  Infinitesimal electric and magnetic dipoles are widely used as an equivalent
radiating source model. In this paper, an improved method for dipole extraction
from magnitude-only electromagnetic-field data based on genetic algorithm and
back-and-forth iteration algorithm [1] is proposed. Compared with conventional
back-and-forth iteration algorithm, this method offers an automatic flow to
extract the equivalent dipoles without prior decision of the type, position,
orientation and number of dipoles. It can be easily applied to
electromagnetic-field data on arbitrarily shaped surfaces and minimize the
number of required dipoles. The extracted dipoles can be close to original
radiating structure, thus being physical. Compared with conventional genetic
algorithm based method, this method reduces the optimization time and will not
easily get trapped into local minima during optimization, thus being more
robust. This method is validated by both simulation data and measurement data
and its advantages are proved. The potential application of this method in
phase retrieval is also discussed.
