  The effects of introducing a harmonic spatial inhomogeneity into the
Kalb-Ramond field, interacting with the Maxwell field according to a
`string-inspired' proposal made in earlier work are investigated. We examine in
particular the effects on the polarization of synchrotron radiation from
cosmologically distant (i.e. of redshift greater than 2) galaxies, as well as
the relation between the electric and magnetic components of the radiation
field. The rotation of the polarization plane of linearly polarized radiation
is seen to acquire an additional contribution proportional to the square of the
frequency of the dual Kalb-Ramond axion wave, assuming that it is far smaller
compared to the frequency of the radiation field.
