RFRSO Glossary
Based on: ARPANSA Standard for Limiting Exposure to Radiofrequency Fields—100kHz to 300GHz, Radio Protection Series S-1.
Absorbed energy density (Uab): For frequencies above 6 GHz, the RF energy absorbed per unit area within very superficial regions of the body, expressed as joule per square metre (J/m2).
Absorbed power density (Sab): For frequencies above 6 GHz, the RF power absorbed per unit area within very superficial regions of the body, expressed as watt per square metre (W/m2).
Basic restrictions: The mandatory limiting values of exposure expressed in terms of selected quantities that closely match all known biophysical interaction mechanisms that may lead to health effects.
Contact current: The resulting current produced by touching an electrically charged conductive surface or object within an electromagnetic field.
Electric current (I): Flow of electrical charge, expressed in ampere (A).
Electric field (E): Region around an electric charge in which an electric force is exerted on another charge. The strength of the electric field is expressed in units of volt per metre (V/m).
Electromagnetic field: A time and space varying field associated with electric and magnetic forces on electric charges as described by Maxwell’s equations. It can be characterized at any instant by electric (E) and magnetic (H) field vectors.
Exposure: That which occurs whenever a person is subject to the influence of an RF field or contact current.
Far-field: Region sufficiently far from the source that the phase and amplitude relationships of the waves arriving from different areas of the antenna do not change appreciably with distance. The antenna gain and angular pattern are essentially independent of distance, and the power density (in free-space paths) is inversely proportional to the square of the distance from the source.
Frequency: The number of sinusoidal cycles completed by electromagnetic waves in 1 second, expressed in hertz (Hz).
Incident electric field strength (Einc): Electric field incident on the body surface, expressed in volt per metre (V/m).
Incident energy density (Uinc): The amount of RF energy through a unit area incident on the body surface, expressed in joule per square metre (J/m2).
Incident magnetic field strength (Hinc): Magnetic field incident on the body surface, expressed in ampere per metre (A/m).
Incident power density (Sinc): The rate of RF energy through a unit area incident on the body surface, expressed in watt per square metre (W/m2).
Induced electric field (Eind): Electric field inside the body as a result of exposure to an external electromagnetic field, expressed in volt per metre (V/m).
Limb current: Current flowing through the limbs, such as through an ankle or wrist
Magnetic field (H): Region where a force is produced by electric currents. The strength of the magnetic field is expressed in ampere per metre (A/m).
Medical exposure: Exposure of a person to RF fields received as a patient undergoing medical diagnosis or recognised medical treatment, or as a volunteer in medical research. Medical exposure also applies to carers and comforters of patients.
Near-field: Region of an electromagnetic field that is between the transmitting source and the far field. It is subdivided into the reactive and radiating near field regions.
Over-exposure: Exposure exceeding the relevant local or whole-body basic restrictions taking into account the appropriate averaging time (e.g. 6 minutes or 30 minutes). A short-term exposure to a level exceeding the basic restriction typically does not lead to an over-exposure unless the time-averaged level is above the relevant limit.
Plane wave: An electromagnetic wave in which the electric and magnetic field vectors lie in a plane perpendicular to the direction of wave propagation.
Plane-wave equivalent incident power density (Seq): RF power per unit area, equal in magnitude to the power density of a plane wave having the same electric or magnetic field strength, expressed in watt per square metre (W/m2).
Plane-wave equivalent incident energy density (Ueq): RF energy per unit area, equal in magnitude to the energy density of a plane wave having the same electric or magnetic field strength, expressed in joule per square metre (J/m2).
Radiating near-field: The region between the reactive near field and the far field. Reactive components of the electric and magnetic fields are insignificant, and the relationships between the electric and magnetic fields are approximately the same as in the far field.
Radiofrequency (RF): Electromagnetic field with frequencies in the range 100 kHz to 300 GHz.
Reactive near-field: The region immediately surrounding an antenna or source where the non-radiating (reactive) components of the electric and magnetic fields are significant and essentially unrelated to each other.
Reference levels: Practical or ‘surrogate’ parameters that may be used for determining compliance with the basic restrictions.
RMS: The root mean square which is derived by first squaring a set of numbers and then determining the mean value of the squares obtained, and taking the square root of that mean value.
Specific energy absorption (SA): The RF energy absorbed per unit mass of biological tissue, expressed in joule per kilogram (J/kg).
Specific energy absorption rate (SAR): The rate at which RF energy is absorbed in body tissues, expressed in watt per kilogram (W/kg).
Unperturbed values: Electromagnetic field quantity values in the absence of the human body.
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