  Angle-frequency coupling in scattering of polarized light on atoms is
represented by the angle-dependent (AD) partial frequency redistribution (PRD)
matrices. There are several lines in the linearly polarized solar spectrum, for
which PRD combined with quantum interference between hyperfine structure states
play a significant role. Here we present the solution of the polarized line
transfer equation including the AD-PRD matrix for scattering on a two-level
atom with hyperfine structure splitting (HFS) and an unpolarized lower level.
We account for the effects of arbitrary magnetic fields (including the
incomplete Paschen-Back effect regime) and elastic collisions. For exploratory
purposes we consider a self-emitting isothermal planar atmosphere and use
atomic parameters that represent an isolated Na\,{\sc i} D$_2$ line. For this
case we show that the AD-PRD effects are significant for field strengths below
about 30G, but that the computationally much less demanding approximation of
angle-averaged (AA) PRD may be used for stronger fields.
