By Dan Romanchik, KB6NU
By Dan Romanchik, KB6NU
One of the most frequent questions that newcomers to amateur radio ask is, “How far can you talk on ham radio? One answer is “all around the world.” An equally common, but equally vague, answer is, “It depends.”
Both answers are correct, but perhaps an even better answer is a combination of the two. What I’d say is, “You can talk all around the world on ham radio, but it depends.” The distance a signal will reach depends on a lot of things, including:
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Arguably, the biggest factor that determines how far you can talk on the radio is the frequency you’re operating on. Here’s a chart that shows the radio spectrum and all the different frequency bands that are available to amateur radio operators:
Amateur radio operators can transmit on frequencies as low as 136 kHz and as high as 250 GHz. Since most newcomers buy radios that operate in the VHF and UHF regions, let’s look at those bands first.
We use VHF, UHF, and microwave frequencies mostly for line-of-sight terrestrial communications. How far you can talk using line-of-sight communications depends on how much power your radio is capable of outputting, how high your antennas are, the terrain, and whether or not you’re communicating radio to radio (simplex operation) or using a repeater (duplex operation).
For example, if you and a friend are using handheld transceivers (HTs) with a typical output power of 5 watts, you can expect your range to be about 5 miles maximum. Of course, this depends on the terrain and other obstacles that might block transmissions, so in urban settings, your range will be much shorter.
For example, if you and a friend are using handheld transceivers (HTs) with a typical output power of 5 watts, you can expect your range to be about 5 miles maximum.
A repeater station located in the mountains, for example, may have a range of hundreds of miles
Skip distances can easily reach 3000 miles or more.
One of the keys to good skywave propagation is the condition of the ionosphere. The more energetic the ionosphere is, the better it will refract radio waves. This energy comes from the sun and increases and decreases over an 11-year cycle, sometimes called the sunspot cycle, At the peak of the sunspot cycle, worldwide communication on the HF bands is possible with low power and simple antennas. At the bottom of the cycle, long-distance communications it is still possible, but more difficult.
Skywaves with frequencies above 30 MHz tend to go right through the ionosphere and head off into space (with some exceptions, of course). This is actually a good thing. For example, we use frequencies in the VHF, UHF, and microwave portions of the spectrum to communicate with satellites and other spacecraft. It would be impossible to communicate with the International Space Station (ISS) if all radio waves were reflected by the ionosphere.
Note that there are many exceptions to what I’ve described above. There is, for example, a propagation mode called “sporadic E” allows long-distance communications on 6-meter and 2-meter frequencies, frequencies that are normally restricted to line-of-sight communications. Learning about these modes and figuring out how to use them is part of the fun of being a radio amateur.
