关键词: 线源, 近区(过渡区), 全区视电阻率, 层状介质

Abstract: The preliminary research result of electromagnetic prospecting of the near field(transition region) of long grounded wire in frequency domain is presented in this paper.And the full-region apparent resistivity is defined and calculated from some modeling results including the response of half space and the response of stratified space.From the results,we get the conclusion that the full-region apparent resistivity in the above situation defined from horizontal electric field and vertical magnetic field can yield a good outcome of underground electric structure.The full-region apparent resistivity calculated by using dichotomy after joining horizontal magnetic field and horizontal electrical field together can also reflect the change of electric structure underground.The full-region apparent resistivity defined by using a single component in the near field matches well with the single dimensional MT curve,therefore,mature MT inversion technology can be used to do the inversion of the near field,thus transforming the function with source to non-source types.It is available to prospect in the near field(transition region) with long grounded wire,even there are still some pending problems.

Key words: line source, near field(transition region), full-region apparent resistivity, stratified media