[amsat-bb] Stacking of dissimilar antennas
g3wie at crystalhobs.org.uk
Tue Jul 1 21:32:02 UTC 2014
When stacking antennas for different frequencies and you wish to
estimate the effect of, say, a 2m antenna on a 70cm antenna, you should
consider the capture area of the 2m antenna at 70cm, *not* at 2m.
Despite the physical size, the capture area is very small. That means
you can put the antennas much closer together than many people think.
WA5VJB did some measurements for 900MHz and another band which
illustrated this, and presented the results in a lecture to the UK
Microwave Group some years ago. He found he could put the antennas
almost touching with little effect on the radiation pattern. I did some
Eznec simulations for 2m and 70cm crossed yagi antennas spaced
horizontally at distances from 2.0m down to 0.8m which gave similar
answers. I have the pictures in a powerpoint file which I've emailed to
you directly as I don't know if this list supports attachments.
I built the antennas but then moved house before I could put them up. I
still haven't got there!
On 01/07/14 18:47, Nitin Muttin wrote:
> Need some help. I am planning to stack two 2 meter Cross Yagi and two 70 cms cross yagi on a H frame. Can some one guide me on the horizontal and vertical stacking distances that I need to maintained. I have some information for example from http://www.directivesystems.com/STACKING.htm but confused what should be the final configuration.
> Nitin [VU3TYG]
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