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Antennas & Propagation. A mixed bag from VLF to VHF Brian Austin G0GSF. The First Antenna?. …and The First Radio Signals?. Marconi’s antenna 1896. Oliver Lodge’s Biconical 1897. Marconi’s monster 1901. Ground Waves. The EM Spectrum. ELF=30 to 300 Hz. - PowerPoint PPT Presentation
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Project ‘Sanguine’ USN 1970sCarrier frequency 45 Hz
Submarine depth 250m
Range 6200 miles
RX antenna length 300m trailing wire
TX antenna length 1000km (total wire in grid)
Resistance: TX antenna 44 ohms
Radiation resistance 0.012 ohms
Radiation efficiency 0.027%
Antenna current (peak) 1095 amps
TX power 26.4MW
Data rate 1 bit/s
Trees as transmitters
• TX frequency: 450kHz
• TX power: 35W
• TX range: 35miles CW; 15miles AM.
• And it was directional!
Tree-to-Tree
• TX frequency: 4.65MHz
• TX power: 15W CW/SSB
• Horizontal RX antenna better than vertical!
G5RV performancewww.karinya.net/g3txq/g5rv/
Band Lowest SWR Worst SWR
160 >100 >100
80 3.2 12.6
40 4.9 5.9
30 48 50
20 2.5 3.7
17 32.1 33.6
15 6.1 12.9
12 3.6 4.6
10 51 60
The ‘ZS6BKW’ multiband
HF
Band
Centre
Freq. (MHz)
SWR
(min)
Band-width
(kHz)
40 7.10 1.1:1 360
20 14.20 1.1:1 270
17 18.10 1.3:1 380
12 24.92 1.4:1 260
10 28.97 1.4:1 400