[Antennas] Would vertical be better than yagi?

[DJ5IL@aol.com]

W1CG wrote:

> I always thought the Yagi had a lower angle of radiation than a dipole whe=
n=20
> both antenna were at very low heights. =20

AA4NU wrote:

> Charles is correct, his models are pretty much on the mark. What he has
> done is to remind us of the impact of using a directional array, as in
> either a parasitic, or driven array at lower heights may, due to the patte=
rn
> being changed, actually lower the average angle of radiation ...


Thanks for the .EZ files, Chas. I was really able to verify your results and=
=20
both of you are absolutely right: The addition of parasitic or driven=20
elements indeed lowers the the radiation angle of an antenna and the lower=20
the height above ground the more pronounced is this effect. Obviously, at lo=
w=20
heights it is not permissible to consider the antenna to be a point-source o=
f=20
radiation and I assume that the lowering of radiation angle increases with=20
element spacing. I compared a Dipole and 3el.-Yagi on 14 MHz at different=20
heights above average ground (conductivity 5 mS, dielectric constant 13, hig=
h=20
accuracy ground model) with EzNEC 3.0, here are the results for max. lobe=20
gain and elevation angle:

@ 5m (Lambda/4): Dipole 5.8 dBi @ 69=B0 / Yagi 9.8 dBi @ 39=B0
@ 10m (Lambda/2): Dipole 7.1 dBi @ 30=B0 / Yagi 12.2 dBi @ 26=B0
@ 20m (Lambda): Dipole 7.4 dBi @ 15=B0 / Yagi 13.4 dBi @ 14=B0

The results clearly support your point. Interesting discussion - This is a=20
new and very valuable finding for me, thank you !

73
Karl, DJ5IL