Rik Strobbe schrieb:
Dear LF group,
I have been looking for some information about the polarization of small
loops, but no success.
For full-size loops things are quite clear, a loop can be polarized
horizontal or vertical depending on the feeding point.
What about small loops ?
I found several descriptions of small transmitting loops close to ground
and there loops were fed at different places (center horizontal side, at
the edges). Polarization seems to be vertical in all cases.
And what about a small loop is free space ? Current distribution is uniform
over the entire loop, regardless of the feeding point. So one would expect
always the same polarization (but which one ?). Unless also the voltage
distribution plays a role.
Anyone who can point me to the right theory and/or has experience with
feeding small loops at different points ?
Thanks in advance,
Rik ON7YD
Hi Rik es all,
the following may confuse the loop scene still more:
I have a loop 70m long, 12m high and 2m above ground with two windings,
fed at the lower E (east) edge.
some weeks ago I made a field strength test L-aerial (17m mast and 340m
longwire 17m to 9m up) contra loop.
Geri/DK8KW measured the strength using his MV62.
the loop is erected N/E. DK8KW is located S from here.
result: no difference btwn the aerials as Geri reported (both 20uV/m).
so can one say the (my) loop polarizes vertical (non directional)
if used as TX-aerial?
vv. used as RX-antennas loop to L-antenna was -63dBu to -50dBu (indicated by a
RYCOM-rx) receiving DK8KW.
receiving Reino/OH1TN (nearly E) RYCOM indicates no
difference btwn the two antennas.
but Reino does not hear me if I do use the loop as TX-aerial.
with the L-aerial conn to the TX Reino gives me regular RST 569.
in abt three weeks I will go to the bottom of it.
I will perform tests in QRSS mode during
afternoons on 136.0kHz for the purpose of field strength measurements.
distance to the aerials: on average seven km (3xlambda).
transmitter power output will be 20 Watt, 130 Watt and 800 Watt.
Aerials: inv. L-aerial and TX-LOOP.
the test will last several weeks. I cant make any schedule.
is the qrg ok? any protests from the bandplaners?
btw. Rik, in ur fine prgr QRS I do miss the possibility keying a
continuous dash among the text.
regards
dj8wx/Uwe
regards
Uwe/dj8wx
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