

What is the Impact of Antenna Array on Link Budget  RF Cafe
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Michael 
Post subject: What is the impact of antenna array on link budget
Posted: Thu Apr 23, 2009 9:35 am


Joined: Thu Apr 23, 2009 9:17 am
Posts: 2 
I have N antenna elements Tx array communicating
with M antenna elements Rx array.
By how much will the link improve ? by
20LogN + 10LogM or by 20LogN + 20LogM ? Why?
(Compared to same link with just single
identical antenna and same power, NF, distance
etc)
Thanks Michael





nubbage 
Post subject: Re: What is the impact of antenna array on link budget
Posted: Mon Apr 27, 2009 7:49 am



General 

Joined: Fri Feb 17, 2006 12:07 pm
Posts: 236 Location: London UK

My vote is 10*LOG(M+N) plus a fudgefactor,
and assuming the antennas are still in the Far
Field region.
_________________ At bottom, life is
all about Sucking in and blowing out.





Michael 
Post subject: Re: What is the impact of antenna array on link budget
Posted: Wed Apr 29, 2009 4:16 pm


Joined: Thu Apr 23, 2009 9:17 am
Posts: 2 
Thank you nubbage, Could you reconsider please
(I think differently at least on Tx  why do
you thin I am wrong? )
Given the assumption
of the original single antenna link has the
same parameters to the NTx/ MRx case  same
output power per antenna, NF per antenna, etc
+ no reflections, line of sight, ideal spatial
summing at the max gain direction, array max
gain direction same as the single antenna max
gain direction, and any other assumption that
minimizes the problem to the simple one.
For the Tx antenna side, for sure fields
of the N antenna sum perfectly. So if at point
P in the single antenna case field was for example
E it will become now N*E. (The E vectors are
all in the same size and direction according
to the assumptions above). Therefore the
transmitted power which is proportional to E^2
willl follow the 20*LogN at point P. So,
the antenna gain in the link budget will increase
by 20*LogN compared to the N=1 case. i.e.
at point P
What happens on the Rx side?


Posted 11/12/2012



