EMF measurement

In fact, probes should not perturb the electromagnetic field and must prevent coupling and reflection as much as possible in order to obtain precise results.

A mono-axial, omnidirectional probe is a device which senses the Electric (short dipole) or Magnetic field linearly polarized in a given direction.

There are other meters which can measure fields alternating at as low as 20 Hz, however these tend to be much more expensive and are only used for specific research purposes.

In fact, a passive receiving antenna collects energy from the electromagnetic field being measured and makes it available at a RF cable connector.

This signal then goes to the spectrum analyzer but the field characteristics can be someway modified by the presence of the cable, especially in near-field conditions.

On the other hand, an effective solution is to transfer on an optical carrier, the electric (or magnetic) field component sensed with an active probe.