  We study electronic transport properties of disordered polymers in the
presence of both uncorrelated and short-range correlated impurities. In our
procedure, the actual physical potential acting upon the electrons is replaced
by a set of nonlocal separable potentials, leading to a Schr\"odinger equation
that is exactly solvable in the momentum representation. We then show that the
reflection coefficient of a pair of impurities placed at neighboring sites
(dimer defect) vanishes for a particular resonant energy. When there is a
finite number of such defects randomly distributed over the whole lattice, we
find that the transmission coefficient is almost unity for states close to the
resonant energy, and that those states present a very large localization
length. Multifractal analysis techniques applied to very long systems
demonstrate that these states are truly extended in the thermodynamic limit.
These results reinforce the possibility to verify experimentally theoretical
predictions about absence of localization in quasi-one-dimensional disordered
systems.
