[RFI] 160m-5mhz noise?

Dan Zimmerman N3OX n3ox at n3ox.net
Fri Nov 6 09:04:58 PST 2009

> wow, I might could afford the tropical loop antenna,
> but the $300+ unit it works on is certainly out of my price range, oh well.

ANY small magnetic loop antenna can be easily used for direction finding.

I've used this one for direction finding:


There's really nothing at all critical about anything in that project.

Wind a turn or a couple of turns of wire for the  main loop.  Measure or
estimate the inductance of that.

Calculate a capacitor that will resonate with that inductance and put a
variable cap in with a midscale
value around there.

Put some kind of coupling loop inside hooked to the radio.  For DF work the
exact impedance doesn't matter
much.    No secondary transformer is needed.  I was experimenting with
something when I drew the schematic.

A resonant magloop will have plenty of output to hear your noise on a
portable HF/MF rig.

I've even had luck with using a smaller one to increase the sensitivity of a
small AM handheld radio.  The "coupling loop" to couple energy from the big
loop to the receiver in that case is the ferrite loopstick antenna in the
portable unit.

the ferrite loopstick inside the radio.

More information about the RFI mailing list