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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