Experyment with antenna earth elektrode about 600m long

Successful experiment with earth dipole about 150m long encouraged me to experiment with a longer antenna about 600m long. I used industrial earthing on one side and steel beam with ‘C’ cross section immersed in the water on the shore of a small lake served as the other electrode. I used industrial earthing on one side. The antenna consisted of two wires about 150m (symmetric cable) and 600m (PKL) long,

The resistance of the antenna for DC was about 1kΩ.

The PKL cable resistance of about 600m was about 20Ω

The symmetrical line resistance of about 150m was about 70Ω

The loss resistance for the cables was about 90Ω

 

Antenna analyser measurement according to SQ1GU with an option of work under 800kHz ratio 1:4

Antenna analyser measurement according to SQ1GU with an option of work under 800kHz ratio 1:9

Antenna analyser measurement according to SQ1GU with an option of work under 800kHz ratio 1:16

For a 600m long earth dipole, minima and impedance maxima are visible, which I can readily interpret as resonant.

Impedance in the 630m band was about 450Ω. ID-Elektronik SWR-meter (135kHz-10MHz) measured the standing wave ratio in 472kHz was ca. 1,25, which allowed for successful tests of transmission and receipt in 630 m. Significant QRN of the approaching summer was the cause of small 472kHz activity but it allowed my signal to be received  in Norway (LA8AV), Poland (SP5XSB) and I managed to receive signals from Germany (DK8NI) in WSPR mode.

The power of the test transmitter was 28W

The next experiments will be held in autumn with antenna more than 2km long

Link to the first 150m dipole experiment below:

 

Próby z anteną dipol ziemny

Decoding a 7-character ebnaut message on 6470Hz

On 3 June 2017 Stefan DK7FC did an 7 hour ebnaut transmission on 6470Hz with 7 characters. Previously i’ve been able to receive 2-3 character massages sent in a similar amount of time, however 7 characters seemed to be unreceivable. This article shows how the message was decoded, and may be useful to people starting to use linux and/or vlfrx-tools.
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Earth Electrode Antenna Tests

I conducted my first tests with earth electrode antenna in the nineties with the use of hot water installation. While drilling a well on my piece of land in the countryside I thought this could be just the right moment to explore this idea a bit more. A test drill for 5 meters provided a hole where I put an electrode. However, the soil in the hole was utterly dry and the electrode was not covered with it – it was just a two meters long aluminium L-beam. High resistance of this connection apparently influenced the antenna’s efficiency. A steel beam with ‘L’ cross section immersed in the water on the shore of a small lake served as the other electrode. The distance between the two electrodes was ca. 150 meters.

 

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6470Hz transmission by DK7FC succesfuly received at SQ5BPF (900km distance)

Stefan DK7FC has been recently transmitting on 6470Hz (46km wavelength) from a stationary antenna between two buildings.

The Ebnaut transmissions were received by Paul Nicholson (England) and Jacek SQ5BPF (Poland) at a distance of 900km (IN49IK to KO02MD).

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