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Re: [TowerTalk] ground radial length vs antenna height?

Subject: Re: [TowerTalk] ground radial length vs antenna height?
From: Jim Lux <>
Reply-to: Jim Lux <>
Date: Wed, 27 Aug 2008 10:23:46 -0700 (GMT-07:00)
List-post: <">>

-----Original Message-----
>From: Chris Adams <>
>Sent: Aug 27, 2008 10:11 AM
>Subject: Re: [TowerTalk] ground radial length vs antenna height?
>It seems to me that the takeoff angle is going to be primarily 
>determined by the characteristics of the ground outside the radial 
>field.  For example, to get low takeoff angles, requires reflection of 
>the signal, with the correct phase, a long distance from the radial 
>field.  Whether this reflection takes place, and how efficiently it 
>happens is dependent on the ground characteristics at that distance. 

Indeed.. flood your neighbor's yard with salt water...

>The efficiency of the vertical is directly affected by the number of 

and their length.  There are points of diminishing returns, though.  The rule 
of thumbs:
1) radials as long as the antenna is high
2) enough radials that the ends are some small fraction of a wavelength apart.

If you wanted to get fancy, you could lay a branching tree network of some 
sort, to keep the spacing between wires roughly constant.

It's a labor vs cost of materials vs incremental performance thing.

BTW, I recall that there's not a huge effect from wire size (for radials laying 
on the ground or buried shallow), so you pick your wire size  for mechanical 
properties and cost. (no matter how small the wire is, it's a heck of a lot 
better conductor than some amount of soil) 
>> ...N6LF has also published some excellent work on radial systems. It's 
>> on his website. Google to find it. 

yes, although his optimizations didn't necessarily trade appropriate parameters 
(i.e. if your question is "how do I best use X feet total of wire" that's 
answered, but the real question is "how do I best use labor hours at $X/hr and 
copper at $Y/pound"

(and bearing in mind that labor cost for hams is highly nonlinear.. the first 
couple hours are free, but as the sun gets hotter, and your back starts hurting 
more from stringing all that wire, the notional hourly rate starts to rise 

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