[TowerTalk] Take off angles, VOACAP, etcf.

[Joe Subich, K4IK]

> This is all quite fascinating. If you are designing an 
> antenna installation for hams (or, if as I am doing, you are 
> looking at optimizing phased arrays for hams), the ionospheric 
> effects might actually be less important than such things as the 
> antenna configuration on the other end of the (speculative) link 
> and the relative times of day, and, in the contesting scenario, 
> what all the other hams are doing.  

As I recall, the N6BV path data is a compilation of all angles  
over the entire solar cycle and were generated with isotropic 
radiation (with gain) on both ends.  Those angles with higher 
probability occur more often or last longer. 

The idea then, is to create an antenna system with either a 
big fat vertical lobe that covers ALL the desired angles or 
one with a more narrow, slewable, take off angle that can be 
adjusted to cover the entire range (e.g., a stack of yagis with 
selectable phasing and height).  

The problem of an antenna with too low a take-off angle is not 
as rare as one might think.  It shows itself every time a 
station with a big yagi on a very tall tower gets beat  by 
the guy down the street with a low tribander in the pile-up for 
a Dxpedition running a yagi at 20 or 30 feet

73, 

   ... Joe, K4IK