Hello
Stefan,
Excellent
results, and fascinating.
For
the 13 WSPR reports below, is the antenna in dipole-on-ground mode
(ends not grounded) or in earth-loop mode (ends grounded)?
Was
the 10W that you mentioned the power-amplifier output power?
73,
Jim
AA5BW
Hi LF,
The experiment is finished. Batteries are back charging.
These are the best reports:
|
Timestamp
|
Call
|
MHz
|
SNR
|
Drift
|
Grid
|
Pwr
|
Reporter
|
RGrid
|
km
|
az
|
|
2018-09-09
03:30
|
DK7FC
|
0.137425
|
-27
|
0
|
JN39
|
1
|
SM3LNM
|
JP82qg
|
1559
|
20
|
|
2018-09-09
10:30
|
DK7FC
|
0.137425
|
-24
|
0
|
JN39
|
1
|
2E0ILY
|
IO82qv
|
767
|
303
|
|
2018-09-09
04:10
|
DK7FC
|
0.137425
|
-25
|
0
|
JN39
|
1
|
G3XDV
|
IO91vt
|
568
|
300
|
|
2018-09-08
12:20
|
DK7FC
|
0.137424
|
-16
|
0
|
JN39
|
1
|
DL4RAJ
|
JN68kj
|
449
|
103
|
|
2018-09-09
10:20
|
DK7FC
|
0.137425
|
-7
|
0
|
JN39
|
1
|
DL0AO
|
JN59vk
|
349
|
89
|
|
2018-09-09
01:20
|
DK7FC
|
0.137426
|
-24
|
0
|
JN39
|
1
|
PA0RDT
|
JO11tm
|
327
|
315
|
|
2018-09-09
16:30
|
DK7FC
|
0.137425
|
-21
|
0
|
JN39
|
1
|
PI4THT
|
JO32kf
|
306
|
359
|
|
2018-09-09
07:30
|
DK7FC
|
0.137425
|
-6
|
0
|
JN39
|
1
|
DF6NM
|
JN59nj
|
301
|
90
|
|
2018-09-09
01:40
|
DK7FC
|
0.137429
|
-14
|
0
|
JN39
|
1
|
DC0DX/RF
|
JO31lk
|
218
|
0
|
|
2018-09-08
21:50
|
DK7FC
|
0.137424
|
-28
|
0
|
JN39
|
1
|
DC5AL-R
|
JO31lk
|
218
|
0
|
|
2018-09-09
00:50
|
DK7FC
|
0.137425
|
-27
|
0
|
JN39
|
1
|
DF2JP
|
JO31hh
|
205
|
354
|
|
2018-09-09
07:50
|
DK7FC
|
0.137425
|
+1
|
0
|
JN39
|
1
|
DK7FC/HD
|
JN49ik
|
127
|
91
|
|
2018-09-09
09:50
|
DK7FC
|
0.137425
|
0
|
0
|
JN39
|
1
|
DL1GCD/1
|
JN48ar
|
115
|
136
|
It was interesting to see the special characteristic for such an
unconventional antenna. Another interesting thing was to learn about
the different feed point impedances. I had no idea before...
Markus calculated 0.4 % efficiency for daytime in low distances, which
is not bad at all. The actual distance to Markus is 230 km and with
just 10 W it is possible to have a normal CW QSO!
But the night characteristics are not really favourable :-)
It would have been interesting to have someone receiving with a loop
antenna, which could pick up the high angle radiation much better than
an E field antenna, eventually.
There is so much to play with. It never ends :-)
73, Stefan
Am 10.09.2018 07:06, schrieb [email protected]:
Hello
Markus and Stefan,
Markus
mentioned:
“high
angle radiation …possibly leading to deeper fading at intermediate
ranges”
I would
guess the same.
I checked
the following to see if the 900m/137kHz configuration (> 1/4
wavelength freespace, >> 1/4 wavelength in earth), or some
particular earth conductivity, or very-close-proximity to ground, or
perhaps some hemispherical spreading in earth ground currents might
reliably mitigate high-radiation-angle fading at intermediate ranges.
a) https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2005RS003298
b)
https://nvlpubs.nist.gov/nistpubs/jres/64D/jresv64Dn1p27_A1b.pdf
c)
“Characteristics of a Power Line Used as a VLF Antenna” (Dazey, Radio
Science 1982)
Items (a,
b and c) augmented a perspective that experiments are more reliable
than theory in this realm.
I couldn’t
find any basis in theory for ruling out high-radiation-angle fading at
intermediate ranges, even with 900m/137kHz, and earth-loop and
dipole-on-earth configurations, especially given some possibility of
Eh+Ev nulls.
Perhaps
more valuable than much of the theory is that the transmitter provided
good far-field signals on first attempts at 1570 Hz, 1970 Hz, 2470 Hz,
2970 Hz and 137 kHz. That’s really something to think about.
73,
Jim AA5BW
From: [email protected]
[mailto:[email protected]]
On Behalf Of Markus Vester
Sent: Saturday, September 8, 2018 5:53 PM
To: [email protected]
Subject: Re: LF: Re: 137 kHz WSPR-2 on a 900m long ground
loop, this weekend
Hi Stefan,
indeed your signal has been very consistent around 5 uV/m and -8 to -10
dB in the afternoon. At 230 km range, this would indicate a radiated
power around 40 mW (EMRP), or 0.4% antenna efficiency. Around
nightfall, heavy QSB set in, with occaional minima where the signal
fell below the decode threshold but was still ghastly visible in the
waterfall with heavy RDF colour aberrations. I suspect that the
diplole emits more high angle radiation than a
vertical, possibly leading to deeper fading at intermediate ranges.
Best 73,
Markus (DF6NM)
-----Ursprüngliche Mitteilung-----
Von: DK7FC <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Sa, 8. Sept 2018 22:45
Betreff: Re: LF: Re: 137 kHz WSPR-2 on a 900m long ground loop, this
weekend
Thanks to
the many stations beeing RX-active on LF WSPR tonite.
It is very strange, the SNR reported by the stations below 500 km
distance was very good in daytime but now at night there are not more
stations receiving me, except 2 reports by 2E0ILY.
Also the software just reports JN39 instead of JN39WI.
Maybe some reports are not uploaded or shown on the database, because
of
conflicting locators for the same callsign?
I can hardly imagine that nothing comes through at night. Very odd.
Does someone have an explanation what can cause these good results
during the day and such bad results at night?
73, Stefan
PS: My QRG is 137.425 kHz and starts each xx:x0 (each 10 minutes).
Maybe
someone can see somethning on the waterfall display?
...
