  The microwave properties of polycrystalline MgB2 thin films prepared by the
so-called in-situ method are investigated. The characterization of the films at
microwave frequencies was obtained by a coplanar resonator technique. The
analysis of the experimental data results in the determination of penetration
depth, surface impedance and complex conductivity. The aim of this work is to
set the experimental results in a consistent framework, involving the two-band
model in the presence of impurity scattering. The energy gaps are calculated
and the contribution of intra- and inter-band scattering is considered. From
the comparison between the calculated gap values and the experimental data it
turns out that the temperature dependence of the penetration depth can be
accounted for by an effective mean energy gap, in agreement with the
predictions of Kogan et al. [Phys. Rev. B 69, 132506 (2004)]. On the other
hand, the temperature dependence of the real part of the microwave conductivity
and of the surface resistance is accounted for by the single smaller gap, in
agreement with the work of Jin et al. [Phys. Rev. Lett. 91, 127006 (2003)].
Since these findings rely on the same calculated gap structure, the required
consistency is fulfilled.
