{"id":14295,"date":"2016-07-17T16:20:58","date_gmt":"2016-07-17T15:20:58","guid":{"rendered":"http:\/\/www.essexham.co.uk\/?page_id=14295"},"modified":"2024-06-16T22:08:07","modified_gmt":"2024-06-16T21:08:07","slug":"glossary","status":"publish","type":"page","link":"https:\/\/www.essexham.co.uk\/train\/glossary\/","title":{"rendered":"Amateur Radio Foundation Glossary"},"content":{"rendered":"

Here’s a short summary of some of the terms that you may experience when studying towards your amateur radio Foundation exam:<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Term<\/strong><\/td>\nDescription<\/strong><\/td>\n<\/tr>\n
AM<\/strong><\/td>\nAmplitude Modulation. This is a method of combining audio (e.g. speech) with a carrier to create a radio signal. The audio changes the amplitude (height) of the carrier\u2019s waveform<\/td>\n<\/tr>\n
AMU<\/strong><\/td>\nAntenna Matching Unit. Used to \u201cmatch\u201d antenna impedance to the transmitter, to reduce VSWR<\/td>\n<\/tr>\n
Attenuate<\/strong><\/td>\nTo reduce the energy of a radio signal. As an example, heavy rain attenuates (reduces the strength of) radio signals at UHF and above<\/td>\n<\/tr>\n
Balun<\/strong><\/td>\nA 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 coax cable<\/td>\n<\/tr>\n
BNC<\/strong><\/td>\nType of connector used for connecting between radio equipment and an antenna (bayonet connector, twist-and-click)<\/td>\n<\/tr>\n
CQ<\/strong><\/td>\nA general call asking for someone to make contact with you. Derives from \u201cI Seek You\u201d.<\/td>\n<\/tr>\n
CW<\/strong><\/td>\nContinuous Wave \u2013 Also known as Morse Code<\/td>\n<\/tr>\n
CTCSS<\/strong><\/td>\nContinuous Tone Coded Squelch System. Sub-audible tone sent by your radio alongside a transmission to allow a repeater to \u201copen\u201d. This helps to ensure that the repeater will only forward genuine messages<\/td>\n<\/tr>\n
dB (Decibels)<\/strong><\/td>\nUnit associated with the measurement of gain (or loss). At Foundation, recall that Yagi (beam) antennas have a gain measured in dB, for example, a Yagi with a 3dB gain would double the radiated power<\/td>\n<\/tr>\n
Dummy Load<\/strong><\/td>\nA device that plugs into a transmitter\u2019s antenna socket to allow you to test a transmitter without radiating a signal into an antenna<\/td>\n<\/tr>\n
EMC<\/strong><\/td>\nElectro-Magnetic Compatibility. The avoidance of interference between various pieces of electronic equipment.<\/td>\n<\/tr>\n
EMF<\/strong><\/td>\nElectro-Magnetic Fields. Antennas generate EMF when transmitting and amateurs are required to ensure that EMF they generate is below recommended international limits.<\/td>\n<\/tr>\n
EIRP<\/strong><\/td>\nEffective Isotropic Radiated Power \u2013 How much power is being radiated by your antenna (compared to a theoretical “isotropic” antenna)<\/td>\n<\/tr>\n
ERP<\/strong><\/td>\nEffective Radiated Power \u2013 How much power your antenna is outputting (calculated by multiplying the power in watts, by the \u201cgain\u201d of the antenna when compared to a half-wave dipole antenna)<\/td>\n<\/tr>\n
FM<\/strong><\/td>\nFrequency Modulation. Method of combining a radio signal with a carrier. The signal changes the frequency of the carrier\u2019s waveform<\/td>\n<\/tr>\n
Impedance<\/strong><\/td>\nAn antenna has an impedance, which is measured in Ohms at the feed point. The impedance depends on the size, shape of the antenna, how it’s positioned, and the frequency transmitted. You would use an AMU (Antenna Matching Unit) to match the impedance of the antenna and feeder, with the transmitter, to ensure that the system is as efficient as possible.<\/td>\n<\/tr>\n
Ionosphere<\/strong><\/td>\nLayer of conductive gases 70-400km above Earth, that refracts radio signals back to Earth \u2013 Used to make HF contacts beyond line-of-sight<\/td>\n<\/tr>\n
Ohm\u2019s Law<\/strong><\/td>\nThe Voltage equals the Current multiplied by the Resistance (V = I x R). Need help? Ohm’s Law Triangle Explained<\/a><\/td>\n<\/tr>\n
PL-259<\/strong><\/td>\nType of connector used for connecting between radio equipment and an antenna (screw-thread)<\/td>\n<\/tr>\n
PME<\/strong><\/td>\nThis stands 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<\/a><\/td>\n<\/tr>\n
Q Codes<\/strong><\/td>\nShorthand 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). They can be a question or a statement- e.g. \u201cQSL?\u201d\u2026 \u201cQSL\u201d (Did you get that? Yes, I got that)<\/em><\/td>\n<\/tr>\n
RF<\/strong><\/td>\nRadio Frequency<\/td>\n<\/tr>\n
SSB<\/strong><\/td>\nSingle Sideband. There are two types: USB (Upper Sideband) and LSB (Lower Sideband). These are methods of transmission, like FM and AM<\/td>\n<\/tr>\n
VSWR<\/strong><\/td>\nVoltage Standing Wave Ratio. Often shortened to SWR. \u00a0An 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).<\/td>\n<\/tr>\n
Yagi<\/strong><\/td>\nA beam antenna. Typically has a gain (measured in dB), and focuses energy in a single direction<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

This list can be downloaded as a PDF – See www.essexham.co.uk\/getstarted<\/a><\/p>\n

Anything you’d like us to add, or that’s not clear? Let us know!<\/p>\n

Handy Links<\/h3>\n