It has been a long time, but when I use to do commercial towers, the 
minimum was 80% of height, so your 20 feet is good.
BTW, you might want to guy the top as well, but you're looking at at 
least 32 feet out for that.
73
Butch Bussen
wa0vjr
open Node 3148
Las Vegas


On Fri, 20 Feb 2009, 
David R. Basden wrote:

> I have a two section 40-foot tower I am going to put up.  I will guy
> it with three guy wires at the top of the lower 20-foot section.  I
> have forgotten the recommended distance out from the tower for the
> guy wires.  My intuition is to put the guys 20 feet out from the
> tower to make a 45-degree angle.  Do any of you recall whether that
> is the recommendation in the ARRL Antenna Book?
>
> Thank and 73 de W7OQ, Dave
>
>