I'm not expert on it, but I suspect that two of them might somehow be related to the Transmit and Receive stations for Australia's JORN (over the horizon radar) that are located in Western Australia near Laverton.

Though if that were the case, I'd probably guess there should be more areas at the other site locations around northern Australia - so that might invalidate my guess.

https://en.wikipedia.org/wiki/Jindalee_Operational_Radar_Net...

https://www.google.com/maps/place/28%C2%B019'02.6%22S+122%C2...

https://www.google.com/maps/place/28%C2%B019'36.3%22S+122%C2...