[Lowfer] Loop on ground antenna for VLF

[John Bruce McCreath]

Hi Guys…..just wanted to share with you the results of experiments I’ve been
doing over the last few weeks.  We’ve all read about how good the LoG is on
the lower HF bands for receiving, but I noticed that it hadn’t been tried out on
either LF or VLF, so I thought I’d give it a go.

I started with a single-turn loop of #10 copper wire ten feet in diameter, inside
a plastic pipe just laying on the ground.  I tried several methods of matching
it to the feed line, including transformers I wound on toroid cores.  They did
work, but not nearly as well as an audio transformer did.

Those results indicated that it worked in principle, but I knew that I could do
better, so I decided to go with a multi-turn loop, of a larger diameter.  A local
hardware store had a 50 foot outdoor extension cord on sale, so I bought
one, cut off the connectors and connected the three wires in series.

I used a Hammond 119DA transformer for matching.  The loop connects to
the 4 ohm side and the 600 ohm winding connects to a CAT5 cable with the
wires paralleled to give me a balanced feeder to the shack.  I wound a 22
turn common mode choke indoors on an old flyback transformer core.

The antenna connects via an XLR plug to the mic input of my UMC202HD
USB audio interface to make use of its Midas preamp.  I’m running Spec
Lab in a Win10 PC, configured as a VLF receiver with its plotter window
activated as my SID detector.

Does that antenna work?  You bet it does!  It’s every bit as good as my old
Loop in Tree antenna, a shielded, 25 turn, 1 meter square vertical loop that
hangs in a tree outside the shack window, about six feet off the ground.
The new LoG and feeder is completely invisible laying on the lawn.

73, J.B., VE3EAR

LowFER Beacon "EAR"
188.831 kHz. QRSS30
EN93dr

PS - I hope to have EAR’s antenna fixed soon.  I found a guy that climbs!