The invention provides a numerical calculation method of an
electromagnetic field response of a
dipole source at an arbitrary position under layered geological conditions. The calculation method comprises the steps of: step S100, defining stratums according to the position of the
dipole source in the layered stratums; step 200, performing
orthogonal decomposition on the
dipole source; step S300, deriving a Lorentz
vector potential expression generated by the unit
dipole source in each stratum; step S400, deriving an
electromagnetic field expression in each stratum according to the Lorentz
vector potential expression; step S500, calculating a Bessel functional integration in the
electromagnetic field expression by adopting a
Gaussian extrapolation method to obtain a numerical solution of the electromagnetic field; step S600, and acquiring the electromagnetic field response of the
dipole source by multiplying the numerical solution by a
dipole source moment. The calculation method utilizes the expressions that Lorentz
vector potential between the adjacent stratums satisfy, utilizes the particular solution of the stratum where the dipole source locates for circulating
recursion to obtain the Lorentz vector potential expressions of all stratums, and obtains the electromagnetic field expression by means of the Lorentz vector potential, finally calculates the Bessel functional integration in the electromagnetic field expression by adopting the
Gaussian extrapolation method to obtain the electromagnetic field response of the dipole source, and has the advantages of clear theory and high calculation precision.