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mutual coupling efects on antenna phase - RF Cafe Forums

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sag
 Post subject: mutual coupling efects on antenna phase
Posted: Sun Oct 29, 2006 3:22 pm 
 
Captain

Joined: Wed Apr 05, 2006 3:34 pm
Posts: 6
Hay all,

I want to know what is a "safe" distance of an antenna from another one so that they won't effect each other in the phase point of view (i.e ang(s21) will not be affected).

(the antennas are connected to separated receivers)

10x.


 
   
 
nubbage
 Post subject:
Posted: Mon Oct 30, 2006 4:51 am 
 
General
User avatar

Joined: Fri Feb 17, 2006 12:07 pm
Posts: 218
Location: London UK
It depends on the directivity of each antenna. Two highly directional antennas can be placed almost adjacent to each other.

A low gain system needs a spacing of several wavelengths, although a precise figure depends on the phase error you are prepared to accept or are able to measure.

If the antennas are completely independent, some isolation can be achieved by using opposite polarization.


 
   
 
sag
 Post subject:
Posted: Sat Nov 04, 2006 6:09 am 
 
Captain

Joined: Wed Apr 05, 2006 3:34 pm
Posts: 6
hay,

It's not so simple... first of all, if the antennas are patches, than at 90deg they each have a NULL and it's depth is about 30dB at all directiviteis.
2nd if the antennas are close to eachother than there are parazitics fiels created on eachother and that has a great affect.
3rd, in phase you are more sensitive so even a 30dBc signal changes you phase to about 1deg.....






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