1、 IEC/IEEE 62704-1 Edition 1.0 2017-10 INTERNATIONAL STANDARD Determining the peak spatial-average specific absorption rate (SAR) in the human body from wireless communications devices, 30 MHz to 6 GHz Part 1: General requirements for using the finite-difference time-domain (FDTD) method for SAR calc
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12、ication or need further assistance, please contact the Customer Service Centre: csciec.ch. IEC/IEEE 62704-1 Edition 1.0 2017-10 INTERNATIONAL STANDARD Determining the peak spatial-average specific absorption rate (SAR) in the human body from wireless communications devices, 30 MHz to 6 GHz Part 1: G
13、eneral requirements for using the finite-difference time-domain (FDTD) method for SAR calculations INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 17.220.20; 33.060.20 ISBN 978-2-8322-4769-3 Warning! Make sure that you obtained this publication from an authorized distributor. Registered trademark of t
14、he International Electrotechnical Commission 2 IEC/IEEE 62704-1:2017 IEC/IEEE 2017 CONTENTS FOREWORD . 5 INTRODUCTION . 7 1 Scope 8 2 Normative references 8 3 Terms and definitions 9 4 Abbreviated terms . 15 5 Finite-difference time-domain method basic definition . 16 6 SAR calculation and averaging
15、 17 6.1 Calculation of SAR in FDTD voxels . 17 6.2 SAR averaging 18 6.2.1 General . 18 6.2.2 Calculation of the peak spatial-average SAR . 20 6.2.3 Calculation of the whole body average SAR . 24 6.2.4 Reporting peak spatial-average SAR and whole body average SAR. 24 6.2.5 Referencing peak spatial-av
16、erage SAR and whole body average SAR . 24 6.3 Power scaling . 25 7 SAR simulation uncertainty 26 7.1 Considerations for the uncertainty evaluation 26 7.2 Uncertainty of the test setup with respect to simulation parameters 27 7.2.1 General . 27 7.2.2 Positioning . 27 7.2.3 Mesh resolution . 28 7.2.4
17、Absorbing boundary conditions 29 7.2.5 Power budget 29 7.2.6 Convergence . 29 7.2.7 Dielectrics of the phantom or body model 30 7.3 Uncertainty and validation of the developed numerical model of the DUT 31 7.3.1 General . 31 7.3.2 Uncertainty of the DUT model (d /2 or d 200 mm) . 31 7.3.3 Uncertaint
18、y of the DUT model (d part of the radiating structure where the radio-frequency currents start to support the electromagnetic fields that carry energy away from the antenna Note 1 to entry: Often the feed-point of the antenna is not accessible because of mechanical support requirements; in this case
19、 a connection point is available to inject radio-frequency energy into the antenna. Normally, the connection point is a simple connector or a waveguide flange. If not collocated, the connection and the feed-point of an antenna are interconnected by one or more sections of transmission line. By measu
20、ring the antenna impedance at the connection point, if the electrical characteristics of the transmission lines between the connection and the feed-point are known, it is possible to calculate the driving point or feed-point impedance of an antenna. 3.4 antenna feed-point impedance terminal or drivi
21、ng-point impedance ratio of complex voltage to complex current at the terminals of a transmitting antenna, or the ratio of the open-circuit voltage to the short-circuit current at the terminals of a receiving antenna 10 IEC/IEEE 62704-1:2017 IEC/IEEE 2017 3.5 attenuation decrease in magnitude of a f
22、ield quantity in the transmission from one point to another Note 1 to entry: Attenuation is expressed as a ratio. 3.6 average power P time-averaged rate of energy transfer ( ) ttPttPttd12112= (1) where P(t) is the instantaneous power Note 1 to entry: The time duration could be source related (for ex
23、ample, the source repetition period, duty cycle) or use related. 3.7 background material material or tissue which is not considered for the averaging volume Note 1 to entry: Most typically, a background material will be any lossless material, such as the free-space or air surrounding the anatomical
24、model. It also includes air enclosures or other lumina inside the body and tissues that have been excluded from averaging, for example, by user selection. 3.8 benchmark simulation simulation test specifically defined to validate simulation results based on comparison with a reference 3.9 body geomet
25、rical distribution of the dielectric properties and the mass densities of all live body tissues including body fluids Note 1 to entry: The contents of body lumina or foreign matter, such as medical implants or jewellery, are not considered as part of the body. 3.10 conductivity ratio of the magnitud
26、e of the conduction-current density in a medium to the electric field strength Note 1 to entry: Conductivity is expressed in units of siemens per metre (S/m). 3.11 conservative estimate estimate of the peak spatial-average SAR and whole-body average SAR as defined in this document that is representa
27、tive of what is expected to occur in the body of a significant majority of population during normal operating conditions of wireless communication devices Note 1 to entry: Conservative estimate does not mean the absolute maximum SAR value that could possibly occur under every conceivable combination
28、 in the human body size, shape separation from the antenna and/or vehicle. IEC/IEEE 62704-1:2017 11 IEC/IEEE 2017 3.12 coverage factor k factor that is used to obtain the expanded uncertainty from the combined uncertainty with a known probability (P) of containing the true value of the measurand Not
29、e 1 to entry: Specifically, k (combined uncertainty) = (expanded uncertainty). When k = 1, P 0,68; k = 2, P 0,95; k = 3, P 0,999. 3.13 electric field E-field vector field of electric field strength 3.14 electric field strength E at a given point, the magnitude (modulus) of the vector limit of the qu
30、otient of the force that a small stationary charge at that point will experience, by virtue of its charge, to the charge as the charge approaches zero in a macroscopic sense Note 1 to entry: This may be measured either in newtons per coulomb or in volts per metre. This term is sometimes called the E
31、-field intensity, but such use of the word intensity is deprecated, since intensity connotes power in optics and radiation. 3.14.1 electric field strength magnitude of the potential gradient in an E-field expressed in units of potential difference per unit length in the direction of the gradient 3.1
32、4.2 electric field strength magnitude of the E-field vector Note 1 to entry: The electric field strength is expressed in volts per metre (V/m) 3.15 electrical length length of a transmission medium or a transmission line, such as an antenna or a waveguide in any medium including air Note 1 to entry:
33、 Electrical length is expressed in wavelengths, radians, or degrees. When expressed in angular units, it is a distance in wavelengths multiplied by 2 to yield radians, or by 360 to yield degrees. 3.16 electromagnetic field EM field electromagnetic phenomenon expressed in scalar or vector functions o
34、f space and time, for example, a time-varying field associated with electric and magnetic forces and described by Maxwells equations 3.17 far-field region region of the field of an antenna where the angular field distribution is essentially, independent of the distance from the antenna Note 1 to ent
35、ry: In this region (also called the free-space region), the field has predominantly plane wave characteristics, i.e. the electric field strength and magnetic field strength distributions are locally uniform in planes transverse to the direction of propagation. Note 2 to entry: For larger antennas es
36、pecially, the far-field region is also referred to as the Fraunhofer region. 12 IEC/IEEE 62704-1:2017 IEC/IEEE 2017 3.18 incident wave wave, travelling through a medium, in a specific direction, which impinges on a discontinuity or a medium of different propagation characteristics 3.19 magnetic fiel
37、d H-field vector field of magnetic field strength 3.20 magnetic field strength H magnitude of the magnetic field vector Note 1 to entry: The magnetic field strength is expressed in amperes per metre (A/m). Note 2 to entry: For time harmonic fields in a medium with linear and isotropic magnetic prope
38、rties, H is equal to the ratio of the magnetic flux density B to the magnetic permeability of the medium , i.e., H = B/. 3.21 mesh discrete representation of the simulation model as a set of voxels in a regular three-dimensional Cartesian arrangement Note 1 to entry: In the scientific literature, th
39、e mesh is often referred to as “grid”. 3.22 near-field region region in the field of an antenna, located near the antenna, in which the electric and magnetic fields do not have substantial plane-wave characteristics, but vary considerably from point to point Note 1 to entry: The term near-field regi
40、on is often vaguely defined and has different meanings for large and small antennas. The near-field region is further subdivided into the reactive near-field region, which is closest to the antenna and contains most or nearly all of the stored energy associated with the field of the antenna, and the
41、 radiating near-field region. If the antenna has a maximum overall dimension that is not large compared to the wavelength, the radiating near-field region may not exist. For antennas large in terms of wavelength, the radiating near-field region is sometimes referred to as the Fresnel region. Note 2
42、to entry: For most antennas, the outer boundary of the reactive near-field region is commonly taken to exist at a distance of /2 from the antenna surface. 3.23 perfect electric conductor PEC material with infinite electrical conductivity which does not dissipate any energy 3.24 relative permittivity
43、 rratio of the complex permittivity to the permittivity of free space Note 1 to entry: The complex relative permittivity, r= /o, of an isotropic, linear, lossy dielectric medium is given by ( ) tan11rrrr0rrrrjjjj = where 0is the free space permittivity (8,854 10-12F/m); r is the relative permittivit
44、y or dielectric constant; is the conductivity in siemens per metre (S/m); tan is the loss tangent. IEC/IEEE 62704-1:2017 13 IEC/IEEE 2017 Note 2 to entry: For purposes of this document, the convention ejtis used to describe time-varying electric fields. Note 3 to entry: The permittivity of biologica
45、l tissues is frequency dependent and may be a complex tensor quantity. 3.25 penetration depth for a given frequency, the depth at which the electric field (E-field) strength of an incident plane wave, penetrating into a lossy medium, is reduced to 1/e of its value just beneath the surface of the los
46、sy medium Note 1 to entry: For a plane-wave incident normally on a planar half-space, the penetration depth is given in Formula (2): 2120r0r01121+= (2) 3.26 permeability ratio of the magnetic flux density to the magnetic field strength at a point Note 1 to entry: The permeability is expressed in uni
47、ts of henry per metre (H/m). 3.27 reactive field electric and magnetic fields surrounding an antenna or other electromagnetic devices that result in storage rather than propagation of electromagnetic energy 3.28 root-mean-square value rms positive square root of the mean value of the square of the f
48、unction taken over a given period Note 1 to entry: For a periodic function y of t, the positive square root of y is ( )212rms1dttyT=Y (3) where Yrmsis the rms value of y; t is any value of time; T is the period. 3.29 root-sum-square value rss positive square root of the sum of the squares of the ele
49、ments of a set of numbers 3.30 scattering process that causes waves incident on discontinuities or boundaries of media to be changed in direction, phase, or polarization 14 IEC/IEEE 62704-1:2017 IEC/IEEE 2017 3.31 specific absorption rate SAR time derivative (rate) of the incremental energy (dW) absorbed by (dissipated in) an incremental mass (dm) contained in a volume element (dV) of a given density ():
