电磁波衰减系数特性分析

The Attenuation Characteristics of Electromagnetic Wave

为了探索勘探深度大且分辨率高的电磁勘探技术,采用数值计算的方法研究了电磁波在1～1015Hz整个波谱范围内的衰减规律.计算了多种模型下,电磁波衰减系数的频率响应曲线,得到了电阻率分别为50、100、150、200、250、300、350、400、450、500Ω·m共10条曲线.这些曲线共同揭示了一个规律,从低频到高频,衰减系数随频率的增大而急剧增大;到一定频率后,波衰减系数趋于稳定;频率增大到某个阀值后,衰减系数急剧下降.在任意给定的电阻率下,频率超过某一阀值频率后,电磁波呈慢衰减或基本不衰减特性.因此,大于阀值的高频电磁波可进行大深度高分辨率勘探.

In order to develop new electromagnetic exploration techniques with high resolution and deeper exploration ability,the characteristics of electromagnetic wave attenuation rules with the whole spectral range within 1~1015Hz was studied by using numerical simulation method.The frequency-response curve of electromagnetic wave attenuation coefficient was calculated by using many models,the curves with resistivity being 50,100,150,200,250,300,350,400,450,500Ω·m were obtained respectively.These curves of attenuation coefficient revealed a common rule.From the high frequency to the low one,the attenuation coefficient increases sharply with the increase of frequency.At certain frequency level,the attenuation coefficient keeps constant.The attenuation coefficient sharply decreases when frequency increases to a certain threshold.The electromagnetic wave does not decay or remains constant when the frequency reaches a threshold value in any given resistivity.Therefore the high frequency electromagnetic wave which is more than a threshold value can be used for deeper and high-resolution exploration.