  We present an analysis of a new Australia Telescope Compact Array (ATCA)
radio-continuum observation of supernova remnant (SNR) G1.9+0.3, which at an
age of $\sim$181$\pm$25 years is the youngest known in the Galaxy. We analysed
all available radio-continuum observations at 6-cm from the ATCA and the Very
Large Array. Using this data we estimate an expansion rate for G1.9+0.3 of
0.563%$\pm$0.078% per year between 1984 and 2009. We note that in the 1980's
G1.9+0.3 expanded somewhat slower (0.484% per year) than more recently (0.641%
per year). We estimate that the average spectral index between 20-cm and 6-cm,
across the entire SNR is $\alpha=-0.72\pm 0.26$ which is typical for younger
SNRs. At 6-cm, we detect an average of 6% fractionally polarised radio emission
with a peak of 17%$\pm$3%. The polarised emission follows the contours of the
strongest of X-ray emission. Using the new equipartition formula we estimate a
magnetic field strength of B$\approx 273\mu$G, which to date, is one of the
highest magnetic field strength found for any SNR and consistent with G1.9+0.3
being a very young remnant. This magnetic field strength implies a minimum
total energy of the synchrotron radiation of E$_{\textrm{min}} \approx$
1.8$\times$10$^{48}$ ergs.
