GprMax的理论基础是时域有限差分(FDTD)方法。时域有限差分方法直接将Maxwell方程作差分离散，利用二阶精度的中心差分近似把Maxwell方程中的微分算符直接转换为差分形式，在空间和时间上对电场和磁场交替间隔取样，使计算过程完全模拟电磁波逐步传播以及与目标物体相互作用的过程。-GprMax is based on the theory of the finite difference time domain (FDTD) method. The finite difference time domain method directly will Maxwell equation of discrete difference, using second order precision of the central difference in the equations are Maxwell approximate differential operator directly convert difference forms, in the space and time of electric field and magnetic field on alternate sampling interval, making the calculation process simulation electromagnetic wave propagation and completely step by step and target object interaction process.