  We consider a two-band superconductor with relative phase $\pi $ between the
two order parameters as a model for the superconducting state in
ferropnictides. Within this model we calculate the microwave response and the
NMR relaxation rate. The influence of intra- and interband impurity scattering
beyond the Born and unitary limits is taken into account. We show that,
depending on the scattering rate, various types of power law temperature
dependencies of the magnetic field penetration depth and the NMR relaxation
rate at low temperatures may take place.
