Biomedical Engineering Reference
In-Depth Information
Fig. 7.6 Antenna far field
gain plot at 4 GHz (Gain
(dBi) vs. Phi (degrees))
Far Field Gain Abs (at Phi=60)
Theta/ Degrees vs. dB
using both the FCC regulated IR-UWB pulse and an IR-UWB pulse with a power
spectrum that is higher than the FCC spectral mask in order to assess and compare
the SAR variations.
7.3.2 SAR, SA Variations due to the Operation
of IR-UWB-Based WCE Devices
SAR and temperature simulations are carried out for different signal power levels
of the WCE antenna placed at a fixed position. Figure
7.7
presents the SAR
variations for the first scenario. Figure
7.7
a shows the SAR variation for an IR-
UWB pulse with a total in-band signal power level which lies within the FCC
spectral mask of -41.3 dBm/MHz. The SAR variation in Fig.
7.7
b corresponds to
an IR-UWB pulse that causes a maximum 10 g averaged SAR value of 2 W/kg
which is the ICNIRP allowed SAR limit. Figure
7.7
c depicts the SAR variation for
an IR-UWB pulse that results in a signal power level just outside the human body
to lay within the FCC regulated spectral mask. The maximum SA is calculated for
each scenario using (
7.9
). An IR-UWB pulse width of 2 ns is used for the cal-
culation of the SA. The in-band power of the IR-UWB pulses for the three dif-
ferent scenarios is varied by changing the pulse amplitude. The total in-band
power for each simulation is calculated by integrating the power spectrum of the
IR-UWB pulse in the frequency band of 3.5-4.5 GHz. The color scale in Fig.
7.7
