This paper proposes a head-local-exposure system using a figure-8 loop antenna for 2-GHz band operation. This system allows us to observe biological effects through microcirculation of the rat brain simultaneously with exposure through a cranial window, i.e., the window made by transparent glass and implanted on the surface of the rat brain. The specific absorption rate (SAR) in a rat exposed to microwaves due to the new exposure system is estimated numerically and experimentally. The ratio of averaged SAR between the target area, which is the brain's surface just under the cranial window, and the whole body is about 59 for the 8-week rat model and 13 for the 2-week rat model. This antenna achieves local exposure for the rat brain for 2-GHz band operation.

This paper presents a simple abdomen model of pregnant women and the evaluation of the specific absorption rate (SAR) inside the proposed model close to normal mode helical antennas (NHAs), which are replacing the portable radio terminals for business at 150 MHz. First, dielectric properties of amniotic fluid and those of fetus of rabbit, which have about the same electrical properties as human, are measured. As a result, the conductivity of amniotic fluid is 1.8 times and that of fetus is 1.3 times higher than that of adult muscle at 150 MHz. The result also suggests the modeling of pregnant women including the amniotic fluid and the fetus is necessary. Next, a simple abdomen model of pregnant women based on the measurements of magnetic resonance (MR) images of Japanese women in the late period of pregnancy is proposed. Finally, the SAR inside the proposed abdomen model close to 0.11λ and 0.18λ NHAs is calculated using the finite-difference time-domain (FDTD) method. As a result, we have confirmed that the 10-g average SAR in the fetus is sufficiently less than 2 W/kg, when the output power of NHAs is 5 W, which is the maximum power of portable radio terminals in Japan.