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© 2010 Arctic Diamonds - TF4M
Villi, TF3DX the designer of the Arctic King antenna worked JA7FUJ last night on 160 meters from his car.
This is the first time such a QSO takes place between Iceland and Japan.
To put this in perspective, with 100 W feeding the mobile whip – even perfectly tuned, only 1 W is radiated.
To compensate for the low efficiency of a mobile antenna, Villi drove to the sea shore where he was able to take advantage of the excellent conductivity of salt water. The noise from the city was also reduced considerably at this location.
Congratulations OM !
TF3DX/M
I finished building two new single wire Beverage antennas today which fill in some gaps in the coverage.
The Beverage Antennas at TF4M are as follows:
1: 0° = 320m
2: 14° = 170m
3: 60° = 225m
4: 100° = 300m
5: 132° = 380m
6: 143° = 350m
7: 194° = 170m
8: 280° = 300m
9: 312° = 380m
10: 323° = 350m
8 of these are fed into the K9AY RAS 8×2 Matrix antenna switch, which then feeds the receive antennas to two radios in any combination. Works extremely well.
The resonance of the Arctic King was made slightly high to enable accurate adjustments of system resonance to be made at the feedpoint.
A small choke was inserted in series with the elevated radials with the resulting SWR curve shown.
Resonance is adjusted completely separately from matching the resulting resistance (R) which is done with a 50 ohm to 12.5 ohm UNUN transformer.
The Radiation Resistance at resonance is 17.5 ohms (+/- 0.5ohms), which accounts for the slight SWR (1.4:1 at feed point) at resonance.
Modelling gives approximately 75% radiating efficiency and less than 1dB in ground losses.
