Hi Tony,
This is very fine! Probably you monitored DHO38 @ 23,4 kHz (TX in
nothern Germany). So it is once again confirmed that the antenna behaves
rather like a loop antenna. Additionaly the signal drop when
disconnecting the far electrode (opening the loop) confirms that it is
rather working as a H field antenna than a E field antenna. This agrees
very much with my own experiments i did some weeks ago.
I wrote my report here and in a published pdf but currently i don't know
the link ;-)
It would be very interesting if you would try to receive my signal in my
next VLF experiment with that earth antenna!!!! ;-) The E/W antenna
should be best. In some weeks i will transmit again on 8970 Hz :-)
Best 73, Stefan/DK7FC
Am 17.08.2010 17:11, schrieb Tony:
Hi Stefan
I tried the antennae this afternoon on 23 KHz and the E/W wire is 12dB
up on the N/S wire.
I have no idea what I was receiving as I was using a FRG-7700 which
only displays to the nearest KHz.
When I disconnected the far end from the earth stake the signal
dropped by 18dB, the receiver is at the eastern end of the E/W wire
and the northern end of the N/S wire.
I will try sub 10 KHz when I sort out where my local QRM is coming from.
Tony, EI8JK.
On 16/08/2010 22:16, Stefan Schäfer wrote:
Hello Tony,
Thanks for that interesting work!
Could you extend the measurements to the VLF band? It would be
interesting what the levels and directivity would be there.
73 and pse a sked for your upcoming LF stn! :-)
Stefan/DK7FC
Am 16.08.2010 16:35, schrieb Tony:
Yesterday I spent some time playing with different antennae.
I started by laying out another wire 52m long orientated roughly
north/south and then I shortened my original wire also to be 52m and
this one is east/west, both terminated with an earth rod.
Results were not as expected however as although the two earth
electrode antennae show most definite directivity they were the
wrong direction.
I monitored BBC R. Bristol on 1548 KHz which is about 500 Km due
east of me and on the inverted L (tuned VSWR 1.6:1) I could just
detect a carrier heterodyne, on the N/S earth electrode antenna it
was S1 but on the E/W earth electrode antenna it was S3.
RNE5 on 531 KHz about 960 Km due south of me was S3 on the E/W and
S8 on the N/S
HGA22 (135 KHz) to my east was S4 on the E/W and S1 on N/S
Readings were taken about 12:00 utc so most definitely ground wave.
I was expecting the directivity to be broadside on the earth
electrode antennae, but they seem to behave like a Beverage in that
respect, but something that I think I will investigate further,
maybe see if there is any difference if I terminate them with a
resistor.
I'm sure Mal is correct though that they would be useless to TX
through but for RX they seem to have possibilities especially after
dark as they are a lot quieter.
All good fun.
73, Tony, EI8JK.
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