Calibration Of Electric Field Probes Research Articles

Calibration of electric field probes in GTEM cell using reference antenna method

Calibration of electric field probes in a GTEM cell is carried out using the reference antenna method. To determine the effectiveness of the calibration, we compared our results with those of calibration in an anechoic chamber from 1 to 6GHz. Each electric field probe had three elements, one of which was used to calibrate the other two. The calibration factors in the GTEM cell agree well with those in the anechoic chamber. Therefore, the GTEM cell is as effective as the anechoic chamber for calibrating electric field probes with the same type of probe and helps save more measurement time and effort.

Calibration of electric field probes with three orthogonal elements by standard field method

Electric field probes with three orthogonal elements were calibrated from 1-6GHz by the standard field method in an anechoic chamber. A special jig was constructed for setting and calibrating a Δ-beam-type probe. Calibration factors of the probes were obtained for each element using this jig. To reflect the future revision of IEC 61000-4 series, uncertainty in the calibration factors was investigated to improve calibration quality and determine the factors affecting calibration. We found that fluctuation in the power transmitted from a high power amplifier and the imperfection of the anechoic chamber were the most important factors affecting uncertainty.

Design and Calibration of Electric Field Probe to the Frequency Range of 2 to 3 GHz

Two probes designed for electric field measurements were constructed by two semi-rigid coaxial cables, through a non-expensive simple handmade process. Both probes were also simulated by a program specifically used for microwave devices and calibrated following international standards for the frequency range of 2 to 3 GHz. The simulations and the calibration procedure, which was performed in a semi-anechoic chamber, evaluated the measured voltage, performance factor and S11 of each probe. The simulated and experimental results were compared. The return loss parameter was used to determine the maximum operation frequency. The results showed that even simple probes as the ones constructed in the present work, when properly calibrated, can be used to measure with good accuracy the magnitude of the electric field in the considered frequency range.

Design and calibration of electric field probes in the range 10 - 120 MHz

In view of potential thermal hazards, there is a need to determine the specific absorption rate (SAR) distributions associated with radiofrequency coils used in magnetic resonance imaging (MRI) (typically 10 - 120 MHz). Electric field (E-field) distributions in tissue-equivalent phantoms may be determined using a probe comprising a dipole antenna and a detector. The geometry of the dipole dictates the sensitivity of the device, thus two designs are discussed in this paper. Both probes are compact, have a spatial resolution of , operate at MR frequencies and have a response independent of the dielectric characteristics of the phantom material. Calibration of these probes requires a system capable of producing a known E-field both in air and in a tissue-like medium at frequencies between 10 and 120 MHz. Transverse electromagnetic wave (TEM) cells answering these specifications are described and the calibration procedure outlined. Accurately calibrated E-field probes can make field measurements in phantoms which can be used to verify predictions from numerical models. These numerical techniques may then be used to predict E-fields, and hence SAR, in patients.