The Flying Doctors - Season 4 Episode 6 Broken Airwaves

Kate thinks everybody takes her for granted and expects her to do things for them. She takes a holiday to go to Thargoomindah and watch the rodeo, and she brings her horse Toby. After a while her car gets overheated, so she stops and takes Toby for a ride. Something scares him, and Kate is thrown off and hits her head. When she wakes up she can't remember anything. She finds a deserted shed, and manages to get in contact with DJ at the base, but she doesn't know where she are. DJ gets her to transmit and every property avaliable to listen in, to try to determine where the signal is strongest. Finally they figure out where she is and can rescue her!