Reversal of the sense of polarisation in solar and stellar radio flares

It is shown that numerical integration of the equation of polarisation transfer for generalised Faraday rotation provides an alternative to mode-coupling theory for treating propagation through a quasi-transverse (QT) region. At a QT region, where the sign of the component of the magnetic field along the ray path reverses, the sense of circular polarisation reverses below a frequency omega_t, and is unchanged above omega_t. There is along-standing difficulty in the interpretation of the polarisation of radio emission from bipolar regions on the Sun: observational and theoretical estimates of omega_t appear inconsistent. The alternative approach may help resolve this difficulty.