Abstand zw. exponiertem Objekt und Expositionsquelle
The exposure system for 12 rats consisted of three distinct arrays of four loop antennas printed on dielectric substrate, two for real and one for sham exposure (blinded). It was assembled in a wooden rack with RF-absorbing panels inserted between the arrays and on the four sides of the rack. Rats were placed close to a different antenna (in the same array) each day to obtain a uniform distribution of exposure.
Animals were held in individual Perspex jigs with cylindrical tubes with a cone-shaped head end and a lockable piston in the tail end. Each antenna was held perpendicular to the head surface over the right ear of each rat in contact with the external side of the Perspex jig with a total distance from the cochlear system of about 8-10 mm.
Fields at 50 Hz in the set-up were B = 0.05-0.08 µT and E = 0.7-1.7 V/m.
Mess- und Berechnungsdetails
Numerical dosimetry was performed using a commercial FDTD code on a realistic model of the rat head with five fundamental tissues and a loop antenna positioned at 5 mm from the head surface. Measurements were performed using miniature probes on homogeneous phantoms and in the inner ear of a rat's cadaver using the power pulse method and a fluoroptic thermometer. Numerical and experimental dosimetry showed a good agreement.