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 balun 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)
PME This standas for Protective Multiple Earthing, and relates to one of the ways that electricity companies connect houses to Earth. Special care is needed with RF earthing arrangements if your house has PME. More details can be found in the RSGB’s guide: RSGB UK Earthing Systems and RF Earthing
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!

Handy Links


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

Add a Comment

Your email address will not be published. Required fields are marked *