By Jock Elliott, KB2GOM
It was this post by Alan — https://swling.com/blog/2024/11/bbc-rd-how-to-test-a-loop-antenna/ — that set me off. After downloading the BBC report on how to test a loop antenna, I noticed the following in it:
“Polarisation Illustrations of the antenna usually show it mounted upright; that is, with
its axis parallel to the ground. This is fine for the reception of LF and MF transmissions, which
are vertically polarised, but most HF transmissions are horizontally polarised.”
Huh, I thought, “I wonder this would have any bearing on how I use my MFJ 1886 loop antenna?
So hooking the 1886 loop to an SDRplay RSPdx, here’s what the spectrum looks like on medium wave in vertical orientation with the 1886’s internal amp turned on:
And here’s what the medium wave spectrum looks like with the loop in horizontal orientation, amp on:
But what about shortwave reception? Here’s 31 meters in vertical orientation:
And here’s 31 meters with the loop in horizontal orientation:
Here’s 25 meters in vertical orientation:
Here’s 25 meters in horizontal orientation:
It looks to me, at the very least, the noise floor is lower . . . or I am in desperate need of a laxative?
For more about my adventures with the 1886 loop, check this — https://swling.com/blog/2022/10/testing-the-mfj-1886-receive-loop-antenna/ — and this — https://swling.com/blog/2023/01/saturday-morning-fun-fat-mw-dxing-with-the-mfj-1886/
My conclusions: I definitely don’t want the 1886 loop in horizontal orientation for medium wave DXing, but I think that the flat orientation might help for shortwave DXing.
What do you think?
