[TowerTalk] Vert. 1/2 wave dipole vs Hori. 1/2 wave dipole?

[Richard (Rick) Karlquist]

You misunderstood what I said.

I said a HALF WAVE vertical fed from the bottom is essentially
the same as a half wave vertical dipole fed in the center.

I wasn't talking about ground mounted quarter wave verticals.

However, now that you brought it up, I have also compared
a quarter wave 20M vertical with 32 radials against a
half wave 20M vertical with no radials.  Can't tell the difference
on the air. (Both ground mounted).

Rick N6RK

Jim Brown wrote:
> On Sat, 14 Jun 2008 22:04:53 -0700, Richard (Rick) Karlquist wrote:
> 
>> These are essentially the same array, just different feed 
>> implementation.  There is no fundamental difference.
> 
> Yes and no. Remember that one of the most important properties of 
> any antenna installation is how it interacts with the earth in the 
> far field (that is, what does the first reflection do), which is 
> strongly affected by its height.  
> 
> A quarter-wave vertical typically has its feedpoint on the ground or 
> close to it, placing its current maxima close to the ground. The 
> CLOSEST a half wave dipole's feedpoint (current maxima) can be to 
> the ground is a quarter wave. This has MAJOR impact on the vertical 
> pattern. The Power Point pdf I cited earlier in this thread has NEC 
> models for a 40M dipole at various heights that I was able to 
> achieve here (by hanging it from one of my redwoods). None of these 
> was particularly thrilling at low angles, and raising the vertical 
> dipole simply improved its vertical pattern at higher angles. 
> 
> And I DO have this antenna rigged with the top of it at about 100 
> ft, I HAVE compared it to horizontal dipoles at that height, and the 
> horizontal dipoles kick its butt by 10 dB every day of the week. :)
> 
> 73,
> 
> Jim Brown K9YC
> 
> 
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
> 
>