The 20-meter or 14 megahertz (MHz) radio band falls within the high-frequency amateur radio spectrum. Twenty meters designates the length of the particular radio wave used to transmit and receive voice and Morse code. Radioteletype is used frequently on this band as well. A dipole design for the 20-meter band is an efficient and inexpensive antenna for the novice and veteran ham enthusiast alike.
Separate the speaker wire into two 18-foot lengths. Measure 206 11/16 inches from the end of each wire, and cut the wires to this length. Strip 1/2 inch of insulation from both ends of each wire. These will be the dipole antenna elements.
Cut the connector from one end of the coaxial cable. Remove 1 inch of insulation from this end. Slice down the side of the braided sheath and twist the braid into a wire. Strip 1/2 inch of plastic insulation from the inner copper wire.
Orient the terminal strip so that the rows are vertical. Connect an antenna wire to each of the top screws. Attach the twisted braid wire and the coaxial copper wire to a separate bottom screw.
Crimp a ring terminal to the free end of each antenna wire.
Stretch the antenna wires out, forming a T shape. Hang the antenna taut using fishing line tied to the ring terminals.
Connect the free end of the coaxial cable to the external jack of the radio receiver.
Things You'll Need
- Speaker wire, 18-gauge, 18 feet long
- Coaxial cable, 75-ohm with connectors, 10 feet long
- Terminal strip, 2-position, dual-row
- Wire-stripping tool
- Utility knife
- Tape measure
- 2 ring terminal lugs
- Fishing line
For optimum performance, balance the antenna using an antenna tuner, or installing a 75- to 50-ohm balun between the free end of the coaxial cable and the radio receiver.
Adam Quinn has been writing since 2008. His articles have appeared in the "Journal of Humanistic Psychology." Quinn holds a Master of Social Work from the University of Washington in Seattle, where his focus of study was counseling combat veterans with post-traumatic stress disorder.