ideal length: for example, if you're building an antenna for the 20-meter band, which runs from 14 to 14.450 megahertz, use 14.125 megahertz. To find the ideal length for a half-wave wire antenna for this band, divide 468 by 14.125 to get 33 feet. A full-wave antenna for this band would be nearly 70 feet long, which is impractical for most locations.
Materials
Use sturdy, high-quality materials to build your ham radio wire antenna. Choose a solid -- rather than stranded -- insulated wire with a minimum 14-gauge thickness for the antenna itself. Attach ceramic or glass-based insulators to the ends of the antenna, then use a synthetic rope to connect the insulators to the supports. If you're building a dipole antenna, use a center connector that can take the strain of the antenna wires and the coaxial lead.
Positioning
Install your ham radio wire antenna as far away from power lines, buildings and other structures as possible. Isolating the antenna in this way will increase safety and reduce possible interference. If possible, run your wire antenna up a dedicated antenna tower. If you're installing your ham radio wire antenna using trees, make sure that the attachment point is solid, and that falling branches won't be able to knock down the antenna.
FCC Rules
The Federal Communications Commission is responsible for regulating amateur radio in the U.S. Part 97 of the regulations, which deals with ham radio, requires ham operators who install wire antennas higher than 200 feet, or who construct an antenna near an airport, to notify the FCC and the Federal Aviation Administration. Although air traffic control and ham radio operators use different radio frequency bands, these antennas could possibly cause interference with an aircraft's radio, and are therefore subject to FCC oversight.