Amateur Radio Foundation Glossary

Here’s a short summary of some of the terms that you may experience when studying towards your amateur radio Foundation exam:

Term Description
AM Amplitude Modulation. This is a method of combining audio (e.g. speech) with a carrier to create  radio signal. The audio changes the amplitude (height) of the carrier’s waveform
Balun A device that couples balanced and unbalanced feeder / antennas. For example, you would use a balan to connect a balanced antenna (such as a dipole), to unbalanced feeder (such as co-ax cable)
BNC Type of connector used for connecting between radio equipment and an antenna (bayonet connector, twist-and-click)
CQ A general call asking for someone to make contact with you. Derives from “I Seek You”. As part of the Foundation practicals, you’ll have to make a CQ call. See our VHF QSO Video
CW Continuous Wave – Also known as Morse Code
CTCSS Continuous Tone Coded Squelch System. Sub-audible tone by your radio sent alongside a transmission, to allow a repeater to “open”. The helps to ensure that the repeater will only forward genuine messages
Dummy Load Device that plugs into a transmitter’s antenna socket to allow you to test a transmitter without radiating a signal into an antenna
EMC Electro-Magnetic Compatibility. A device’s immunity to interference. EMC issues relate to electrical or radio interference to other equipment.
ERP Effective Radiated Power  – How much power your antenna is outputting (calculated by multiplying the power in watts, by the “gain” of the antenna)
FM Frequency Modulation. Method of combining a radio signal with a carrier. The signal changes the frequency of the carrier’s waveform
Ionosphere Layer of conductive gases 70-400km above Earth, that refracts radio signals back to Earth – Used to make HF contacts beyond line-of-sight
Ohm’s Law The Voltage equals the Current multiplied by the Resistance (V = I x R)
PL-259 Type of connector used for connecting between radio equipment and an antenna (screw-thread)
Q Codes Shorthand codes used on amateur radio dating back to early Morse Code days. Common codes are: QTH (Location) ; QSL (Acknowledgement of receipt) ; QRZ (Who is calling) ; QRM (Man-made interference) ; QRP (Reduced power) ; QSY (Change frequency) ; QSO (communication / contact). Can be a question or a statement- e.g. “QSL?”… “QSL” (Did you get that? Yes, I got that)
RF Radio Frequency
SSB Single Sideband. The exact definition is outside the scope of Foundation, but there are two types: USB (Upper Sideband) and LSB (Lower Sideband). These are methods of transmission, like FM and AM
VSWR Voltage Standing Wave Ratio. Often shortened to SWR.  An SWR of 1:1 would indicate that all of the power from the transmitter is being radiated by the antenna. An SWR reading of 2:1 or higher would indicate that a significant amount of power is reflected back to the transmitter from the antenna (indicating an antenna mismatch). One of the Foundation practicals involves adjusting the VSWR of a dipole. See Station Build Practical Video
TNC Terminal Node Controller. Type of interface between a computer and a radio – used for data modes over amateur radio.
Yagi A beam antenna. Typically has a gain, and focusses energy into a single beam


Anything you’d like us to add, or that’s not clear? Let us know!



  1. Christopher fancett 22nd September 2016 Reply
    • petes 23rd September 2016 Reply
  2. peter gray 3rd March 2017 Reply

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