Abstand zw. exponiertem Objekt und Expositionsquelle
The anechoic chamber was 2.44 x 2.44 x 3.05 m. A small climate-conditioned cubicle was created by a 5-cm thick Styrofoam partition. The dipole antenna was mounted in a 90° aluminium corner reflector.
Subjects wearing a bathing suit sat in a light plastic chair with their back towards the antenna. The electric field vector of the incident plane wave was aligned with the long axis of the subject's body (E-polarization).
Power densities (PD) specified above were determined with the E-field probe placed on the antenna boresight at the location of the subject's center back. Verification measurements of these PDs were made at 2- to 3-week intervals during the course of the study.
Mess- und Berechnungsdetails
Forward and reflected powers were monitored by power meters. Field uniformity at the subject's location was determined over a 60 x 90 cm plane centered on the boresight and at 130 cm from the antenna using a broadband isotropic radiation detector fitted with an E-field probe. PD across the central 20 x 40 cm portion of this plane showed a 14% nonuniformity with the chair present. Dosimetric evaluations were conducted on a 70-kg soft plastic mannequin model, 174 cm tall, filled with simulated muscle tissue and placed on the chair with its back at a distance of 102 cm from the antenna. After equilibration, the model was irradiated for 10 min at three PD values. The maximum surface SAR of 0.32 W/kg per mW/cm² was calculated from the greatest temperature rise occurring at the lower back [Chou et al., 1996]. A second set of temperature readings was taken for comparison with the probes inserted 2 cm below the surface and exposure for 45 min. SAR could, however, not be calculated from these because the E-field was unknown for the points.
Unter keiner Befeldungs-Bedingung traten Veränderungen bei der metabolischen Wärme-Produktion auf. Starke Erhöhungen bei der Schwitzrate am Rücken und auf der Brust, die direkt mit der Umgebungstemperatur und den Leistungsflussdichten verbunden waren, kühlten die Haut und stellten die wirksame Regulierung der tiefen Körpertemperatur innerhalb von 0.1°C vom normalen Wert sicher.