On Fri, 3 Sep 2010, Kris Kirby wrote:
> > Once you get it figured out, PLEASE write up an article for 
> > Repeater-Builder for the rest of us!!
> 
> Make an "X" with dipole elements, and connect the feed harness to one 
> side, and connect the left and right sides together with 
> 1/4-wavelength of coax, wire, or coat-hanger. The antenna elements 
> should be on opposite sides of the mast.
> 
> Something about this tells me that the stack should have the next 
> section up rotated 90-degrees around vertical to eliminate nulls.
> 
> If you take that and try to build it all around the same point, it 
> starts looking like an imploded Lindenblad.

I could go further to say that it should be possible to do this with two 
DB-224 clones, the ones that hold the elements to the pipes with 
hose-clamps. Connect up all the feed harnesses as you normally would and 
connect the two by a -90 degree hybrid, or a 0-degree (in-phase) 
Wilkinson divider with a -90 degree section (1/4-wavelength) of coax on 
one leg, so that one antenna is fed -90 degrees (1/4-wavelength) from 
the other. 

Pasternak's article makes mention that these antennas are difficult to 
match. Things being as critical as they are, I would recommend tuning 
for minimum VSWR, since the receivers are hardly ever 50-ohms. 

This antenna may lend itself better to a split-antenna system without 
much separation between the circular antenna and the vertical antenna -- 
simply to avoid detuning the receiver duplexers if the antenna loading 
situation changes due to ice or other effects. 

--
Kris Kirby, KE4AHR
Disinformation Analyst

Reply via email to