How the Single Sideband Radio Works

[Sue & Larry]

The single sideband radio is a lot like the HAM radio in the principle of operation. The major distinction is that it uses frequencies that are designated for marine operation only. Also, the SSB radio, without as many knobs and dials, is considerably easier to operate—and you don't have to pass a test to use it. Some SSB radios are also capable of transmitting and receiving on HAM frequencies, but you can't legally transmit unless you are a licensed HAM operator. A properly installed SSB radio has several components. In addition to the radio itself, there is an antenna, antenna tuner (or coupler), and ground plane. The most common antenna on sailboats is an insulated backstay. This is a section of backstay—23-foot or longer—that is fitted with insulators at the top and bottom. The insulated section is connected to the antenna coupler (usually mounted below decks) and serves as the antenna. From a distance it's barely detectable. Since it must transmit and receive on different frequencies, an automatic antenna coupler is needed. This is basically a little computer in a box that compensates for the fact that you can't change the length of the antenna with the change of frequency. (Remember high-school science: Different-length radio waves like certain-length antennas.) The coupler, which is mounted below the antenna and connects to the radio, matches the signal to the antenna so that the two work together efficiently. Lastly, and most importantly, for the signal to radiate from the antenna, it has to have a good ground plane. A ground consists of copper straps that tie the metal inside the boat together. The straps run back to the coupler and sometimes to the radio itself. The engine, fuel tanks, water tanks, keelbolts, through-hull fittings, and even the stern rail, are tied together with the copper straps to create a ground plane. Sometimes this is copper foil that is run from stern to bow under bunks next to the hull and tied back into the coupler. The goal is to create between 40 to 100 square feet of ground plane beneath the antenna. When the signal radiates from the antenna, it travels up to the ionosphere and bounces or skips back to earth (like a short-wave radio signal). This skip effect is what makes long-range communication possible. Different frequencies tend to reflect at different angles. Lower frequencies, like 4 MHz, reflect closer and higher frequencies, like 12 MHz, reflect farther away. The reflection angle changes according to the time of day or night, the season and the 11-year solar cycle. A diagram of radiating single sideband radio waves. It takes a little practice to learn which frequencies to use at a given time of day for the distance you wish to communicate. It's not difficult but there's definitely a learning curve. Just remember: There's always a friendly sailor out there who will be more than willing to share experiences or lend a helping hand.