An analytical expression for the near field of a circular piston radiator

Abstract Approximate results are derived, in a closed form, for the field of a circular piston radiator. The results are based on making Fresnel approximations in the evaluation of the radiation integral and, as such, are not applicable in the immediate vicinity of the radiator. Results obtained are compared with numerical computations based on an exact solution of the field, showing very good agreement within the near field.