[Antennas] 2m Cubex Quad

Tue Apr 11 10:53:34 EDT 2006

John,
Since your desired operating frequency (144.5 MHz) has a wavelength about 
1% longer than the frequency at which the antenna is tuned (146.0 MHz), you 
should lengthen all of the elements by about 1% (roughly 13/16" for a 
nominally one-wavelength loop). This should preserve the radiation pattern 
at the lower frequency. Technically you should increase the spacing 
between elements by 1% as well, but you probably wouldn't notice the 
difference in performance. You will undoubtedly have to readjust the 
impedance matching system.
73,
Dave NB4J
At 04:00 AM 4/11/2006, you wrote:
>I have a 4 ele. cubex Quad that I would like to retune. It is
>currently resonate around 146.0 mhz and I would like to move it to
>144.5 mhz. I know it's not that far from where I want it now but the
>swr really starts to climb when I use it below 144.3 mhz.
>>I have several verticals for 2m fm work and use the quad for 2m ssb
>only, and my icom 746 is really agresive about cutting back power when
>it sees a less than perfect match.
>>So my question is. What are my options for retuning the antenna? I am
>open to all possibilities from adding wire to it, a tuning stub, a
>variable cap, or I suppose I could just use a transmatch at the
>transciver.
>>Thanks for your consideration
>John
>N7JL

--
David F. Kelley, Ph.D.
Assistant Professor
Electrical Engineering Dept.
Bucknell University
Lewisburg, PA 17837
(570) 577-1313
dkelley at bucknell.edu