A Shortened 40-Meter Four-Element Sloping Dipole Array
A Shortened 40-Meter Four-Element Sloping Dipole Array
A Shortened 40-Meter Four-Element Sloping Dipole Array
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<strong>Shortened</strong> elements<br />
The tower is about 56 feet (17 meters) high, and two of the four guys are fastened to<br />
the house about 6 feet above ground - a serious problem. Consequently, with the<br />
maximum possible element length, shortened dipoles had to be used. My design,<br />
shown in fig.1, uses a 4,5 µH inductance in each leg. A coil 12,5 turns, 1,5 inches in<br />
diameter and 1,4 inches long, provides the value of inductance.<br />
<strong>Shortened</strong> <strong>40</strong> m dipole SWR vs. frequency<br />
4<br />
3,5<br />
3<br />
SWR<br />
2,5<br />
2<br />
1,5<br />
1<br />
6,8 6,9 7 7,1 7,2 7,3<br />
Frequency [MHz]<br />
Fig.2. SWR of the shortened <strong>40</strong> m elements. Antenna was tuned<br />
for lowest SWR over the European segment of the band.<br />
Note the SWR is less than 1:2,0 over 200 kHz of band width.<br />
SLOPEREN1.DOC Date: Page 2 of 5
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