From the 1st Jan 2015, it will be illegal to use wireless microphones in the 694 - 820MHz band in Australia.
This is because the Australian Government is making some fast cash to sell off bandwidth to mobile phone companies (called the Digital Dividend). To do this, they will be pushing everyone else out of these ranges to do so.
So on 1st Jan 2015, date wireless systems are supposed to use the 520MHz - 694MHz band - but at the same time avoid the local TV station frequencies which are also in this band.
Wireless transmitters are also allowed to use the 1790-1800MHz band.
Suggested wireless frequencies for wireless systems around Perth are as follows:
More info...
ACMA Press Release: http://www.acma.gov.au/theACMA/Newsroom/Newsroom/Media-releases/new-arrangements-for-wireless-microphones
ACMA Info Page: http://www.acma.gov.au/Industry/Spectrum/Digital-Dividend-700MHz-and-25Gz-Auction/Reallocation/wireless-microphones-1
Frequency Finder: http://ddready.com.au/