Amateur radio explained
No formulas here. This is the mental model that makes everything else on the site - and most of the exam - make sense.
What a radio wave is
When you push electric current back and forth along a wire very fast, some of that energy leaves the wire and travels away as a wave. Another wire, far away, catches a tiny amount of it and turns it back into a current a receiver can hear. That is all a radio contact is: one wire shaking, and another wire noticing.
Frequency, wavelength and bands
Frequency is how many times a second the wave shakes, measured in hertz. Millions of times a second is megahertz (MHz). Wavelength is the physical distance between wave peaks - and the two are just two ways of saying the same thing: higher frequency means shorter wavelength. That is why hams say "the 2 metre band" and "the 20 metre band"; those names are the size of the wave, and they tell you roughly how big your antenna needs to be.
A band is a slice of frequencies set aside for a purpose. Amateurs get a couple of dozen slices, and they behave very differently:
| Group | Example bands | Behaves like | Good for |
|---|---|---|---|
| HF (shortwave) | 80m, 40m, 20m | Bounces off the upper atmosphere | Other states and other continents |
| VHF | 6m, 2m | Mostly line of sight, a bit further | Local contacts, repeaters, satellites |
| UHF | 70cm | Line of sight, gets into buildings well | Around town, handhelds, data |
| Microwave | 23cm and up | Very line of sight | Experimenting, high-speed data, video |
Why signals go further at night
High above you, sunlight knocks electrons loose in the thin upper atmosphere, creating a layer called the ionosphere. Shortwave signals hitting it at a shallow angle get bent back to earth hundreds or thousands of miles away - like skimming a stone off the underside of a ceiling. As the layers shift between day and night, and with the eleven-year solar cycle, different bands open and close. That is why an operator can talk to Japan one evening and hear nothing at all on the same band the next morning. Chasing those conditions is half the fun.
Watts, decibels and why more power is not the answer
Doubling your transmit power makes barely a perceptible difference at the far end. Raising your antenna, or using a better one, usually makes a large one. This is the single most useful thing a beginner can know, and it is why experienced operators talk endlessly about antennas and hardly ever about amplifiers.
Modes: the ways of putting information on a wave
- FM - clean and easy, short range. What repeaters and handhelds use.
- SSB - efficient voice mode used on shortwave for long distances. Sounds odd until you tune it in correctly.
- CW (Morse) - the narrowest and toughest signal of all; gets through when nothing else will.
- Digital - the computer does the talking, and can decode signals far too weak for your ears. More on this.
The jargon, decoded
| You will hear | It means |
|---|---|
| Rig | The radio itself |
| Shack | Wherever your station lives, even if it is a shelf |
| QTH | Location |
| QSO | A contact or conversation |
| QSL | Confirming a contact, often with a postcard |
| 73 | Best wishes, said at the end of a contact |
| Elmer | An experienced operator who mentors a new one |
| DX | A distant station |
Want the full technical treatment - bands and privileges, propagation, feedlines, matching, and the maths this page skips? That is what the wiki is for.