Greetings Nas2768:
Here are the Australian
over-the-air broadcast channel frequencies:
https://www.scanaustralia.bigpondhosting.com/broad/autv3.html
Here are the U.S. over-the-air broadcast channel
frequencies:
https://www.csgnetwork.com/tvfreqtable.html
As you will see, the frequencies do not coincide
with each other, and neither do the bandwidths (6
MHz for U.S. vs. 7 MHz for Aussie). So, if it is
a U.S. converter, that would explain the incompatibility.
Over-the-air signals are picked up by placing
a special VHF/UHF antenna on the satellite dish,
and then either couple into the satellite cable
or are routed in a separate coax to the indoor receiver.
If you do not have that extra antenna, then you
cannot get the over-the-air channels.