Fig. 1

Equivalent circuit schematic of sensor coupling with rock sample⁴⁴. U_S is the equivalent output voltage of the microwave resonance oscillation signal, R is equivalent total resistance, L₀ is the sum of the equivalent of sensor inductance and distribution parameter, and C₀ is the sum of the equivalent of the distribution parameters of sensor and resonance oscillation circuit capacitance, L₁ is distributed inductance after the tested sample is loaded, analogously, C₁ is distributed capacitance after the tested sample is loaded, and U₀ is resonance vibration output voltage. And I is total current, I₁ is load current, I₀ is no-load current, U_R is equivalent total resistance voltage.