the current distribution must be modeled correctly.

Complex Dipole Antenna Model

While it may not be possible to model the exact shape

and size of all the RF current contributing components,

FDTD provides the flexibility for modeling complex

their effects on the near-field distribution produced by

structures with the high degree of fidelity needed to

the overall device must be correctly represented and

evaluate antenna performance in near-field exposure

accounted for. The thickness and dielectric properties of

conditions. Amplifier source matching is sensitive to

the phantom plastic, its shape and size should be

antenna performance where output loading and power

modeled figure 7 to allow the dipole to be positioned

reflection are closely related to the antenna-matching

precisely, ensuring correct energy distribution and

components of the equivalent model in figure 3. Since

coupling onto the phantom. The antenna must also

SAR can be highly dependent on the surface current

resonate to ensure correct antenna current distribution.

distribution on the device (resonant area) every effort

Mismatched antenna impedance will result in incorrect

was made to model the antenna and critical radiating

current distribution on the rest of the device test

structures of the circuit with optimized accuracy of the

configuration.  The  electric  and  magnetic  field

antenna matching components. The geometry and fine

distributions that can be expected are shown in figures 4

features of the complex dipole antenna in figure 2

& 5 respectively.

require special consideration so as to define the optimal

cell size (discussed later) and object orientation that

would reduce errors (known) to a minimum.

Electric Field Distribution

Complex Dipole Antenna (FDTD) Model

figure.4

Magnetic Field Distribution

figure.2

Equivalent Model of Dipole

Figure.5

figure.3

Antenna impedance matching components and all other

elements within the circuit that can potentially change