[TowerTalk] HFTA

[Pete Smith]

Yes, by all means, look at the descriptions in the Antenna Book and on 
the ARRL web site.  I'm not sure if it is mentioned there, but there's 
one added consideration. I think I'm correct to describe HFTA and its 
predecessors as two-dimensional - that is, in calculating the effects of 
terrain on a signal being radiated on a given azimuth, the program only 
considers reflection and diffraction occurring *in the plane* defined by 
the azimuth and the tower base.  Any effects from terrain that slopes 
*across* the plane are not calculated.  I have no idea, in practice, how 
large such effects might be, but it seems worth bringing up.  I can 
visualize "funneling" effects that could result from a signal passing 
through a steep-sided deep valley between two mountains, for example.

73, Pete N4ZR


On 4/25/2010 9:31 AM, Jim Brown wrote:
> On Sun, 25 Apr 2010 03:55:08 -0500, Barry Merrill wrote:
>
>    
>> Since you brought it up, what is HFTa'S
>> optimum slope angle and distance for maximum gain?
>> I assume it's different for each HF band?
>>      
> Study the discussion of HFTA in the ARRL Antenna Book.
>
> 73,
>
> Jim K9YC
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>