|
Stefan,
yes, understood. If
you want complete invisibility though, you could actually bury the wire in the
ground, without negative effect on the magnetic field. Or cover it with fallen
leaves etc. May seem a bit odd to literally put an antenna underground
- tried it with a pair of LF receive loopsticks in the garden and it
worked quite well.
73, Markus
Sent: Wednesday, June 25, 2014 11:11 PM
Subject: Re: LF: VLF in Canada - earth loop
Hi Markus,
Right. But 8m gives a secure
distance above ground regarding the visibility of the wire. 2.5m would work as
well but then everybody can see it (easier). And some m above ground allows to
use the wire for some other games, such as a LF dipole (TX!) or a LF 3 Lambda
long wire or what ever :-)
73, Stefan
Am 24.06.2014 19:03, schrieb
Markus Vester:
Stefan,
Joe
> I
think that 8m above ground should be fine for any tests :-)
well (apart
from practical reasons like people tripping over it), you might just as well
lay the (insulated) wire on the ground.
From receive
measurements with your earlier and shorter earth antenna, we deduced a
depth of return current of 29 meters at 23.4 kHz, which
would scale to about 48 m at 8.3 kHz. Thus a two kilometer long
earth antenna would have the same radiation resistance (0.35
milliohm) as a 17 m high top-loaded vertical. But skin depth and
efficiency might be greater for very low ground conductance.
Best 73,
Markus
...
|
|
