Electromagnetic Response Character of Helicopter Frequency Domain EM System above Uniform Half Space and Its Prospecting Depth
直升机频率域航空电磁系统在均匀半空间上方的电磁响应特征与探测深度

The maximum prospecting depth of the helicopter frequency domain EM system has been a problem of long controversy. It is usually considered that the maximum prospecting depth is 150 m in practical survey, but this value has been merely derived from the practical prospecting experience and cannot be regarded as a unanimously-adopted standard. Based on the uniformity half space model for this problem, the authors have worked out the theoretical formula for frequency domain electromagnetic responses of diffe- rent devices, analyzed the electromagnetic response character, discussed the relationship between the electromagnetic response character and the prospecting depth, and put forward the theoretical prospecting depth of the frequency domain EM system for different devices.