In order to understand induction response law of a finite-length of buried cable to the external electromagnetic field

based on the transmission line theory

formulas of induced voltage and current at cable ends are deduced by fast Fourier transform and inverse transform technique

and the change law of induced current is analyzed. The results show that: ① the induced current decreases with the increase in cable’s underground depth

earth conductance or relative permittivity; ② the induced current keeps stable when the conductance of the cable conductor increases; ③ when the cable length is less than 30 m

the peak value of the induced current increases with the increase in cable length

while the peak value decreases with the increase in cable length if the length is over 30 m; ④ time delay in the induced current waveform is observed with the increase in cable length; ⑤in the range of [0

90° ]

the induced current decreases with the increase in polarization angle or orientation angle

but increases with the increase in pitching angle;⑥if one terminal impedance Z1keeps constant and the other terminal impedance Z2increases

the induced current in the Z2end tends to decrease

while if Z2is constant and Z1increases

the induced current in the Z2end keeps stable.