[Robert-UK]

Paul -

I can confirm there was nothing about external loop aerials published in the PW "Take 20" column.

However, in addition to the Radio Bygones article (which is indeed what you want) you might check the following:

Everyday Practical Electronics, September 2000
Practical Wireless November 1966 (MW loop)
Practical Wireless April 1973 (MW loop plus transistor amplifier)
Practical Wireless November 1979 (MW/LW loop aerials)

However, all the PW offerings are frame aerials, not ferrite rods.

Regards

Robert