  We show that electron localization is generic in a linear chain of identical
simple quantum wire loops with equal arm lengths in the presence of either a
perpendicular magnetic field or the spin-orbit interaction, and has less to do
with the shapes of the loops. We calculate the transfer matrices for a general
simple loop scatterer in the presence of these effects. Based on the knowledge
of the transfer matrices, we thus provide a criterion for the occurrence of the
localization and present a simple formalism to integrate the transmission
probability over the injection wave vector of electron.
