Taking into account the coupled interactions among wind velocity, sand movement, and the electric field, we develop a general theoretical model for calculating the electric fields produced by charged sand particles in the three sand movement types, saltation, suspension and creep, quantifying the electric field of a point charge by Coulomb's law. The numerical results of the electric field are in good agreement with both the field data and the wind tunnel experimental results. The profile of the electric field intensity produced by charged particles in windblown sand flux is quantitatively analyzed in detail and compared with those generated by charged particles only in the saltation layer or in the creep layer. The results demonstrate that the profile of the electric field produced by charged particles in one sand movement type is different from that by those in other types and that the signs of the charge acquired by the particles also alter the features of the profile. Finally, the effects of the wind velocity and the charge of the windblown sand particles on the electric field intensity are discussed.