David,
Here is the YO file for my 20 meter Yagis. They are on 48 foot booms. I
stack a pair of these at 50 and 100 feet. I would not recommend stacking
them at 70 and 140 feet because much of the time that will be higher than
optimum for the north Atlantic path.
All dimensions are in inches.
Each column is the same diameter
Each row is a different element, starting with the reflector.
A six element beam would require a boom length of 70 feet to get any
useful additional performance relative to this antenna.
73!
Frank
W3LPL
donovanf@sgate.com
W3LPL 5 Element 20M Yagi 48 Ft Boom
Height 2340.000
14.000 14.200 14.350 MHz
5 elements, inches
1.2500 1.1250 1.0000 0.8750 0.7500
0.0000 33.7500 50.2500 33.0000 33.0000 67.0000
86.0000 33.7500 50.2500 33.0000 33.0000 52.0000
171.0000 22.0000 47.8750 33.0000 33.0000 64.0000
349.0000 22.0000 31.2500 33.0000 33.0000 77.0000
570.0000 22.0000 43.7500 33.0000 33.0000 52.0000
Use the M and Tab keys to enter the following
T-match parameters:
Rod diameter: 0.5"
Rod Spacing: 6"
Rod Length: 48"
Lead Length: 3"
Series Cap: 99999 pf
Feed Z 200 ohms
Experience indicates that the driven element
tip must be lengthened to 62 inches, the
length that produces a modelled impedance of
+j20 ohms at 14.200 MHz
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