As with most things in modern life, there is quite a lot of jargon associated with amateur radio. The list below explains some of the most common radio jargon.
Alternating Current. Current which changes direction, at a rate known as the "frequency". Also used as an adjective, as in AC voltage, AC circuit etc.
Same as ’antenna’. Widely used in the UK in relation to domestic radio and TV etc. (’Antenna’ is used for most engineering purposes.)
Audio Frequency. A frequency that can be heard by the human ear.
The unit of electric current. Abbreviated to Amp or A. (In formulae it is represented by I)
A device which increases something. It may apply to an audio frequency signal, or a radio radio frequency signal, or a current, or voltage etc.
Antenna Matching Unit. Same as ATU.
Amplitude Modulation. A method of modulation where the amplitude of the carrier is varied.
A radiator or collector of electromagnetic energy. Often called an aerial.
A device for reducing the level of RF or AF signals.
Antenna (or Aerial) Tuning Unit. Device to tune an antenna to resonance, and match it to the transmitter.
Balance-to-unbalance transformer. Often used to connect an unbalanced (coaxial) feeder to a balanced antenna, e.g. a dipole.
A range of adjacent radio frequencies.
Strictly this applies to a group of cells connected together. In general speech it is also used for single cells. When connected to a circuit a battery produces D.C.
Interference to broadcast radio reception.
A radio transmission concentrated to a greater or lesser extent in one direction rather than spreading uniformly in all directions.
Used (particularly by radio amateurs) to describe interference caused by the legitimate radiation from a transmitter entering a piece of equipment which has insufficient immunity.
The woven outer conductor of coaxial cables. The woven screen around screened cables. A woven (flat) conductor which gives a large conductor area.
A radio signal - or part of one - which is un-modulated.
A chemical device which produces an electric potential, and hence current. Often part of a battery
A choke impedes the passage of an alternating current b ut not direct current.
An arrangement of conductors and components in which an electric current moves
A type of feeder in which a central conductor is surrounded by an insulator, which is surrounded by another conductor. Used for carrying radio frequency signals to and from an antenna.
Often used by amateurs (particularly in the USA) as an abbreviation for Morse code.
Anything, solid liquid or gas, which allows electric current to flow through it. A good conductor has low resistance and vice versa.
An invitation to other stations to reply. Used to start an amateur radio contact.
A stream of electrons moving through a conductor. For historical reasons an electric current always flows from positive to negative. Measured in Amps.
Continuous Wave Morse sent by keying the carrier on and off. It is considerably more effective than voice when operating under difficult conditions, and for low power operation.
One cycle corresponds to one complete forward and reverse movement of an alternating current.
A generic term for communication of data with computers rather voice or Morse Code.
Abbreviation for decibel. A convenient way of expressing powers, voltages etc. as a logarithmic ratio.
Direct Current. Current which always flows in the same direction. Also used as an adjective as in DC voltage, DC circuit etc.
A device to extract the information a radio frequency signal carries.
A generic term for transmission of voice having been converted to data (digital) and its conversion back to analogue on reception. The various Digital Voice protocols (D-STAR, Fusion/C4FM, DMR) are totally incompatible with each other.
A resistor used in the place of an antenna to enable a transmitter to be tested or adjusted without radiating a signal.
A conductor buried in the ground. Assumed to be at zero potential for radio frequencies.
The protective conductor (at nominal earth potential).
Electromagnetic Compatibility. The ability of electronic devices and systems to operate without mutual interference.
Electromagnetic Interference.
Effective Radiated Power. The power radiated in the direction of maximum radiation. The power supplied to the antenna multiplied by the gain of the antenna.
A transmission line used to transfer the power from a transmitter or ATU to the antenna. Usually a coaxial cable or open-wire line.
Magnetic material which is used to increase the inductance of an inductor/coil. It can be made with a wide range of properties to suit different frequencies and applications. Usually it has a high electrical resistance. A "Ferrite Rod" is often used as part of the antenna in medium and long wave receivers.
A choke made by winding a lead on to a ring-shaped ferrite core.
A ferrite ring choke made by winding co-axial cable on to a ferrite ring. Used in TV down leads and similar applications. It can be viewed as impeding unwanted signals picked-up on the braid of the co-ax while leaving the wanted signals (inside the coax) unaffected.
A circuit which allows some frequencies to pass with a small loss, while attenuating other frequencies. Filters are often made up from several tuned circuits.
Frequency Modulation. A form of modulation in which the frequency is varied.
The number of cycles of an alternating current or voltage per second, which is also the number of complete waves of a radio signal passing a point in one second. Measured in Hertz.
A weak-signal datamode with prescribed message formats, using 15-second transmit/receive periods.
Same as earth.
Horizontal wires or metal surface spreading from a central common connection. Electrically they resemble a conducting ground surface.
An antenna consisting of a quarter wavelength vertical wire and a ground plane.
Radio waves which stay quite close to the ground. At high frequencies they do not get very far (a few km only).
Unwanted signals which are at an integer multiple of the transmitter carrier frequency.
The unit of frequency. One Hertz is one cycle per second.
High Frequency. The range of frequencies between 3.0MHz and 30MHz
The ability of a piece equipment to operate satisfactorily in the presence of a strong RF field.
1 A material which does not conduct electricity.
2 A fitting or covering made with an insulating material to prevent unwanted currents flowing to or from a conductor.
Radio signals difficult to separate from the one that interests you.
The layers of the upper atmosphere in which atoms are converted, mostly by ultraviolet light, to pairs of ions and electrons.
A hand operated switch which starts and stops the transmission of Morse to produce dots (“Dits”) and dashes (“Dahs”).
1 A circuit or conductor is said to be live when it has power connected to it.
2 The live wire of a mains supply (coloured brown) is the one at higher potential to earth.
The domestic electricity supply.
Radio signals with a wavelength (λ) less than 30cm and a frequency above 1000MHz.
A device which adds (or imposes) comparatively low frequency information to previously unchanging H.F.
Because the electric charge carried by an electron is deemed negative, an excess of electrons at a point is a negative charge.
The negative connection of a cell or power supply provides electrons at the same rate the positive accepts them.
1 Having neither excess nor shortage of electrons, ie no charge.
2 The blue neutral wire in a mains supply is the one closer to earth potential.
A background of naturally occurring random radio signals and/or signals produced by electrical machinery and electronic equipment.
The unit of resistance symbol Ω, named after a German scientist.
Antenna feeder consisting of two wires held at a constant separation by insulating spacers.
The regular changing of direction of alternating current and/or polarity of an AC voltage. It may be rapid (high frequency) or slow (low frequency).
A device which causes electrical oscillation. Most commonly it converts part of a direct current to alternating.
Two or more components operating 'side by side' with the corresponding connections of each linked together
Protective Multiple Earthing. An earthing arrangement used in some parts of the UK electricity distribution system.
Note that there is a potential safety issue associated with PME practice and amateur radio. The RSGB EMC Committee (web site) should be consulted for more information.
The direction of the electric field. Usually linear (e.g. horizontal or vertical).
Applies to the positive and negative of a cell or power supply, or the north and south poles of a magnet.
A positive electric charge is a lack of electrons at a point.
In a cell or power supply it is the connection which withdraws electrons from the circuit. (An equal number being released at the negative)
Equivalent to voltage, may be seen as the 'pressure' making electrical charges move. Used on its own it usually refers to the potential to the Earth.
The potential between two specified points.
The rate of doing work, transferring energy from one place to another, or changing it from one form to another. Measured in Watts.
Create radio waves. Normally from an antenna, where AC current in the feeder is transformed into radio waves.
Refers to the route taken by radio waves after leaving the antenna.
Phase Shift Keying. A form of data modulation which the phase of the carrier is varied. Similar to frequency shift keying.
A form of data transmission developed for amateur communications using a home computer in conjunction with an amateur transceiver. Like CW (Morse) it is very effective in difficult conditions and for low power operation.
Push (or Press) To Talk. The circuit which switches the transmitter from receive to transmit and vice versa.
International abbreviations originally defined for the maritime service to facilitate communications in Morse code. All are three letters starting with Q. Amateurs have adapted some Q codes for informal use. e.g. QSY (change frequency), QRT (stop transmitting), QRU (I have run out of things to talk about) etc.
A card with written confirmation of a radio contact.
A horizontal or sloping wire forming part of a ground plane antenna, spreading from a central point.
Refers to the creation of radio waves or their strength. It has nothing whatever to do with radioactivity.
A diagram indicating the directions in which radiation is stronger or weaker .
Equipment to separate, amplify and extract information from the minute signals collected by an antenna.
The opposition to an electric current given by any conductor. Measured in ohms (Ω). It may be great or small depending on the material and its shape and size.
A component designed to have a specific amount of resistance.
Radio Frequency
Radio Frequency Interference.
A datamode based on old teleprinter protocols. These days uses computers instead of teleprinters.
Conductive enclosure or partition. Sometimes used instead of ’braid’ to describe a woven outer conductor of a coaxial cable.
So far as amateurs are concerned, it is the service which does not have ’right of way’. On a shared band, where the Amateur Service is a secondary user, amateurs must take care not to cause interference to the primary user.
Two or more components connect 'one after the other' so that current flows through one and then the next.
A room/shed/etc. where an amateur radio station is set up.
Radio waves going upward; their direction may be changed in the ionosphere so that they return to earth a long way off.
Receivers that convert part of the radio spectrum to data and process the data to resolved the desired signal. Maybe part of a transceiver or may use a separate computer to do the processing.
Refers to the huge range of radio waves in the same way it refers to light. It can be applied to the entire range of electromagnetic waves.
Spurious emissions relatively close to the nominal carrier frequency. Can be caused by
overdriving an SSB transmitter.
Unwanted radiation that is outside the normal bandwidth of the transmission. It can include harmonics and other signals or noise.
Single Side Band. A power and spectrum efficient form of amplitude modulation in which only the minimum necessary part of the signal is transmitted. It is widely used for speech communications.
Standing Wave Ratio. An indication of the forward and reflected power in transmission lines, particularly antenna feeders.
Terminal Node Controller. A type of modem used in Packet radio which modulates the data onto audio tones which can be connected to the audio input of a transmitter and decodes the audio tones from a receiver and converts them back into data.
A combined transmitter and receiver.
Equipment for producing information carrying radio frequencies for supplying to an antenna via feeder.
A combination of an inductor and a capacitor which stores energy at one particular frequency - the Resonant frequency. It can be used to select a signal on one frequency and reject signals on other frequencies. Its behaviour is analogous to a bell or a tuning fork.
Adjusting the receiver to select the wanted signal.
Ultra High Frequency. The range of radio frequencies between 300MHz and 3000MHz.
Interference to TV reception.
Very High Frequency. The range of radio frequencies between 30MHz and 300MHz including the 6m (50MHz), 4m (70MHz) and 2m (144 MHz) amateur bands.
The unit of potential or voltage.
The electrical 'pressure' tending to make electrons move. Measured in Volts.
Radio waves are part of the wide range of electromagnetic waves, which are a self-sustaining combination of alternating electric and magnetic fields and travelling at the speed of light. Sound waves are pressure waves moving through air quite slowly.
The shape of one complete wave.
The distance between the crests (or any other corresponding points) of successive waves measured in metres. The distance occupied by one complete waveform. More easily visualised with water waves.
A type of antenna, consisting of a dipole accompanied by a reflector element and director elements. The usual type of television aerial. Capable of concentrating the transmission into a broad or narrow beam, according to design.