Новости LF/VLF/ULF/SLF/ELF > VLF (ОНЧ — очень низкие частоты) диапазон с частотами от 3 до 30 кГц
VLF: New DK7FC experiments on 17.47 kHz - Антенна из дорожного отбойника
rw3adb:
Сию дискуссию, считаю полезной оставить у нас тут.
Hi Jim,
(I changed the subject.)
Well, i remember there was a day where Markus transmitted on 8270 Hz, and me too. We were both visible on Paul's grabber.
Markus told me i was about 5 dB stronger there. Here is a spectrum from Pauls grabber (me on 8270.000 Hz) http://78.46.38.217/fbins3.html#p=1532887200&b=120&s=pw&m=cardioid&w=r&h=42&z1=0.34&z2=0.64&c=1&mb=632,136,655,212,1
Well the Distance from Paul to Markus is 1028 km, the distance to my ground loop is 840 km. Markus used an E field antenne, i used a H field antenna, so there may be some better filter and antenna mixing coefficients for one of the stations. Let's say, due to the different distances, i have an advantage of 1.8 dB.
Markus states he emits 10 uW (i guess that is EMRP) so my signal seems to have about 20 uW EMRP during that transmission, in which i run 550 mA antenna current.
Meanwhile i can run 1.8 A antenna current (+10.3 dB), so the signal could have 215 uW. That is with 255 W RF power. So the antenna efficiency is about -60 dB at 8270 Hz, based on Markus' 10 uW statement (?).
I have no idea if the equivalent loop area actually increases with a dropping TX frequency. On LF it seems to do at least :-)
Assuming the area is constant, the efficiency will be even 14.4 dB lower on 1570 Hz and 18.6 dB lower on 970 Hz. Uuuh i hope this is not true :-)
So the EMRP on 1570 Hz was maybe 8 uW at a -74.4 dB efficiency.
73, Stefan
Am 10.09.2018 08:19,
Свернуть
Hello Markus, Stefan, Paul,
Is there any way of guessing the ERP of the 1570 Hz (or 2970 Hz) earth-loop tests last week?
I noticed that ERP/wallplug-power efficiency of the Norway (Dazey) test at 1280 Hz might extrapolate to about 2E-8 with 1 km between electrodes (with ~ 20 ohm electrode-to-earth resistance); and though it might be informative to compare.
73,
Jim AA5BW
rw3adb:
Hi Jim,
You can still find the single decodes in the WSPR database. Most of the reports were with the wire in loop configuration (ends grounded). This gave clearly better results! I switched to the dipole config yesterday 09.SEP. 17:38 UTC
Yes, 10 W RF out, at least in the loop config.
73, Stefan
Am 10.09.2018 16:35,
Свернуть
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
rw3adb:
передатчик Стефана участвовавший в сей серии экспериметов.
оформил ссылочкой - там оч большая картинка. открывайте в отдельную вкладку.
rw3adb:
-перенесено
rw3adb:
-перенесено
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