[TowerTalk] vertical antenna ground loss

[Peter Voelpel]

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Steve Hunt
Sent: Samstag, 6. Dezember 2008 23:48
To: towertalk at contesting.com
Subject: Re: [TowerTalk] vertical antenna ground loss

Peter,

I hope you didn't fall into the trap of just comparing the optimum take-off
angles. It's quite possible for a dipole with a higher take-off angle to be
better than a vertical with a low take-off angle for DX work.

For example, I just compared the elevation pattern of a 45ft monopole
(blue) with the elevation pattern of a 20m half-wave at 40ft (red):

http://www.karinya.net/g3txq/dipole_vs_monopole.png

Even though the dipole has a higher optimum take-off angle it beats the
monopole at all low angles. When comparing antennas in this way it is VITAL
to overlay the patterns on the same scale. It's not sufficient to compare
optimum take-off angles.

73,
Steve G3TXQ

Peter Voelpel wrote:
>
> In all the cases studied and modeled, the vertical antenna had a lower 
> radiation pattern than a low hanging dipole  (it is like fairly 
> impossible for me to get a 1/2 wave 40 meter dipole up 1/2 wave over 
> the ground, so we used different realistic values, such as
> that dipole at 25 feet, 40 feet,  and 60 feet, respectively.   We
> compared the take off angles and radiation patterns with the
> angles and patterns for the 45 foot monopole vertical.   We
> modeled the same sort of setup for 160 meters,  80 meters, 40 meters, 
> and 20 meters.
>
> In all cases the dipole radiated at a slightly higher angle than the 
> vertical, which is why the vertical is a better choice, sometimes, 
> than the dipole for low band DXing.
>
>   

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Hi Steve,

I did not write what you quoted.
I already mentioned that a dipole at sufficient height beats the vertical
any time, except into the direction of its null

73
Peter