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Fig. 4. XFDTD model (numerical mesh) of the entire RF/MW exposure

system with the cell perfusion apparatus positioned at the

field maximum

plane and

of the standing wave pattern for a frequency of 1.0 GHz. (a)

plane of the three-dimensional (3-D) model are through the center of

(b)

the cell perfusion chamber.

Fig. 3.  Computer-generated drawing (SolidWorks, Concord, MA) of the

experimental setup being used for exposures at (a)  maximum and (b)  field

maximum of the standing wave pattern. Waveguide is oriented in each case to

achieve maximum coupling of  and  .

smallest possible length of perfusion tubing. All RF/MW ex-

posure parameters and temperature measurements and logging

are computer controlled using locally written LabView (version

6.3) programs.11

C. FDTD Modeling of the Exposure System

A detailed model (Fig. 4) of the entire RF/MW exposure

Fig. 5. Close-up view of the XFDTD mesh (subgrid) for the cell perfusion

system (cell perfusion apparatus and waveguide) was carefully

apparatus at the  field maximum of the standing wave. Mesh is composed of

constructed using the commercially available FDTD software

Yee cells with a side length of 0.3048 mm. (a) Center cross-sectional view and

package XFDTD.12 The waveguide and cell perfusion apparatus

(b) 3-D perspective view.

geometries were broken up into a mesh consisting of a main

grid and subgrid, respectively. The main grid was comprised of

grid Yee cells (Fig. 5). Subgridding was employed as it leads

cubical Yee cells [11] having a side length of 1.524 mm. The

to better accuracy in calculating the EM fields and SAR distri-

smaller features of the cell perfusion apparatus, as well as the

bution in the region of the glass fiber filter containing the chro-

regions in the vicinity of the waveguide top and bottom slots,

maffin cells. A Liao absorbing boundary [15] surrounded the

were represented by a subgrid of smaller cubical Yee cells of

entire solution space of the model with a thickness of eight main

side length 0.3048 mm which is one-fifth the size of the main

grid cells.

In the main grid, the brass probe launch and aluminum wave-

11National

Instruments, Austin, TX.

guide walls, including the shorting plate and coax-to-waveguide

12Bio Pro version 5.3, available from REMCOM Corporation, State College,

adapter, were modeled as perfect conductors. As in the actual

PA.