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