“I have been a keen shortwave listener since 1970 and have had many receivers and antenna types during this time. Currently I have two wire antennas, a PAR Electronics EF-SWL 15 meter with impedance matching transformer, made in the US; and a home made 17 meter wire with balun. I also have a dedicated multi-stake ground or earthing system to compliment my receiver and antennas. I live in suburbia Port Macquarie, New South Wales on the east coast of Australia. Even though all our electricity wiring is under ground in our housing estate, I live in an environment where there are all types of man-made noises coming from modern electronic and electrical equipment used by my neighbours
The wire antennas I currently have are not very good at receiving weak signals in the tropical bands. However, the EF-SWL is probably the better of the two antennas for receiving less noise – the impedance matching transformer, which is earthed on one side, helps to a certain degree!
Previous Experience with Loops
Some years ago now, I read about magnetic loop antennas being very good devices for reducing man-made interference. I investigated further and actually built my own loop antenna. It was 1.4 meters in diameter using 19 mm copper tubing, and had a 25 mm gap where I placed an old fashioned dual ganged tuning capacitor similar to those used in old vintage tube radios from the 1950’s. I then coupled this large copper loop using a 1/5th size coupling loop made from 50 ohm co-ax, fed into an amplifier which in turn was fed to the receiver. I mounted this loop on top of a TV antenna rotator and used multiple cables running to the loop (apart from the 50 ohm co-ax going to the receiver) which would turn the rotator, turn the big tuning capacitor using a small geared motor and a relay which would switch in the second gang of the big tuning capacitor so I could tune down to the 120 meter band. This home made active loop antenna worked superbly for a few years and was the only way I could get to receive the tropical band stations with much reduced noise! Unfortunately, living by the coast this antenna corroded away and eventually failed! Since then, I have been searching for an alternative antenna that had less gear mounted on it and wouldn’t corrode. I tried building broadband active loop antennas but without much success!
I knew about the famous Wellbrook range of loop antennas which always had excellent reviews. But with these being made in the United Kingdom, and the difference between the Australian Dollar and English Pound, the Wellbrook loops were very expensive to purchase and have shipped out from the UK to Australia.
Anyway, I finally became frustrated enough to bite the bullet and spend my money on importing a Wellbrook ALA–1530S+P–1 active broadband loop antenna. The purchase price is £250 plus £55 freight, came to a total of £305, which converted to around $561.00 Australian dollars at the time! So, certainly not a cheap antenna, that is for sure!….READ MORE
The ARRL will sponsor a 2017 Atlantic Hurricane Season Webinar on Monday, July 17, at 8 PM ET (0000 UTC on Tuesday, July 18). The approximately 90-minute session will address the role of Amateur Radio during the 2017 Hurricane Season. Anyon... Read more