电磁层析成像中激励电流频率的选择

摘要

The frequency of exciting current affects the design of hardware circuit and quality of reconstructed images in electromagnetic tomography.According to the skin effect and skin depth formula of high frequency current,the law of excitation frequency for different test object is concluded.The advantage of electromagnetic tomography is introduced simply.The relationship curve between exciting current frequency,conductivity and the skin depth is draw,from which the frequency scope for common test object is given.With the same test object,the same position,and the same orientation,different reconstructed images are obtained in different exciting current frequency.It can draw a conclusion that metal medium need low frequency to excite,kHz or smaller,on the contrary,biological tissue and moisture content need high frequency,MHz or higher.%电磁层析成像技术中激励电流的频率影响硬件电路的设计难度和图像重建质量,根据高频电流的趋肤效应和趋肤深度的计算方法,总结出不同被测介质的激励频率规律.简单介绍了电磁层析成像技术的优点,根据其物理模型和高频电流趋肤效应计算方法,绘制激励电流频率和非导磁性介质导电率、趋肤深度的关系,给出了常见不同材质被测物激励频率的大致范围,并比较了相同被测物、相同物场空间位置和相同激励-检测方向下,不同频率激励电流下获得的图像重建结果,得出结论,金属需要较低的激励频率,kHz或者更小.而像生物组织和含水物体等电导率介质,需要MHz范围的频率.