Polarization of a High-Frequency Electromagnetic Field in the Tensor CSRMT Method

The paper considers different modes of producing a "rotating" field for the implementation of the tensor CSRMT method. We analyzed changes in the direction of polarization of a high-frequency electromagnetic field of a grounded wire used as a source in the CSRMT method, depending on the frequency and wire parameters. Modelling results and field experiments show that even with single transmitter's wire the direction of horizontal polarization of the electromagnetic field varies significantly at frequencies above 100 kHz. However, in this case the direction of polarization of the electric and magnetic fields remains constant in time, and single transmitter's wire is not sufficient for tensor measurements. When two mutually perpendicular transmitter's wires are used, tensor measurements become possible by connecting the transmitter to one and then to the other wire consequently. If two independent transmitters with identical output current frequencies are simultaneously connected to two wires, a "rotating" field is produced at frequencies of a ten to hundred kilohertz as a result of the non-identity of the lines and groundings. To produce a "rotating" field at frequencies below 10 kHz, it makes sense to use two transmitters running in parallel with a slightly different output current frequency. The analyzed modes of producing a "rotating" field and performing tensor measurements provide identical values of components of the impedance tensor and the Wiese-Parkinson vector.