6 Element 20m Beam on 44ft Boom
Designed by Nathan Miller NW3Z
The following plots show the 48’ boom antenna along with the new 44’ boom design, both as a straight, un-tapered element and as a tapered element.
The VSWR is excellent across the band and was set as a high priority during the optimization process. A second model of the tapered antenna was run with double the segments and the results correlate very closely.
The front-to-rear was the top optimization goal. Across the band, the worst case front-to-rear lobe is 25dB.
Gain was sacrificed to achieve the other goals, however it is only slightly less than the 48’ antenna. Such a small loss of gain is not even noticeable.
The following table shows the spacing of each element from the reflector, the diameter of each tapered segment and the length of each.
|
Diameter |
|||||
|
Spacing |
1.000 |
0.875 |
0.750 |
0.625 |
0.500 |
|
0.000 |
48.000 |
24.000 |
44.000 |
36.000 |
67.019 |
|
99.910 |
48.000 |
24.000 |
44.000 |
36.000 |
58.927 |
|
140.320 |
48.000 |
24.000 |
44.000 |
36.000 |
49.945 |
|
255.270 |
48.000 |
24.000 |
44.000 |
36.000 |
39.341 |
|
320.590 |
48.000 |
24.000 |
44.000 |
36.000 |
37.730 |
|
522.000 |
48.000 |
24.000 |
44.000 |
36.000 |
31.775 |
This table shows the un-tapered elements.
|
Spacing |
Diameter |
Length |
|
0 |
0.6985 |
211.93 |
|
99.91 |
0.7138 |
204.16 |
|
140.32 |
0.723 |
195.57 |
|
255.27 |
0.728 |
185.52 |
|
320.59 |
0.7308 |
183.99 |
|
522 |
0.7308 |
178.41 |