**4. Calculation Results of the Three-Dimensional Chargeable Body Model**

The phenomenon of the inverse sign (IP effect) often appears in GREATEM. Most researchers focused on the influence of the IP parameters. However, in addition to the IP parameters, the system parameters of GREATEM also have an impact on the IP effect. In this section, we mainly analyze the effect of the system parameters, and we provide a theoretical basis for the field measurements.
