In a previous e-mail, I stated that a Swedish ham's two-wire shunt feed
system increased his BW from 100 kHz to 110 kHz. That was in error.
I revisited those model files and here are the corrected values:
single-wire shunt = 90 kHz BW (2:1 SWR)
two-wire shunt = 130 kHz BW (2:1 SWR)
The increase in BW is about 44%.
SM4CAN's tower was 23m high with a 6-el 20-meter Yagi at 24m on a 15m
boom for top loading. This structure is 1/4-wave electrically at about
1.555 MHz. (about 0.3 wave at 1.83 MHz).
For a single-wire shunt, the 50-ohm tap was at 21m. The required
capacitor was 264 pF.
For his two-wire shunt (wires spaced 0.5m from each other), the 50-ohm
tap was at 23m (top of tower). The required cap was 557 pF.
In both models the shunt wires were #8AWG and the shunt wire(s) was
spaced about 0.5m from the tower.
I apologize for my error in remembering incorrectly that there was an
insignificant difference in BW between a single-wire and multiple-wire
shunt feed.
73, de Earl, K6SE
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