[TowerTalk] Wilson 5 element 20 meter monobander

[Joe Subich, K4IK]

> From: Michael Tope
> 
> I think what everybody is trying to say is that for a fixed 40 ft
> boom length, you don't gain much by increasing the number of
> elements beyond 4. That doesn't mean that 5 can't or won't work
> as well as 4, it just means that 5 won't work much better than 4
> unless you lengthen the boom beyond 40 ft.

That depends on what you mean by "5 won't work much better than 4." 
If you are talking forward gain, you're correct - gain is 
proportional to boom length.  If you're talking about maintaining 
gain over more of the band, or SWR bandwidth, or maintaining F/R 
over more of the band, then the five element design may be "better" 
than a four element design on the same boom length.

For example, if one uses the YO 40 foot boom 5 element antenna as 
a starting point, forward gain (free space) is 9.95 +/- .07 dB 
across the entire band ... F/R is 24 +/- 1 dB across the entire 
band and SWR is less than 1.5:1 across the band.  If one element 
is removed, gain drops by less than .2 dB (9.8 +/- .3 dB) ... F/R 
drops to 18.5 +/- 5 dB and SWR bandwidth (1.5:1) becomes less 
than 300 KHz.  

Stretching the 5 element design to a 56 foot boom buys about 1 dB 
of gain over the 40 foot 5 element design ... F/R and SWR bandwidth 
remain about the same. 

73, 

   ... Joe, K4IK