  We have investigated the radio emission from the anomalous X-ray pulsar 1E
1547.0-5408 (PSR J1550-5418) using the Parkes telescope and the Australia
Telescope Compact Array. The flux density of the pulsar is roughly the same
between 1.4 and 45 GHz, but shows time variability. The radiation is nearly
100% linearly polarized between frequencies of 45 and 3.2 GHz, but from 2.3 to
1.4 GHz it becomes increasingly more depolarized. The rotation measure of -1860
rad/m^2 is the largest for any known pulsar, and implies an average magnetic
field strength along the line of sight of 2.7 microG. The pulse profiles are
circularly polarized at all frequencies observed, more so at lower frequencies,
at the ~15% level. The observed swing of the position angle of linear
polarization as a function of pulse phase suggests that in this neutron star
the rotation and magnetic axes are nearly aligned, and that its radio emission
is only detectable within a small solid angle. Timing measurements indicate
that the period derivative of this 2 s pulsar has increased by nearly 40% in a
6-month period. The flat spectrum and variability in flux density and pulse
profiles are reminiscent of the properties of XTE J1810-197, the only other
known radio-emitting magnetar, and are anomalous by comparison with those of
ordinary radio pulsars.
