Physical limitations on the measurement of transient fields in air and in dissipative media using electric and magnetic probes

The properties of electric and magnetic probes for the measurement of transient electromagnetic fields in air and in dissipative media are discussed briefly. It is shown that the effective height of an electrically small loop is independent of the ambient medium. This is also virtually true for a thin electrically short dipole (or monopole). If the open-circuit voltage of a magnetic probe can be measured accurately, it is possible (in principle) to reconstruct the time history of the incident magnetic field, even if the loop is immersed in dissipative media of unknown characteristics. The time function of the open-circuit voltage of an electric probe is essentially a replica of the time history of the incident electric field, even when the probe is immersed in a dissipative medium. For impedance-loaded probes the equivalent circuit of the receiving antennas involves the source impedances of the probes. These depend on the properties of the environment. In a dissipative medium a distortion of the response to transient fields results.