  Using the supersymmetry technique, we study the localization-delocalization
transition in quasi-one-dimensional non-Hermitian systems with a direction. In
contrast to chains, our model captures the diffusive character of carriers'
motion at short distances. We calculate the joint probability of complex
eigenvalues and some other correlation functions. We find that the transition
is abrupt and occurs as a result of an interplay between two saddle-points in
the free energy functional.
