[TowerTalk] Experience with phased verticals on 40m?

[Jim Lux]

On 9/30/12 12:18 PM, K8RI wrote:
> On 9/30/2012 8:28 AM, John Tait wrote:
>> I run a pair of 1/4 spaced verticals East/West, using the simple 84 deg
>> feed lines, and a 71 deg phasing line, from ON4UN's fourth edition, page
>> 11-9. It works very well for me, and is easy to build. It cost almost
>> nothing, and is very effective. Unless you can get to a sufficient
>> height, dipoles are cloud warmers, but good for the close in stuff. A
>> four square would be great, but if you don't have the space, a pair are
>> much better than one.  Well worth the effort.
>
> I ran a pair for many years when I lived near Breckenridge MI and they
> worked very well.  They were right at the East edge of the yard, with
> the road on the North side. After the crops were out, I'd move the
> northern most vertical to the East a bit and put the radials down for
> the winter.
>
> I'd like to try a 4 square, but I only have one acre and even a phased
> pair is pretty much out.  I might try putting up some out in the woods
> as I don't think the owner would care. OTOH I'd sure like to buy an acre
> adjoining me to the West and clean most of the trash trees out of there
> and keep the few good ones.
>


In theory, the big benefit from a 4 square is the very good nulls you 
can get on receive, and that doesn't require 1/4 wave spacing; it 
requires good control of phasing and amplitude, which these days, is 
fairly easy to get with a DSP approach (I'm thinking of Victor Kean, 
K1LT kind of schemes).

The forward gain is a lesser concern, although not negligible, but 
should also not require big spacings (just as you can get high gain in a 
multielement yagi).

The challenge with small (or uneven) spacings is that the the feed 
system isn't as simple as a Collins quad hybrid and 1/4 wave current 
forcing.  I'm not sure, though, that this is as big a deal these days. 
A computer controlled LC network, for instance, can get you there. 
Broadcast arrays have used lumped LC for decades.