  (Abridged) We present a detailed radio study of the young supernova remnant
(SNR) G292.0+1.8 and its associated pulsar PSR J1124-5916, using the Australia
Telescope Compact Array at observing wavelengths of 20, 13 and 6 cm. We find
that the radio morphology of the source consists of three main components: a
polarized flat-spectrum central core coincident with the pulsar J1124-5916, a
surrounding circular steep-spectrum plateau with sharp outer edges and,
superimposed on the plateau, a series of radial filaments with spectra
significantly flatter than their surroundings. HI absorption argues for a lower
limit on the distance to the system of 6 kpc.
  The core clearly corresponds to radio emission from a pulsar wind nebula
powered by PSR J1124-5916, while the plateau represents the surrounding SNR
shell. The plateau's sharp outer rim delineates the SNR's forward shock, while
the thickness of the plateau region demonstrates that the forward and reverse
shocks are well-separated. Assuming a distance of 6 kpc and an age for the
source of 2500 yr, we infer an expansion velocity for the SNR of ~1200 km/s and
an ambient density ~0.9 cm^-3. We interpret the flat-spectrum radial filaments
superimposed on the steeper-spectrum plateau as Rayleigh-Taylor unstable
regions between the forward and reverse shocks of the SNR. The flat radio
spectrum seen for these features results from efficient second-order Fermi
acceleration in strongly amplified magnetic fields.
