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W3LPL Yagi Designs
This e-mail contains the YO file for the full size 3 element 40M Yagis on
48 foot booms at W3LPL, one at 190 feet and the other at 100 feet. These
antennas have been in use for 25 years with excellent success.
The design is a compromise between gain, front/back ratio and VSWR across
the entire band. A three element Yagi does not have enough variables to
allow a good compromise design covering the entire 40M band; therefore,
the design favors good f/b ratio and VSWR from 7000-7100 kHz, good gain
from 7000-7300 kHz and acceptable VSWR from 7150-7300 kHz.
K3LR has implemented a 4 element design on the same boom length that
solves the VSWR bandwidth problem of a 3 element 40M Yagi. I have not yet
added a fourth element to my 40M Yagis, but a candidate design is included
at the end of this e-mail, as a YO file. This design clearly demonstrates
the excellent VSWR performance improvement resulting from the addition of
a fourth element on the same boomlength.
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W3LPL 3 Element 40 Meter Yagi (as Built)
Height 2280.000
7.000 7.100 7.300 7.100 MHz
3 elements, inches
2.0000 1.8750 1.7500 1.6250 1.5000 1.3750 1.2500 1.1250 1.0000
0.0000 72.0000 121.5000 16.5000 16.5000 17.0000 17.5000 18.0000 18.0000 134.0000
258.0000 72.0000 121.5000 16.5000 16.5000 17.0000 17.5000 18.0000 18.0000 110.0000
564.0000 72.0000 96.0000 15.0000 15.5000 16.0000 16.0000 16.5000 17.0000 125.0000
Use the H key to set the elevation angle to 10
degrees. Use the M and Tab keys to enter the
following T-match parameters:
Rod Diameter 0.5"
Rod Spacing 10"
Rod Length 144"
Lead Length 6"
Series Cap 99999 pf
Feed Z 200 ohms
Experience indicates that the driven must be
lengthened to 125 inches, the length that
produces a modelled impedance of +j20 at 7.1 MHz
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W3LPL Wideband 4 Element 40M Yagi
Height 2280.000
7.000 7.100 7.300 7.100 MHz
4 elements, inches
2.0000 1.8750 1.7500 1.6250 1.5000 1.3750 1.2500 1.1250 1.0000
0.0000 72.0000 121.5000 16.5000 16.5000 17.0000 17.5000 18.0000 18.0000 134.0000
234.7897 72.0000 121.5000 16.5000 16.5000 17.0000 17.5000 18.0000 18.0000 120.0000
317.9102 72.0000 121.5000 15.0000 15.5000 16.0000 16.0000 16.5000 17.0000 117.0000
564.0000 72.0000 96.0000 15.0000 15.5000 16.0000 16.0000 16.5000 17.0000 125.0000
This design illustrates how a 4th element radically
improves the bandwidth of a 40M Yagi (thanx K3LR !)
Use the H key to set the elevation angle to 10
degrees. Use the M and Tab keys to enter the
following T-match parameters:
Rod Diameter 0.5"
Rod Spacing 10"
Rod Length 144"
Lead Length 6"
Series Cap 99999 pf
Feed Z 200 ohms
Experience indicates that the driven element tip
must be lengthened to 134 inches, the length that
produces a modelled impedance of +j20 at 7.15 MHz.
6 Element 15M Yagi 48 ft Boom
Height 2340.000
21.000 21.225 21.450 MHz
6 elements, inches
0.8750 0.7500
0.0000 72.0000 70.1822
50.5432 72.0000 60.2349
108.1917 72.0000 58.9181
235.5508 72.0000 55.5817
403.9829 72.0000 53.2540
570.0000 72.0000 46.1496
Use H key to set elevation angle to 3.5 degrees
T-match parameters:
Rod diameter 0.5"
Rod spacing 5"
Rod length 31"
Lead length 3"
Series Cap 99999 pf
Feed Z 200 ohms
Experience indicates that the driven element tip
must be lengthened to 67 inches, the length that
produces a modelled impedance of +j20 at 21.225 MHz
This e-mail contains the YO file for the 5 element 20M Yagi on a 48 foot
boom at W3LPL. Five of these antennas have been in use for the last
several years at 50, 100 and 200 feet; operated individually and in
stacked pairs.
This design provides an excellent compromise between gain, front/back
ratio and VSWR across the entire band while avoiding a low feedpoint
impedance often found in other designs.
73
Frank
W3LPL
donovanf@sgate.com
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W3LPL 5 Element 20M Yagi 48 Ft Boom (as built)
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
Several folks asked if I had a decent 10M antenna...
This 8 element Yagi does very well!
One eagle eyed reader noticed a typo in the T-match rod length
in the Note file for my 6 element 15M Yagi (I sure wish YO stored
the modelled matching network parameters, instead of having to manually
type them into the Note file!). The correct T-match rod length for the
15M 6 element Yagi is 36 inches, not 31 inches.
73
Frank
W3LPL
donovanf@sgate.com
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W3LPL 8-Element 10M Yagi 47 ft boom
Height 2340.000
28.000 28.400 28.900 28.534 MHz
8 elements, inches
0.8750 0.7500
0.0000 72.0000 33.5000
50.0000 72.0000 25.7500
90.0000 72.0000 23.7500
164.0000 72.0000 20.2500
245.0000 72.0000 21.0000
340.0000 72.0000 20.5000
451.0000 72.0000 19.7500
558.0000 72.0000 14.2500
Use the H key to set the elevation angle to 2.5
degrees. Use the M and Tab keys to set the
following T-match parameters:
Rod Diameter: 0.5"
Rod Spacing: 4"
Rod Length: 24"
Lead Length 3"
Series Cap 99999 pf
Feed Z 200 ohms
When constructing this antenna, the actual driven
element tip length must be set to 29 inches, the
length that corresponds to a modelled impedance
of +j20 ohms in YO
David Robbins, K1TTT K1TTT@arrl.net