After a century on the AM band, ABC Radio stations in Perth will move to FM in 2026
Almost 102 years after ABC radio first hit the airwaves, Perth listeners will experience a major improvement in sound quality when the network’s three AM stations move to FM in 2026.
The long-awaited change follows a decision by the Australian Communications and Media Authority (ACMA) to change plans for the Perth and Far Western Australia radio license area.
ABC chief executive Hugh Marks said this was an exciting opportunity to improve the quality of services offered to Perth viewers.
“We have long been aware of the challenges of AM recruitment in Perth. Thanks to FM, viewers can enjoy richer sound and more reliable broadcasts, keeping them connected to the programs they love.“
ABC audio director Ben Latimer said the switch to FM would not only significantly improve sound quality but also lead to significant savings.
“These new FM licenses will deliver better quality sound and be significantly cheaper, offering better value to taxpayers as AM demand declines in capital cities,” Mr Latimer said.
“This change reinforces the ABC’s commitment to our radio services and our ongoing desire to deliver the highest quality broadcasting to audiences across the country.”
The transition date and new frequencies for ABC Radio Perth, Radio National and News Radio will be announced in the new year.
Why is AM reception an issue in Perth?
The answer is how amplitude modulation (AM) frequencies are transmitted and Perth’s sandy soil, which is the bane of all Perth gardeners.
While we say radio is on the airwaves, AM transmission relies on ground waves.
“AM operates from what are called sites, and each site is located somewhere where there is good propagation of the signal and where the signal will be best transmitted,” said Gavin Bowman, ABC’s director of transmission contracts.
“AM moves better over the ground and so you need a course with good ground dispersion properties.
“AM really likes moist, wet soil to go further, and most of the time you’ll have an AM tower in a swamp or next to a river or somewhere like that, where the ground is wet.“
AM transmitters rely on good ground conductivity to carry signals across the ground. In areas like Perth, dry, sandy soil and electrical infrastructure weaken signals over distance. (ABC Transmission)
Perth is located on the Swan coastal plain, famous for its dry, sandy soil and lack of rain for months.
AM needs a paddock in the city
Since 1939, the ABC Radio Perth AM transmitter has been located at Hamersley in Perth’s northern suburbs, a large bushland reserve with an exclusion zone around the 180-metre-high mast.
Unlike FM, which needs a tower or mast for overhead line-of-sight propagation, AM requires much more land.
“The reason is that [with AM] The mast you can see in the middle of the field is just a small part of the overall infrastructure that transmits the signal,” Mr Bowman said.
“One of the main parts is that they run extra wires to ground, which makes the transmitter electrically longer.
“You have radial cables coming out of the pole and routing the signal across the ground much more efficiently than a pole could do on its own.
“Because of that requirement, you have to have a really big block of land—we’re talking acres and acres and acres.”
FM transmitters are mounted high on ridges or towers. They use line-of-sight propagation to provide wider, clearer coverage with less power and less dependence on ground conditions, making them ideal for high-quality audio in dense metropolitan areas. (ABC Transmission)
Not only does AM consume a lot of space in capital cities, an AM mast can only offer one or two services, so each radio station needs its own paddock.
“In the case of FM and TV, they can all share the same infrastructure, so a single site on top of a hill can host a multitude of services.”
he said.
“There’s a huge sharing capacity where you can cover those costs across multiple services that you can’t do in AM.”
Highway drives a train through car listening
As if sand and land weren’t enough, the expansion of Perth’s rail network north and south along the middle of the Mitchell and Kwinana highways in the 1990s created another headache for AM radio listeners.
A Transperth train on the Joondalup line. Electrified lines made it difficult to listen to AM radio in the car on the highway. (ABC News: Eliza Laschon)
Electrified train lines cause interference that makes listening to AM radio in the car while driving on the highway nearly impossible.
“Every time a train passes and you tune your AM radio, that has a significant impact on your quality of service,” Mr. Bowman said.
For many commuters, the intervention led to permanent shutdowns of AM stations while on the highway.
101 years on the AM band
It’s the end of an era for ABC Radio Perth (first called 6WF, later 720), which began broadcasting more than a century ago on June 4, 1924.
It was not established by the ABC, but was a commercial station run by the Westralian Farmers Co-operative (now Wesfarmers) with the aim of reducing the isolation of people in the bush.
According to Wesfarmers’ official history, the station came into being when John Thomson, head of the company’s wheat department, was traveling on a difficult dirt road in the wheat belt on his way to Bruce Rock when two of his car tires burst and he had to wait four hours for a passerby to come and help.
During these four lonely hours, he thought about the isolation experienced by people in the country and decided on wireless telegraphy. [radio]It was an excellent solution that had just emerged in Australia.
Running a radio station was far from the organisation’s usual business, but Mr Thomson managed to persuade management that Wesfarmers should bid for the first radio license in Perth.
The station was named 6WF after Wesfarmers. Four years later, tired of running a radio station, Wesfarmers sold 6WF to the Commonwealth government, which eventually became part of the ABC local radio network.
Mr Latimer confirmed the switch to FM in Perth would have no impact on the ABC’s regional radio services or the ABC’s emergency broadcasting commitment.
“ABC is in the fortunate position of having high-power AM transmitters available in areas adjacent to Perth to provide emergency broadcasting to all areas outside the metropolitan area currently covered by the Perth AM signal,” he said.
