Estimation of Electromagnetic Sensor Measurement Volume Using Combined 3D EM Simulation and Electronic Design Software

Experimental performance tests of various designs of RF and microwave sensors in laboratory or field conditions cost time and money. Digital simulations can substantially optimize the process of reaching the research objective. The paper presents the application of using two digital simulation techniques - 3D electromagnetic and transient states analysis to estimate the measurement volume of a soil moisture and electrical conductivity profile probe working in transmission mode. First, 3D simulation software was applied to collect the S₁₂ transmission element of scattering matrix that describes the interaction between the sensor and the measured material. Next, the electronic simulation software uses the S₁₂ element for calculating the travel time of an electric pulse along the sensor/material combined structure. It was found that for the given geometry of the applied profile probe the measured soil thickness is about twenty millimeters around the tested profile probe, the internal part of the probe body has negligible effect on measurement results and the transmitted signal amplitude corresponds to the soil electrical conductivity.