Yagi-Uda antenna design parameters
These were published in 1968 based on experimental results.
I don't totally get them.
Shouldn't R be slightly larger than .5 if the drive element F is .5?
d is the diameter of the elements
Optimal Lengths for Yagi-Uda Elements, for Distinct Boom Lengths
|Boom Length of Yagi-Uda Array, in λ|
The ACTUAL likely source for the above table might be
the The NBS Yagi Report.
It appears that the reflector is short because they used
a folded dipole (loop) instead of a half-wave dipole. dang.
Still scouring this report for dimensions of the folded dipole (loop)
|Spacing between directors, (SD/λ)
Impedance of a typical dipole is around 70 ohms, close to 75 typical for coax feed.
The folded dipole Z ir roughly 4* as high, 280 ohms, which is close to the 300 ohms for typical for twin-lead transmissions lines.
Folded dipoles, center driven, resonate at 0.5λ, 1.5λ,...
driven from the side, they resonate at integer multiples of λ
Rough guide for typical 1/2 wave dipole resonator:
- Reflector 5% longer than driver
- Director 5% shorter than driver
- Reflector spacing between .1 and .25 λ (.2*λ typical)
- Director spacing between .1 and .5 λ, depends on specs and number of directors
Last modified: Tue Oct 9 05:51:19 MDT 2012