[TowerTalk] vertical antenna ground loss

[Steve Hunt]

Here's another example.

40m half-wave dipole at 40ft vs 45ft monople:
http://www.karinya.net/g3txq/dipole_vs_monopole2.png

Notice that the dipole "take-off angle" is 51 degrees compared to the 
monopole's 24 degrees, and yet they are both very close at all low angles.

Steve G3TXQ

Steve Hunt wrote:
> 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.
>>
>>   
>>     
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>