While looking at pictures of vintage tube radios on evilbay, I noticed that most every tube set made in the post WW2 era used external wire antennas, In the USA, most all sets of the same era used internal loop or loopstick antennas. Consumers liked not having extra wires inside the home. So I'm puzzled as to why Australian radio manufacturers didn't use loops or loopstick antennas. Maybe a patent licensing issue?

Anyway, it's easy to make your own loop antenna. It connects across the antenna section of the radio's tuning cap: Remove the old coil that coupled the ariel to the tuning cap.

I just made an antenna for a radio I installed into an old bookshelf speaker (not a good one, so don't worry). I made it large to capture more signal out of the air. What to do: Get a spool of wire about a hundred feet long. Select wire without solder coating on it. Skin effect would force most of the RF current through the solder, which has a higher resistance than copper, and that will kill the Q. Better yet if you have a supply of silver coated wire, usually done with Teflon wire (Teflon does bad things to copper, so the silver plating). Silver is a better conductor than copper, but as silver is much more expensive, everyone uses copper to wire their houses. Or use litz wire for the antenna if you happen to have some. Anyway, get some corrugated cardboard from that box your latest ebay win came in, and make a coil form. Cut an odd number of notches one every 3 cm (centimeters) or so. You will wind the wire in a basket weave pattern. This basket wave pattern needs the odd number of notches or else it won't work out. That reduces stray interwinding capacitance. You have seen this done in older AA5 antennas. I made one about 40 cm by 25 cm. It took about 17 turns. But be prepared to add or remove turns or fractions thereof. Smaller size loops will need more turns. Tune the radio the antenna is for to a weak station near the bottom of the band, like 558kHz. Connect the inner wire of your antenna to the "hot" part of the antenna tuning cap, and the outer wire to the AVC "RF ground". Use a high impedance voltmeter to monitor the AVC voltage. Add or remove turns of wire from your antenna to peak the signal strength of that station selected above. A few solder joints in the antenna won't hurt anything as long as you can't get shorted turns. You can have a meter or so of wire between the antenna and AVC line as you're tweaking the antenna. You are actually adjusting the antenna inductance to resonate it to the tuning cap. After you get the peak, tune up to a station around 1500kHz and tweak the antenna trimmer cap. If you did the basket weave pattern, you should be able to get a peak. The radio should be more sensitive now. Check that strong stations are not distorted or causing intermod in the band. Now you're done.

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There were some Australian sets with internal aerials. Portables used them of course; I have an Astor battery portable from the late 40s with a flat loop aerial in the lid.

I am not sure if I am technically correct though I do believe that aerial antennas simply worked better than inbuilt coil antennas.

Mainland Australia is similar in land area to mainland United States however because the Australian population is much much smaller there was little need for a large number of radio stations. When licenced broadcasting began in 1923 through 1924 there were only a handful of stations and all of these were in the state capitals. Even the national capital, Canberra, didn't have its own radio station at the time. From memory the stations were 2BL, 2FC, 3AR, 3LO, 5CL, 6WF and 7ZL. There was no station in Queensland that I know of until 4QG was added when the Australian Broadcasting Commission was founded and took over all the above stations.

Because this was pretty much it every radio had to be capable of long-range reception, especially since the transmitters were only a few hundred watts to start with. None of the above stations were networked - each broadcast its own programme schedule. So there was in effect a choice of programming provided your valves were in good nick and your receiver had a good aerial and earth wire.

Even when new commercial stations such as 2UE, 2UW and 3DB came along these stations were still in state capital cities and there was a bit of a wait before radio came to rural areas. So right up until the 1950s most radios were still being sold without an internal antenna fitted. As many people already had aerial antennas strung around the picture railings of their lounge room the market didn't demand a move to internal antennas although there were exceptions to the rule, as pointed out by Sue.

By the time there were dozens of radio stations in each state there was pretty much little or no need for either an aerial or internal antenna. Most of the working receivers I own will pick up all Sydney AM stations without an antenna of any kind fitted. The 1960's saw the big change, with the plastic receivers of the era being fitted with ferrite rods and coils. Then when transistors and FM broadcasting came into the picture the requirement for an external antenna once again became commonplace, even if only for a short time as one of FM's technical limitations is that the signal simply doesn't go very far despite some of the transmitters pumping out 50kW of signal, yet with the number of FM stations around, finding one to listen to isn't a problem in most localities.

On a five valve radiogram I used to use when I lived in the New England/North West region of New South Wales I could regularly pick up both Sydney (420km), Melbourne (1,300km) and Brisbane (680km) stations with an aerial about 5 metres long. In this day and age of copious radio interference and using a beast that was about 35 years old at the time that is a pretty good effort.

One other issue is probably one of cost. A ferrite rod is a fairly inexpensive item though most Australian receivers were built to a price and if quality was to be maintained in the manufacturing process then cutbacks on features would be necessary.

So it sounds like the combination of few people and cities, and large regions of empty land, makes a need for long distance reception. Few cities makes for less man-made noise, which makes for better signal to noise ratio. There's natural noise, but low man made noise helps a lot. And to keep the cost of the radio down, use the long wire antenna to pick up enough weak signal to overcome receiver noise.

Back in April 1986 I holidayed in Australia, and had an AM/FM portable radio/tape recorder with me. At Ayer's Rock during the day, the radio dial AM and FM was completely dead, not radio stations at all. Of course, at night the dial filled up with skywave propagation on AM.

I taped a number of Australian radio stations during my trip then, Cains, Alice Springs, ayers Rock, Melbourne and Sydney to create "air checks" for my friends in the American radio broadcast industry. If anyone is interested in such, PM me so I can email the mp3s of these.

Back then you'd be lucky to have got some petrol or a beer out in the 'red centre' of the Northern Territory. I regret that I haven't toured the area myself yet and as a keen photographer I am keen on going at some stage when work commitments permit.

In 1986 there were only a handful of FM stations - a similar situation to the AM band in the 1920's. FM really only took off after the Commonwealth Government started allowing AM stations to convert in the early 1990's.

I lived in rural New South Wales for several years about 20 years ago. It's hard to imagine in this day and age of around 100 TV channels and dozens of radio networks in most populated areas and satellite services for remote areas than only back that far the best a rural dweller could hope for was two TV channels (a local station + ABC) and two AM radio stations, again a local station and ABC Radio) yet at the time most people seemed content with it.

Here's the current situation with electronic media in Alice Springs at the moment. If you can remember the station callsigns you homed in on when you were here there is a chance that you can listen to the programme stream on their websites. Most of the networks have these now.

Interesting idea to cut a loop antenna in place of the aerial coil. have had a hankering to do the same thing with a PLL radio tuned with varicaps, but haven't been desperate enough in terms of reception to try it.
Does any one know if this idea is possible and if so is it practical?
I envisage a loop fitted with a plug arrangement that interrupts the ferrite rod coils ie can be used as needed.
Any comments?

What about using a ferrite rod with a coil wound on in place of the loop?

Yes I suppose a nice long ferrite rod from an old ghetto blaster might do. The present rod is only about 4.5 - 5inch and 7mm dia.
My doubt though is - could this be effectively tuned by the varicaps and would the longer lead in present difficulties with tuning range, and sharpness of tuning?