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: