  This paper is concerned with a numerical method for a 3D coefficient inverse
problem with phaseless scattering data. These are multi-frequency data
generated by a single direction of the incident plane wave. Our numerical
procedure consists of two stages. The first stage aims to reconstruct the
(approximate) scattered field at the plane of measurements from its intensity.
We present an algorithm for the reconstruction process and prove a uniqueness
result of this reconstruction. After obtaining the approximate scattered field,
we exploit a newly developed globally convergent numerical method to solve the
coefficient inverse problem with the phased scattering data. The latter is the
second stage of our algorithm. Numerical examples are presented to demonstrate
the performance of our method. Finally, we present a numerical study which aims
to show that, under a certain assumption, the solution of the scattering
problem for the 3D scalar Helmholtz equation can be used to approximate the
component of the electric field which was originally incident upon the medium.
