ANTENNAS FOR 100 POUND DXPEDITIONS 6.5
Force-12 Sigma-5 on 17 meters As we move down in frequency the dimensions of the antenna become smaller when compared to the size of a full-wave. The bottom two bands (17m & 20m) require significantly more loading that the others. The loading for 17 meters is shown below. -------------- LOADS (RLC Type) -------------No.
Specified Pos. Wire #
Actual Pos.
% From E1
% From E1
Seg
L
C
(ohms)
R
(uH)
(pF)
R Freq (MHz)
Type
1
2
47.00
47.73
11
Open
1.92
Open
18.1
Par
2
2
55.00
56.82
13
Open
1.92
Open
18.1
Par
3
2
50.00
52.27
12
Short
0.52
Short
0
Ser
This provides a nearly flat SWR curve over the whole 100 KHz of the band.
SWR predicted by model
SWR measured by AntennaSmith
Figure 57 SWR for Force-12 Sigma-5 on 17 meters The far-field plot for the Sigma-5 over good ground on 17m appears below.
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