摘要
A fixed artificial source(greater than 200 kW) was used and the source location was selected at a high resistivity region to ensure high emission efficiency. Some publications used the "earth-ionosphere" mode in modeling the electromagnetic(EM) fields with the offset up to a thousand kilometer, and such EM fields still have a signal/noise ratio of 10-20 dB. This means that a new EM method with fixed source is feasible, but in their calculation, the displacement in air was neglected. In this work, some three-layer modeling results were presented to illustrate the basic EM fields' characteristics in the near, far and waveguide areas under "earth-ionosphere" mode, and a standard is given to distinguish the boundary of near, far and waveguide areas. Due to the influence of the ionosphere and displacement current in the air, the "earth-ionosphere" mode EM fields have an extra waveguide zone, where the fields' behavior is very different from that of the far field zone.
A fixed artificial source （greater than 200 kW） was used and the source location was selected at a high resistivity region to ensure high emission efficiency. Some publications used the “earth-ionosphere＂ mode in modeling the electromagnetic （EM） fields with the offset up to a thousand kilometer, and such EM fields still have a signal/noise ratio of 10–20 dB. This means that a new EM method with fixed source is feasible, but in their calculation, the displacement in air was neglected. In this work, some three-layer modeling results were presented to illustrate the basic EM fields’ characteristics in the near, far and waveguide areas under “earth-ionosphere” mode, and a standard is given to distinguish the boundary of near, far and waveguide areas. Due to the influence of the ionosphere and displacement current in the air, the “earth-ionosphere” mode EM fields have an extra waveguide zone, where the fields’ behavior is very different from that of the far field zone.
作者
李帝铨
谢维
底青云
王妙月
LI Di-quan XIE Wei DI Qing-yun WANG Miao-yue(Key Laboratory of Metallogenic Prediction of Nonferrous Metals of Ministry of Education （Central South University）, Changsha 410083, China School of Geosciences and Info-Physics, Central South University, Changsha 410083, China Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China)
基金
Projects(41204054,41541036,41604111)supported by the National Natural Science Foundation of China
