Abstract-The purpose of this paper is to analyze the influence of the metallic structures of a realistic car body frame on the specific absorption rate (SAR) produced by a cell phone when a complete human body model is placed at different locations inside the vehicle, and to identify the relevant parameters responsible for these changes. The modeling and analysis of the whole system was conducted by means of computer simulations based on the full wave finite-difference time-domain (FDTD) numerical method. The excitation considered was an 835 MHz 2 dipole located as a handsfree communication device or as a hand-held portable system. We compared the SAR at different planes on the human model, placed inside the vehicle with respect to the free space situation. The presence of the car body frame significantly changes the SAR distributions, especially when the dipole is far from the body. Although the results are not conclusive on this point, this change in SAR distribution is not likely to produce an increase above the limits in current guidelines for partial body exposure, but may be significant for whole-body exposure. The most relevant change found was the change in the impedance of the dipole, affecting the radiated power. A complementary result from the electromagnetic computations performed is the change in the electromagnetic field distribution inside a vehicle when human bodies are present. The whole vehicle model has been optimized to provide accurate results for sources placed inside the vehicle, while keeping low requirements for computer storage and simulation time.

The authors have studied a new way to design IFM (Instantaneous Frequency Measurement) subsystem. The method is based on band-stop filters. The IFM uses rectangular open loop resonators instead of delay lines. The resonance frequency is adjusted by resonator perimeter, that must be half guided wavelength, and also by coupling distance between the resonators and the main transmission line. A LSB (least significant bit) discriminator of an IFM subsystem with resolution of 62.5MHz is designed. The device has been fabricated on RT6010.2 substrate of thickness h=1.27mm. A full wave EM simulator is used to obtain the frequency response.

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