[TowerTalk] 80 M / 160 M dipole

[Jim Brown]

On Sun, 19 Feb 2006 03:20:10 +0000, Ed Stallman wrote:

>Any problem with putting both 80 M / 160 M dipole on one feed 
line?

No problem at all -- in fact, it works quite well. I use 2-wire 
and 3-wire dipoles extensively. I use spacers cut from 1/2" PVC 
conduit that puts the dipoles about 7 inches apart. At W6BX, I 
have a dipole for 20/15/10, another for 40/30/20, and one for 
160/80/40. My standard Field Day setup includes two 20/15/10 3-
wire dipoles at 90 degrees to each other on separate feedlines. 

The 160 antenna at W6BX is a full size two-wire dipole on 80 and 
40, with loading coils added to make it resonate on 160 (total 
length about 170 ft). Loading coils came from Barry at HyPower 
Antenna Company. Google to find them. It works VERY well. This 
particular antenna is the broadest antenna I have ever seen for 
75/80 -- it's tuned for 3.55 MHz, stays below 3:1 from 3.5 - 4 
MHz, and is below 2:1 for most of the band. 

For a 3-wire dipole, cut spacers about 18 inches long, and drill 
holes about 7.5 inches apart. You can lock the spacers in place by 
soldering copper around them on one of the dipole conductors (that 
conductor must be bare or stripped). 

The ARRL Handbook says that the dipoles will interact slightly 
with each other to modify their resonant frequency by a few 
percent. I have not been able to see this effect. 

73,

Jim Brown K9YC