GB/T 26667-2021Terminology for electromagnetic shielding materials (English PDF)

3.1 Electromagnetic field

3.1.1 Electromagnetic(EM)wave

The radiant energy produced by the oscillation of the electric charge is characterized by the oscillation of the electromagnetic field. [Source: GB/T 17626.3-2016, 3.6]

3.1.2 Electromagnetic radiation

A phenomenon in which energy is emitted from a source to space in the form of electromagnetic waves, or a state in which energy is propagated in space in the form of electromagnetic waves.

Note: The meaning of the term "electromagnetic radiation" can sometimes be extended to include the phenomenon of electromagnetic induction. [Source: GB/T 4365-2003, 161-01-10, with modification]

3.1.3 Electric field strength

The ratio of the force F acting on a static charged particle to the particle charge Q. Where. E --- Electric field strength, in volts per meter (V/m);

F --- the force acting on a static charged particle, the unit is Newton (N);

Q --- The charge of a charged particle, the unit is coulomb (C). [Source: GB/T 2900.60-2002, 121.11.18, with modification]

3.1.4 Magnetic fieldstrength

The magnitude of the force of the magnetic field on the electric charges moving in the field.

Note: The magnetic field strength is a basic quantity that characterizes the characteristics of the magnetic field, it is a vector, and the unit is ampere per meter (A/m). [Source: JJF1188-2008, 12.2, with modification]

3.1.5 Powerfluxdensity

The energy passing along the normal direction of the unit area per unit time.

Note: The power flux density is a scalar, which is the time average of Boynting's vector mode, in watts per square meter (W/m2). [Source: JJF1188-2008, 12.4, with modification]

3.1.6 Electromagnetic shielding

Use conductive, magnetic, or conductive and magnetic materials to reduce or block the propagation of the electromagnetic field to the designated area.

3.1.7 Shieldingeffectiveness

At a certain point under the same excitation, the ratio of the electric field strength, magnetic field strength or power measured with shielding material and without shielding material. SE=20lg(E2/E1) Or SE=20lg(H2/H1) Or SE=10lg(P2/P1) Where. SE ---shielding effectiveness, in decibels (dB);

H1---Magnetic field strength without shielding material, in ampere per meter (A/m);

H2---Magnetic field strength with shielding material, the unit is ampere per meter (A/m);

E1 --- Electric field strength without shielding material, in volts per meter (V/m);

E2 --- the electric field strength when there is shielding material, the unit is volts per meter (V/m);

P1 --- the power when there is no shielding material, in watts (W);

P2 --- The power when there is shielding material, the unit is watts (W).

Note: The shielding effectiveness is usually a negative value, but it is customary to use its absolute value.

3.1.8 Surface resistivity

The ratio of the direct current electric field intensity on the surface layer of the material to the linear current density is the surface resistance per unit area.

Note: The unit of surface resistivity is expressed in ohms (ohm).

3.1.9 Volume resistivity

The ratio of the intensity of the DC electric field in the material body to the steady-state current density is the volume resistance per unit volume.

Note: The unit of volume resistivity is expressed in ohm meters (ohm·m).

3.1.10 Electromagnetic thermal effect

After the electromagnetic energy entering the organism is converted into heat energy, it can increase the local or overall temperature, resulting in changes in its tissue structure or physiological or physical changes. Biological effects of changes in biochemical indicators.

3.1.11 Bio-electromagneticathermaleffect

After organisms absorb electromagnetic energy, the biological effects produced are not attributable to temperature changes.

3.1.12 Nearfield

< Measurement> A field that satisfies r>2D2/lambda electromagnetic field division conditions. Where. r --- field source distance, in meters (m);

D --- the effective aperture of the transmitting antenna, in meters (m); lambda ---The wavelength of electromagnetic waves, in meters (m).

Note 1.In the near field, the reactance of the electrically small antenna satisfies D/lambda< 1.

Note 2.The near field is dominated by the induction field. [Source: JJF1188-2008, 12.5, with modification]

3.1.13 Farfield

< Measurement> A field that satisfies r>2D2/lambda electromagnetic field division conditions. Where. r --- field source distance, in meters (m);

D --- the effective aperture of the transmitting antenna, in meters (m); lambda ---The wavelength of electromagnetic waves, in meters (m).

Note 1.In the far field, for an electrically large antenna, r takes the maximum of 10D and 2D2/lambda; the radiation of an electrically small antenna satisfies r >lambda/2pi.

Note 2.The far field is dominated by the radiation field. [Source: JJF1188-2008, 12.6, with modification]

3.1.14 Reflection attenuation

The ratio of reflected power to incident power after electromagnetic waves are irradiated on the surface of the material. Where. Ra-reflection attenuation, in decibels (dB); Pr---Reflected power, in watts (W); Pi-Incident power, in watts (W). [Source: GB/T 32596-2016, 3.2, with modification]

3.1.15 Transmissionattenuation

After the electromagnetic wave irradiates the surface of the material, the ratio of transmitted power to incident power. Where. Ta---transmission attenuation, in decibels (dB); Pt---transmitted power, in watts (W); Pi --- incident power, in watts (W). [Source: GB/T 32596-2016, 3.3, with modification].

3.1.16 Power loss

The ratio of the power absorbed by the material to the incident power after the electromagnetic wave is irradiated on the surface of the material. Pi-Pt-Pr Where. PL --- power loss, in watts (W); Pi --- incident power, in watts (W); Pt ---transmitted power, in watts (W); Pr ---Reflected power, in watts (W). [Source: GB/T 32596-2016, 3.4, with modification]

3.2 Electromagnetic shielding materials

3.2.1 Electro-conductive fiber

A general term for fibers made of conductive materials all or on the surface.

3.2.2 Metalfiber

Fiber made of metal.

Note: Such as stainless steel fiber, nickel fiber, iron fiber, copper fiber and silver fiber.

3.2.3 Metalized fiber

Using physical or chemical methods, a conductive fiber with a metal layer is formed on the surface of the fiber.

Note: Such as silver-plated fiber, copper-plated fiber, nickel-plated fiber, etc.

3.2.4 Carbonfiber

Inorganic fiber composed of carbon element.

Note: Carbon fiber can generally be divided into ordinary carbon fiber, high-strength carbon fiber, high-modulus carbon fiber, etc. according to product performance.

3.2.5 Modified electro-conductive fiber

The fiber is modified by blending, chemical grafting, chelating (such as ionic conductive fiber) and other methods to make it a conductive fiber.

3.2.6 Electro-conductive yarn

It is made of conductive fiber purely spun or blended with other fibers, and it is conductive directly on the surface of the yarn after conductive treatment Capable yarn.

3.2.7 Electromagnetic shielding fabric

Fabrics made of conductive and magnetically conductive functional fibers and yarns, or the fabrics are treated with surface metallization, coating, etc., to make them have Electromagnetic shielding effect

Note: Metallization treatment includes vacuum coating method, electroless plating, electroplating, etc.

3.2.8 Metalized electro-conductive fabric

Using various fiber fabrics as the base material, after surface treatment, the metal layer is deposited by physical or chemical methods to make it conductive, electromagnetic Soft conductive material with shielding function. [Source: GB/T 30139-2013, 3.1.1]

3.2.9 Electro-conductive yarnnet

Using various polymer material mesh fabrics as the base material, after surface treatment, the metal layer is deposited by physical or chemical methods to make it conductive. Soft conductive material with electrical and electromagnetic shielding function. [Source: GB/T 30139-2013, 3.1.2]

3.2.10 Electro-conductivenon-woven fabric

Using various non-woven fabrics as the base material, after surface treatment, the metal layer is deposited by physical or chemical methods to make it conductive and electromagnetic screen Soft conductive material with shielding function. [Source: GB/T 30139-2013, 3.1.3]

3.2.11 Electro-conductive fiber fabric

A fabric with electromagnetic shielding function made by blending or interweaving conductive fibers or yarns with other fibers or yarns. [Source: GB/T 30139-2013, 3.2]

3.2.12 Stainless steel fiber fabric

An electromagnetic shielding fabric containing stainless steel fibers. [Source: GB/T 30139-2013, 3.2.1, with modification]

3.2.13 Metalized fiber fabric

A fabric with electromagnetic shielding function containing metalized fibers (blend or pure spinning).

Note: Such as silver-plated fiber fabric, copper-plated fiber fabric, nickel-plated fiber fabric, etc.

3.2.14 Metalion-cyanchelated fiber fabric

One or more metal cations are applied to the cyano group of the fiber through chelation to make it a fabric with electromagnetic shielding function. [Source: GB/T 30139-2013, 3.2.3]

3.2.15 Electromagnetic shielding metal wire mesh

A mesh structure material made of metal with electromagnetic shielding function.

Note: Including mesh structure materials made by weaving, metallization, coating, etching and other methods.

3.2.16 Electro-conductivemetalwiremesh

Use various metal wire meshes as the substrate, and deposit other metal layers by physical or chemical methods on its own or after surface treatment, which has conductive Soft conductive material with electrical, electromagnetic shielding, oxidation resistance and other properties. [Source: GB/T 30139-2013, 3.1.4]

3.2.17 Electromagnetic shielding coating

It can be coated on the base material and has an electromagnetic shielding function.

3.2.18 Electromagnetic shielding tape

Adhesive and fixing tape for electromagnetic shielding purposes.

3.2.19 Electro-conductiveadhesive

Conductive adhesive Conductive adhesive Adhesive with certain conductivity and bonding effect for the purpose of conductive connection.

3.2.20 Electro-conductive gasket

A type of electromagnetic shielding material used at the joint and the joint surface to ensure effective conductive contact.

3.2.21 Finger Reed fingerstock

Flexible shielding material made of sheet metal.

3.2.22 Electro-conductive foam

The sponge with conductive function or the elastic body with electromagnetic shielding function formed by wrapping conductive material on the outer layer of the sponge.

3.2.23 Electromagnetic shielding hasp/zipper

Metalizing Velcro/Nylon zippers or resin zippers to make them conductive and used for electromagnetic shielding that requires frequent opening and closing The connection of the gap.

3.2.24 Electromagnetic shielding rubber

An electromagnetic shielding material that adds conductive or magnetic materials to the rubber matrix and maintains the characteristics of rubber.

3.2.25 Electromagneticshieldingplastic

The plastic resin and the conductive or magnetic material are mixed to make a polymer material with electromagnetic shielding function.

3.2.26 Electromagnetic shielding plate

A plate-shaped electromagnetic shielding material used to build an electromagnetic shielding shell and shield the electromagnetic field inside and outside the shell.

3.2.27 Transparent electromagnetic shielding material

It is a transparent material with electromagnetic shielding function for observation windows and display windows of electronic equipment.

3.2.28 Electromagnetic shielding glass

Light-transmitting device with electromagnetic shielding function based on glass.

3.2.29 Electromagnetic shielding film

It is a non-optical film with conductivity and electromagnetic shielding effect after metallization treatment with polymer film as the main substrate.

3.2.30 Waveguideventilatingboards

A ventilation plate that uses the cut-off characteristics of the waveguide to achieve electromagnetic shielding function.

3.2.31 Waveguidevent

The waveguide and the ventilation window are combined into a whole to form a device that not only allows air circulation, but also realizes electromagnetic shielding. [Source: GB 50174-2017, 2.1.18, with modification]

3.2.32 Intrinsicconductingpolymer

Polymers with conjugated pi bonds are chemically or electrochemically "doped" to convert them from an insulator to a conductive polymer material.

3.2.33 Eletro-conductive nanomaterial

At least one dimension of the material structure in the three-dimensional space is at the nanometer scale, or is composed of nanostructure units and has special properties. Electric materials.

3.2.34 Electromagnetic wave absorbing material

Absorbing material A material that can absorb electromagnetic energy.

3.2.35 Electromagnetic shielding shrinkable tube

With electromagnetic shielding function, under heating conditions, the shielding layer and the substrate shrink simultaneously in the radial direction, including the tubular composite of the shielding layer and the substrate material.

3.2.36 Magneticshieldingplate

A plate-shaped magnetic shielding material used to build a magnetic shielding shell and shield the magnetic field inside and outside the shell.

3.2.37 Electromagnetic shielding foil

A sheet with electromagnetic shielding function that is stretched out of metal.

A.1 Basic radio terms

A.1.1 Frequency The rate of repetition time or the number of repetitions of the event in 1s.

Note: The unit of frequency is hertz (tz), and the symbol is Hz. The frequency of electrical signals is usually measured in multiples of hertz (tz), such as kilohertz (1 kHz = 10^3 Hz), megahertz (1 MHz = 10^6 Hz), gigahertz (1 GHz = 10^9 Hz). [Source: JJF 1180-2007, 3.1, with modification]

A.1.2 Transverse electromagnetic wave TEM wave An electromagnetic wave in which the electric field component and the magnetic field component are perpendicular to each other, and both are perpendicular to the direction of propagation. [Source: JJF1188-2008, 1.12]

A.1.3 Plane electromagnetic wave Plane wave The wave front is a plane electromagnetic wave. [Source: JJF1188-2008, 1.13]

A.1.4 Incidentpower The power of the signal source incident on any load. [Source: JJF1188-2008, 5.5] A.1.5 Reflectedpower The power reflected by the load. [Source: JJF1188-2008,5.6]

A.1.6 Attenuation When a two-port network is inserted into a non-reflective system composed of a signal source and a load, the relative change of power on the load before and after insertion.

Note: The unit of attenuation is expressed in decibels (dB). [Source: JJF1188-2008, 8.1, with modification]

A.1.7 Standing wave ratio The ratio of the amplitude of the antinode of the standing wave to the amplitude of the node. [Source: GB/T 1417-1978, 1.12.14]

A.1.8 Electromagneticenvironment The sum of all electromagnetic phenomena that exist in a given place.

Note: Usually, the electromagnetic environment is related to time, and its description may require statistical methods. [Source: GB/T 4365-2003,161-01-01]

A.1.9 Electromagnetic disturbance Any electromagnetic phenomenon that may cause degradation of device, equipment, or system performance or adversely affect biological or non-living organisms.

Note: Electromagnetic disturbance may be caused by electromagnetic noise, unwanted signals or changes in the propagation medium itself. [Source: GB/T 4365-2003,161-01-05]

A.1.10 Electromagnetic interference;EMI The performance degradation of equipment, transmission channels or systems caused by electromagnetic disturbance indicates the consequences.

Note 1.The terms "electromagnetic disturbance" and "electromagnetic interference" mean "cause" and "consequence" respectively.

Note 2.In the past, "electromagnetic disturbance" and "electromagnetic interference" were often used together. [Source: GB/T 4365-2003,161-01-06]

A.1.11 Electromagnetic compatibility electromagnetic compatibility; EMC The equipment or system can work normally in its electromagnetic environment and does not constitute unbearable electromagnetic disturbance to anything in the environment ability. [Source: GB/T 4365-2003,161-01-07]

A.1.12 Characteristic impedance The ratio of the incident wave voltage to the incident wave current on the transmission line, or the negative value of the ratio of the reflected wave voltage to the reflected wave current. epsilonr Where. Z0---Characteristic impedance of the coaxial line, in ohms (ohm);

D ---The inner diameter of the outer conductor of the coaxial line, in meters (m); d ---The outer diameter of the inner conductor of the coaxial line, in meters (m);

epsilonr --- The relative permittivity of the filling medium between the inner and outer conductors.

Note 1.Common characteristic impedance of coaxial cable is 50ohm and 75ohm.

Note 2.The waveguide transmits dispersive waves, and the characteristic impedance has different values for the different wave types transmitted. [Source: JJF1188-2008, 6.2, with modification]

A.1.13 Reflection coefficient The ratio of the reflected wave amplitude to the incident wave voltage amplitude at any point on the microwave transmission line. [Source: JJF1188-2008, 6.4, with modification]