28 Feb 2014

Top Band on the 15m baseline earth-electrode "antenna"

Running the 2W  from the PA (ERP not known but mWs likely) I received 12 unique spots overnight of my 160m WSPR signal with best DX report from SM6WZI  (JO67mp) at 1007km, not at all bad going. At my end, I copied just 6 unique stations including SM6WZI as my best DX spot. My reports (of others) are not as good as their spots of me, suggesting my noise floor is higher than theirs?

At this point I am running out of WSPR "experiments" that I can do with the antennas already in place. You may recall my stroke is preventing ladder and antenna work outside presently. I could give 137kHz a go but will need a preamp building first. "Down the road" at the old QTH G8HUH was regularly able to copy me on 137kHz WSPR QRP to my 20m earth-electrode"antenna" at 250km. Main issue on 137kHz is there are few WSPR stations active usually.

Maybe I shall try some 2-way HF QSOs using CW, PSK31, JT65HF or JT9-1 instead? All the while I am trying to avoid speaking to save my poor voice!


Anonymous said...

Hi Roger

You seem to be keeping your self occupied with your experiments on 160 Meters.


Anonymous said...

Hi Roger,

Looks like you have been busy - which is good !

Some interesting results.

I'm just wondering how much of the radiated signal is due to actual earth conduction, or more likely, due to radiation directly from the electrode connecting wires. Google Grass wire antenna.

The basic wire on the ground with an earth stake at the end is very much like a very low terminated Beverage antenna or Broadband Terminated Vee.

I think it may be worthwhile experimenting further.

1. What is the difference in WSPR reported S/N WRT a simple suspended wire antenna a few feet off the ground. Both could be modelled with EZNEC or similar. Do the measured results stack up with the modelled values ?

2. Does the antenna show any directional properties like a Beverage or Vee, which could give an indication to it's mode of operation ?

3. What happens when the earth spikes are disconnected from the ends of the wires, just leaving wires lying on the grass ?

4. What happens if the connecting wires are buried in the soil at different depths ?


Martin - G8JNJ

Roger G3XBM said...

Martin,I am unable to say. I believe the mechanism is mainly the "loop in the ground" at 630m and maybe 160m which becomes more effective as the skin depth increases (lower frequency). As one goes higher in frequency I am sure you may be right and the antenna mode changes.

Roger G3XBM said...

Martin, at the old QTH I experimented with raised wires for part of the loop (a LITTLE better only at 630m). Running the wire back along the grass is really just as good, suggesting the " loop in the ground" is quite large at 630m. My poor physical health (stroke) prevents any outside work currently.

Anonymous said...

Roger.. google "project Sanguine"
(there is a Wiki page) is worth a look. This is a VLF submarine transmitter, which used earthed electrodes over a big distance, and lots of input power to generate a few watts of radiated power. The "loop in the ground" version seems correct. They deliberately chose the site for low earth conductivity, and buried the electrodes in boreholes to force the loop to be as big as possible.
Hugh. G6AIG