With zero VHF activity up until early May I decided to attempt making a magnetic loop antenna for MW-HF. The one that appeared to be most likely to work was a shielded magnetic loop. A design published by PA0FRI was the starting point and it used a standard MMIC chip which happens to be available as a ready made 30dB 0.05-2GHz (or similar variants) preamp on E-bay for under £5 (and a long wait for the slow boat from China!)
The end result was a loop of 1.2 m diameter made from 10 mm soft copper tubing with the receiving loop made of heavy duty speaker wire. A 1:1 binocular ferrite transformer connects the loop to the amplifier, which is built into a small diecast box to which the copper tubing is fixed via 1/2 inch bsp adapters.
Mounted around 2m above the ground I have received on three consecutive nights in early May Transatlantic MW signals. It works well on the short wave bands with signals on 80m/40m amateur bands for the first time in I don't know how long. It is a work in progress as it doesn't have a permanent home yet and is set to one side until the VHF Sporadic E seasons finishes. I've assembled the needed components to produce a balanced low noise pre-amp using discrete components to see if this improves performance which I will do in the autumn.
For me the main things are it costs a fraction of a commercial one such as the Wellbrook and it gives me a nice doable construction project with lots of scope for tinkering around.
What initially completely threw me was that I didn't know (or forgot) that a shielded magnetic lop antenna has the nulls at right angles to the plane of the loop. The penny having dropped - I found I was able to choose between Algeria or RTE on LW 252 kHz when the loop was suitably oriented and confirm it had good nulls.
Useful information regarding antennas for SDR products.
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