To observe the reflecting properties of spherical electromagnetic waves in the presence of conducting half - space so as to provide a basis for the parameter selection in detecting system, an active electromagnetic detecting mathematic model under the circumstance of radiating coils placed vertical to the reflecting surface is set up in this paper. The radiating electromagnetic waves in practical use are spherical waves, so first spherical waves are transformed into the nestification of planer waves using Sommerfeld Formula. Then Hertz vector method is employed in deducing the expression of the reflective intensity under this circumstance. Through the comparison with idealistic conducting surface, it is diseussod how frequency and electromagnetic parameter influence the reflective intensity. To verify the mathematic model above, a simple apparatus is designed. In experiments, reflective magnetic intensities when the reflecting surface is placed in different ranges are measured, and the results generally agree with the theoretic calculations. With some necessary signal detecting eircuits added, the apparatus used in the experiments can act as a practical active electromagnetic system.%研究主动电磁探测系统中辐射波在平面金属界面上的反射特性,以便为检测系统的参数设置提供依据,针对辐射线圈垂直于平面反射面的检测情形,建立了主动电磁探测系统数学模型.为了验证上述数学模型的正确性,利用索末菲公式将球面波转化为平面波的叠加,并通过赫兹矢量法推导了检测情形下反射磁场强度的表达式,与理想导体平面相比,讨论了反射强度与辐射波频率和反射面电磁参数的关系.并对反射面位于辐射器前方不同距离时的反射磁场强度进行了仿真测量,结果与理论计算值基本一致.证明实验装置可作为主动电磁探测系统应用在工程中.
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