6.1.4    SAR

QW-3D enables calculations of specific absorption rate (SAR). SAR is calculated only in FDTD cells filled with media, which are declared in the Input Interface simultaneously as:

• lossy (s >0 or s_m >0),

• dense (r >0).

Please note that density should be specified in [g/cm³].

SAR in a particular FDTD cell is calculated from dissipated power density pd, extracted in that cell, and density of its filling material. The unit for SAR is [W/kg]. Please note that when converting dissipated power density to SAR, in case of FDTD cells filled with more than one medium, QW‑Simulator performs conformal averaging of density between materials filling a cell. Field components included in calculation of SAR picture shows the field components included in calculation of SAR, centred at the cell centre marked by the black cross.

The calculations of the SAR are somewhat different in QW-V2D than in QW-3D, due to its specificity. Similarly as in the case of dissipated power, SAR is calculated with respect to a ring volume. SAR in a particular FDTD ring is calculated from dissipated power density pd, extracted in that ring, and density of its filling material.

The meaning of ring in QW-V2D is as follows:

ring=2*π*r*dx*dy

where dx, dy stand for the cell size in X and Y direction, respectively, and r is the radius of the ring associated with a middle of the cell along Y axis.

Field components included in calculation of SAR in the presented cell, centred at the cell centre marked by the black cross.

SAR= f (_k,m,lE_x,  _k,m-1,lE_x,  _k-1,m,lE_y, _k,m,lE_y, _k,m,l-1E_x, _k,m-1,l-1E_x, _k-1,m,l-1E_y, _k,m,l-1E_y, _k-1,m-1,lE_z, _k,m-1,lE_z, _k-1,m,lE_z, _k-1,m-1,lH_x, _k,m-1,lH_x, _k-1,m-1,lH_y, _k-1,m,lH_y, _k,m,l-1H_z, _k,m,lH_z)

Note that k,m,l are the cell indexes.

In QuickWave, SAR values can be obtained as:

• The 1D distribution displays that allow time domain monitoring of SAR along any line parallel to one of the coordinate axes or deliver SAR in a particular point of the circuit versus time. The 1D monitoring delivers instantaneous and envelope (time-maximum) values of the SAR and is available in 1D Fields window. General discussion concerning the 1D distribution monitoring is given in Monitoring along specified line and versus time.

• The time-dependent 2D distribution of the SAR (in areas declared as lossy and dense), available for every FDTD layer along each of three axes. The distribution of SAR is available in the 2D/3D Fields Distribution window. The user can view instantaneous, time-maximum, and time-average values of SAR.

• The 3D display of time-dependent SAR distributions. This feature is available in the 2D/3D Fields Distribution window and it enables viewing instantaneous, time-maximum, and time-average values of SAR.

QuickWave offers also some advanced options for supressing SAR calculation.