N 63A: a supernova remnant within an H II region

N 63A is a bright supernova remnant embedded in a large H II region in the Large Magellanic Cloud. We present the first detailed radio map of such an object using data from the Australia Telescope. The remnant shows a shell structure but of unusual thickness. The measured polarization of the brightest clumps on the shell is very low, probably because of internal Faraday rotation