[Top] [All Lists]

Re: [TowerTalk] dipole takeoff angles

Subject: Re: [TowerTalk] dipole takeoff angles
From: David Gilbert <>
Date: Mon, 25 Apr 2011 11:20:08 -0700
List-post: <">>
That depends upon a large number of factors.   VOAAREA, one of the 
applications packaged with VOACAP, will give you a nice pretty area map 
showing the bounces in all directions and their effect on signal 
strength for any set of parameters (time of year, time of day, solar 
flux level, frequency, etc).   You can even generate your own antenna 
file (essentially the antenna pattern) to tailor it to your own situation.

All of that is simply prediction, of course, but it's based upon a 
generally accepted computer model and a lot of historical data.

VOACAP/VOAAREA probably has the most versatility for evaluating various 
input conditions and displaying the results in various ways, but the 
user interface is unquestionably one of the clumsiest ever devised by 
man.  HAMCAP, which is actually just a better user interface for the 
VOACAP engine, is slightly more limited in options but is MUCH more 
straightforward to use.  Both programs are free.   I tend to use VOACAP 
to display path loss rather than signal strength or S/N ratio.  Path 
loss pretty much eliminates considerations of power level and local 
noise levels and therefore gives me a cleaner picture of raw 
propagation.  YMMV.

By the way, VOACAP also has the ability to display preferred takeoff 
angle as the output parameter, although even the author of the program 
states that takeoff angle is probably the least reliable in terms of 
supporting background data of all 20 parameters that VOACAP can 
display.  Still, it is rather amazing to see just how low an angle is 
optimum for most paths, including some that we would normally consider 
to prefer a higher angle.

Dave   AB7E

On 4/25/2011 6:59 AM, wrote:
> has anyone ever seen statistics on how many times a given signal bounces from 
> earth to ionosphere as it travels around the earth and what amount of loss is 
> involved each time it bounces?  David  K2DRN
> _______________________________________________
> _______________________________________________
> TowerTalk mailing list

TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>