介电颗粒在与入射电磁波的相互作用过程中会产生Mie 谐振，导致谐振频率附近的微波被吸收，此时电磁场的能量会聚集在介电颗粒附近，若周围有微小扰动( 例如金属反射表面的细小裂缝) ，会引起谐振频率的明显变化. 通过矢量网络分析仪测量电磁波反射系数，并记录吸收峰的频率变化，可以获取裂缝的信息. 实验中对不同尺寸的裂缝进行了探测，可以归纳出两条规律: 对同一深度( 或宽度) 的裂缝，介电颗粒谐振频率随着裂缝宽度( 深度) 增大向低频移动，并且谐振频率的变化率也随裂缝宽度( 深度) 增大而减小.

During the interaction between dielectric particles and incident electromagnetic waves，Mie resonance is generated，which results in the absorption of microwave near the resonance frequency. At this time，the energy of electromagnetic field will be gathered near the dielectric particles. If there are small perturbations around the dielectric particles，such as small cracks on the reflecting surface of metal，the resonance frequency will change

obviously. The network analyzer can measure the reflection coefficient of electromagnetic wave and record the frequency change of absorption peak to obtain the information of cracks. In the experiment，cracks of different sizes are detected，and two rules can be concluded: for cracks of the same depth ( or width) ，the resonance frequency of dielectric particles decreases with the increase of crack width ( depth) ，and the change rate of resonance frequency decreases with the increase of crack width ( depth) .