DIY CB Antennaby Joe Murray
Making your own CB mobile antenna requires a basic understanding of the frequency used by CB send and receive radios. The wavelength of the 27-MHz CB band is a little over 17 feet, or 204 inches; to send and receive CB, use two halves of this standing wavelength, or two 102-inch lengths of copper wire. Insulate and ground these two lengths of wire, connect them to your CB radio, and then mount them to the highest convenient point on your vehicle.
For the body of the antenna, use a 55- to 58-inch-long rod of any non-conductive material. It should be sturdy enough to stand up to a stiff breeze. A solid quarter-inch fiber glass shaft is ideal; aluminum, PVC or even wood will also work. For transmission, use two lengths of thin copper wire that are 110 inches long; the eight extra inches are for attachment. Use two small insulation eggs to isolate either end of the copper wire, or use duct tape to wrap the finished antenna. Use a length of RG-8 coaxial cable long enough to stretch from the spot where you'll mount the finished antenna to the location of your CB radio. Attach the proper connector -- generally an RP-SMA-Female -- to the other end after pulling the cable to the CB radio.
Having a quality soldering iron is important, as is a soldering stand to hold the antenna components while you're soldering. You need a roll of electronic solder, duct tape, as well as a roll of double-sided tape to hold the copper wire in place while wrapping it around the antenna rod. A standard toolset -- including screwdrivers, pliers and assorted clamps -- can also come in handy.
Wrap four inches of each end of the 110-inch copper wires through each end of the two insulator eggs, and then twist the wires to make a strong mechanical contact. Solder each twist to make a strong electrical contact. Loop the double-sided tape around the shaft of the antenna rod from top to bottom. A second set of hands is very helpful in this and the following tasks. Starting at one end of the antenna rod, wrap the copper wires around the shaft, keeping the two wires from touching each other. Cover the rod in duct tape either lengthwise or with a spiral wrap, making certain all parts of the rod are covered. Strip one end of the RG-8 cable, and then solder the center lead to one side of the insulator egg and the braided silver ground wire to the other. Cover the upper end of the rod with duct tape, leaving about four to five inches available for the mounting hardware.
Ideally, mount the antenna at the highest point on your vehicle. If this is inconvenient, any metallic surface will do. If you use a magnetic mount, run a ground wire from the braided silver wire of the RG-8 cable to any part of the vehicle chassis. A wide variety of antenna mounts is available online or at your local electronics retailer.