I thought of that. If i moved the RB333 enclosures so that that were
pointing opposite directions with the dummy loads touching each other there
was no link and the client scan could see no AP even with the loads
touching.
--
Kurt Fankhauser
WAVELINC
P.O. Box 126
Bucyrus, OH 44820
419-562-6405
www.wavelinc.com


--------- Original Message --------
From: WISPA General List <wireless@wispa.org>
To: WISPA General List <wireless@wispa.org>
Subject: Re: [WISPA] RB333/433 eliminating self-interference test
Date: 04/29/09 12:13

> 
> 
> 
> 
>   
> 
> 
> Also, some dummy loads can act as a poor antenna.&nbsp; Was this part of
the
> experiment consistent both times?&nbsp; Maybe run some coax from the boxes
> separate directions and then attach the dummy loads?
> 
> Scott Carullo wrote:
> 
>   Another quick note...  if you have individual units why even mount them 
> like this inside a larger box?  Why not put individual RB411s in their own

> small box (say DCE 7x6x2) and put the box outside right under the antenna?
 
> Then you would have even more seperation and distribute you eggs a bit
more 
> too...
> 
> Scott Carullo
> Brevard Wireless
> 321-205-1100 x102
> 
> -------- Original Message --------
>   
>   
>     From: "Kurt Fankhauser" &lt;k...@wavelinc.com&gt;
> Sent: Wednesday, April 29, 2009 10:36 AM
> To: "WISPA General List" &lt;wireless@wispa.org&gt;
> Subject: [WISPA] RB333/433 eliminating self-interference test
> 
> About a week ago there was some discussion about 5ghz radio's being
> installed in the same board and causing self-interference on adjacent
> channels and possible even on the entire band thus decreasing throughput 
>     
>   
>   on
>   
>   
>     backhauls. Because even if you were operating on frequency's 5745 and 
>     
>   
>   5825
>   
>   
>     the two radio's would have side lobe harmonics that if installed in
the 
>     
>   
>   same
>   
>   
>     enclosure they would still "hear" each other at that short of
separation. 
>     
>   
>   I
>   
>   
>     decided to combat this problem and find a solution and share my 
>     
>   
>   experience
>   
>   
>     with the list. 
> 
>  
> 
> I installed a single XR5 card into 3 different RB433's with indoor
> enclosures. I also installed foil tape which I obtained from the local 
>     
>   
>   True
>   
>   
>     Value store for $2.49 on all the vent holes and unused bulkhead 
>     
>   
>   connector
>   
>   
>     holes. This was done in order to prevent RF side lobe leaks from the 
>     
>   
>   three
>   
>   
>     radio's that would escape from the indoor enclosures themselves.
Having 
>     
>   
>   only
>   
>   
>     1 card inside each enclosures I should not have a heat problem as the
> outdoor box will not be in direct sunlight. 
> 
>  
> 
> I then stacked all 3 enclosures on top of each other with dummy loads on
> each of the N-bulkhead connectors and did some testing. This is what I
> found:
> 
>  
> 
> I set the bottom board as AP and the middle board as Client on frequency
> 5825. Even with this close of separation the two XR5's could only see 
>     
>   
>   each
>   
>   
>     other at -83 on the same channel. With the top board connecting to the
> bottom board they could only see each other at -90. Keep in mind this is 
>     
>   
>   on
>   
>   
>     the same frequency so adjacent channels should be much less than that
> possibly even in the -100 ranges. Wish I had a spectrum analyzer. With 
>     
>   
>   two
>   
>   
>     boards separating the AP and Client there was no link at all. The two 
>     
>   
>   boards
>   
>   
>     could not even see each other in an AP scan.
> 
>  
> 
> Just as a comparison with the same radio's installed all on a RB600 not 
>     
>   
>   on
>   
>   
>     top of each other but in the adjacent mpci slots the radio's were all 
>     
>   
>   seeing
>   
>   
>     each other at -30's. So I gained roughly -55 db of separation by doing

>     
>   
>   it
>   
>   
>     this way. So all I would have to do now is make sure that the antennas

>     
>   
>   on
>   
>   
>     the tower have at least 10 foot of vertical separation and the
> self-interference problem should be gone and I should be enjoying much 
>     
>   
>   more
>   
>   
>     throughput!
> 
>  
> 
> Thoughts anyone?
> 
>  
> 
>  
> 
> Kurt Fankhauser
> WAVELINC
> P.O. Box 126
> Bucyrus, OH 44820
> 419-562-6405
> www.wavelinc.com
> 
>  
> 
>  
> 
>  
> 
> 
> 
> 
>     
>   
>  
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