Meaning
Electromagnetic field measurement relies on specialized sensors that respond uniformly to electric field vectors from all directions. An isotropic e field probe achieves this multi-directional response by integrating three orthogonal sensor elements in a single housing. These elements measure the individual orthogonal field components to calculate the total electric field magnitude.
Laboratories deploy this tool inside phantom shells to obtain accurate specific absorption rate measurements.
Sensor Construction
Miniaturized dipoles are arranged in a triangular or orthogonal layout around a central axis to minimize mutual coupling. Each dipole in the isotropic e field probe has a dedicated resistive line that carries the rectified voltage to the data acquisition system. The spherical reception pattern must remain highly symmetrical to avoid measurement bias as the scanner rotates the probe.
This spatial arrangement reduces dependency on polarization angles during dense spatial scans.
Calibration Sequence
Every sensor undergoes factory calibration in a waveguide or a reference field to establish its sensitivity coefficients. During this sequence, the isotropic e field probe is rotated in a known electric field to map its axial and spherical isotropy deviation. These correction factors are stored in the probe configuration file for real-time application.
This calibration ensures that measurement uncertainty remains within the strict bounds required for laboratory certification.
Field Assessment
Testing procedures demand high probe sensitivity to capture faint localized emissions. This makes the isotropic e field probe indispensable when assessing complex multi-transmitter mobile devices.
