Loop Antennas.

[Dave757]

I have just acquired a set of three loop antennas with a
control box which enables coverage of the entire spectrum
from 140kHz to 30MHz in 8 bands. It is a totally passive device

It is Polish in origin, dating I think from 1981, and manufactured
by Inco. The model is Zespol Anten Typ. AMZ-3A/50.

It's so heavily built, I'm wondering what application it was designed
for. Does anyone have any details or service info, - a circuit would be
very useful .

Kind regards

Dave

[Andrew2]

I wonder if they were meant to be used seperately on three vehicles for direction finding? Three bearings taken from widely-spaced points would quickly locate a source of transmission.
If they were meant to be used together at the same site, I can't think.

[Dave757]

Hi Andy,

The loops are a set of three different sizes, the largest covering
from 140 - 500kHz, the middle one from 500kHz to 4 MHz, and the
smallest from 4 MHz to 30 MHz. The frequencies are selected using
8 bands on a slow motion tuning dial, - the bottom 2 bands are for the
largest loop, and the other 2 loops have 3 bands each. Each band has
a loading coil set into a substantial turret, and there is a similar
arrangement for the sense antenna (which I do not have but likely to
be a whip).
So it is a single installation, and obviously intended for internal use,
as although it is very heavily built, it would not be weatherproof.

Kind regards

Dave

[Andrew2]

Ah, so the three loops are to cover the full spectrum, each one covering a 'waveband'. Of course I should have realised. Somewhere I've got a BBC (or maybe RA/Ofcom) document about the development of a new loop system. They ended up with two loops, each tuned by fixed capacitors and relays, with fine tuning by varicap diodes.

[Chris Wilson]

I have acquired a set of these today, also without the whip. Possibly yours even? Did you ever find out anything more about them please? I am told they were used by our PO for field strength measurements? But also told they came from Rugby TX station.

[kalee20]

May be for industrial use, with a calibrated receiver for measuring RFI emission levels from equipment.

RFI measurements necessarily have to cover a wide frequency range (right up to GHz these days) so lots of different loops would be necessary.

[Chris Wilson]

This is a similar kit, found a link to these using Google:

http://translate.google.co.uk/transl...channel%3Dfflb

[WaveyDipole]

The two Polish references I encountered on Google discuss using such an antenna to measure EMF and RFI from equipment. In one case specific application was being made in the medical field to measure interference from medical equipment.

[majoconz]

Looks interesting. How much is 400,00 zlotys?

[Chris Wilson]

£75 Sterling or 152 NZ Dollars. I paid less than half of that for these though.