30M 3-Element Vertical Yagi:
Assuming a frequency of 10.100 MHz, 1" diameter AL vertical elements (all
starting at 6" above ground, and #12 wire horizontal elements 6" ABOVE
GROUND
I started out with a YO optimized 3-element 20M Yagi and scaled it to 30M
At 0' 0" on the "boom": Ref vertical element 25' 7.7", 2 horizontal
elements each 25' 7.7" at 90 degrees to "boom"
At 13' 4" on the "boom": DE vertical element 24' 1.2", 2 horizontal elements
each 24' 1.2" at 90 degrees to "boom"
At 29' 11" on the "boom": Dir vertical element 23' 5.8", 2 horizontal
elements each 23' 5.8" at 90 degrees to "boom"
EZNEC+ v5.0.66 calculates:
About 5dBi gain at 20-25 degrees takeoff, about 14 dB front-to-back, and a
feed-point impedance of 11.66 + J 5.979 ohms.
NOTE:
At a 5 degree takeoff angle (good angle for NA to EU), this antenna has
practically the same forward gain as a 30M dipole at 70'. No significant
improvement. BUT, this antenna does have some F to B, and a MUCH better
overhead null. (The 30M dipole at 70' has a major lobe straight up.) So if
some F to B and a deep overhead null is important to you this antenna would
provide significant improvement.
Marsh, KA5M
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