Low Frequency

Electric Field

Probes

Low Frequency

Magnetic Field

Probes

This provides for the independence of probe orientation relative to the polarization of the field. The instantaneous charge distribution on adjacent cold junction elements produces a potential difference across the thin-film resistive thermocouples and a resultant dissipation of energy in these films. As the frequency increases, the phase difference between the potentials developed in adjacent junctions also increases the open circuit voltage.

The Model 8764D operates from 100 kHz to 300 MHz. It contains three orthogonal displacement energy sensors with diode detectors. This unique design has much lower impedance than traditional dipole designs. The major advantage is the greatly reduced interaction between the meter and probe, the human body making the measurements, and the RF field.

The Model 8782D uses an “active antenna” design to accurately measure RF fields as low as 3 kHz over a 60dB dynamic range.

These probes are responsive to the H-Field component. Each of the three mutually perpendicular coils in every probe has a diameter of 3.5 inches (8.9 cm), consists of multiple turns and is series-resonated somewhat below the low frequency end of the band. The RF current induced by the “H” field dissipates power in the thermocouple elements, heats the hot junctions and provides a DC output voltage proportional to the square of the induced current. Circuitry is added to minimize high frequency out-of-band responses typical in many H-field probe designs.

Appendix B Theory of Operation

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