ULF: ERP and loop efficiency

[DK7FC <selberdenken@posteo.de>]

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, schrieb hvanesce@comcast.net:

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