Electric field probes for cellular phone dosimetry

Miniature implantable electric field probes (E-field Probes) enable the measurements of microwave electric fields induced in biological subjects by relatively low level exposures. Using these instruments, the rate of energy deposition (Specific Absorption Rate or SAR) can be determined throughout models or actual bodies of laboratory animals and humans exposed to emissions from cellular phones and other radiators. E-field probes consist of an array of three electrically short dipole antennas. Each antenna has the following components: a diode detector, a dielectric coating and mechanical support, a highly resistive balanced transmission line, a differential amplifier, and a detected signal processor. Most modern microwave safety standards and several medical applications of microwave energy require SAR data to be measured. E-field probes are unique in that they are sensitive enough to measure the local SAR using actual low-power radiation sources such as a handheld cellular phone. A spatial map of the local SAR can be obtained by mechanically scanning a model of a biological subject filled with a lossy dielectric liquid that simulates body tissues. Sensitivities of one microwatt/gram (one mW/kg) are practical in such systems