[amsat-bb] Stacking of dissimilar antennas

Chris Bryant 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:
> Friends,
> 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.
> 73
> Nitin [VU3TYG]
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