  This paper is dedicated to an application of a quantum wave impedance
approach for a study of infinite and semi-infinite periodic systems. Both a
Dirac comb and a $\delta-\delta'$ comb as well as a Kronig-Penney model are
considered. It was shown how to reformulate the problem of an investigation of
mentioned systems in terms of a quantum wave impedance and it was demonstrated
how much a quantum wave impedance approach simplifies studying these systems
compared to other methods. The illustation of such a simplification was
provided by application of classical approach, transfer matrix technique and a
quatum wave impedance method for solving Kronig-Penney model.
