Community discussions

 
User avatar
taglio
Frequent Visitor
Frequent Visitor
Topic Author
Posts: 97
Joined: Wed Nov 12, 2008 4:55 pm
Location: 34T, Barcelona, Spain

MIMO antennas. To be or not to be.... this is the question!

Thu Mar 25, 2010 5:36 pm

Hi there,

please help me :? i don't understand how i have to choose MIMO antennas.

In the actuality i use mikrotik, ubiquiti and compex MIMO radios, all 2x2 MIMO.

I have in my knowledge a big lack...i don't understand what kind of MIMO antenna i have to use in my real world application.

Simply imagine a very known scenario.... A tower with 3 sector antennas of 120 degrees for the base station and number of subscriber with panel [or grid if you can find in the marquet {WHEREEEE ????}] antennas.

The question of 1 million of dollar is:

The antennas would have two [or three....] "modules" [or inside antenna.. i don't know the exact name] that will work in the same polarity, or i have two use different polarity [vertical, horizontal and 45 degree....].

In my opinion i will have to use antennas with same polarity modules.... but.... per examples Mars [http://www.mars-antennas.com/] sales dpto say to me that i have to use different polarization... .and other example in the data-sheet of of AirMax5 Sectors antennas [http://ubnt.com/downloads/AirMax5GSectors.pdf] you can see that those antennas use different polarization...

What is your real world experience MK guys???

Best Regards,

RG.
.mhavoc world
 
JorgeAmaral
Trainer
Trainer
Posts: 199
Joined: Wed Mar 04, 2009 11:53 pm
Location: /ip route add type=blackhole

Re: MIMO antennas. To be or not to be.... this is the questi

Thu Mar 25, 2010 6:15 pm

Try to understand this: http://en.wikipedia.org/wiki/IEEE_802.11n-2009

And the search google for: spatial diversity technology

802.11n 2x2 is based on spatial streams, so you need to have antennas with different polarization.

Right now their is a lack in dual polarization antennas. We need to wait for the market to start supplying these.

Kindly regards,

Jorge Amaral
 
User avatar
taglio
Frequent Visitor
Frequent Visitor
Topic Author
Posts: 97
Joined: Wed Nov 12, 2008 4:55 pm
Location: 34T, Barcelona, Spain

Re: MIMO antennas. To be or not to be.... this is the questi

Thu Mar 25, 2010 6:36 pm

Thank you for rapid reply.

Ok i can understand this for professional equipment connection [base station + CPE subscriber].

But let me speak about connection between a MIMO AP [simply image routerboard 411A + an R52N radio] and netbooks or notebooks or pda..... and so on.

No i have two MIMO chain on the radio..... The radio on those hosts have dual polarity antennas???????? I don't think so.... i don't have to use simply to omnidireccional normal antennas?

Thank you,

RG
.mhavoc world
 
InoX
Forum Guru
Forum Guru
Posts: 1963
Joined: Tue Jan 09, 2007 6:44 pm

Re: MIMO antennas. To be or not to be.... this is the questi

Thu Mar 25, 2010 7:19 pm

mimo works also with same polarity. For example we use a dual feeder for RocketM, H polarised only and works very good. A simple router has only 2-3 antennas of the same polarisation.
 
JorgeAmaral
Trainer
Trainer
Posts: 199
Joined: Wed Mar 04, 2009 11:53 pm
Location: /ip route add type=blackhole

Re: MIMO antennas. To be or not to be.... this is the questi

Thu Mar 25, 2010 8:39 pm

If it works, yes, is it the better approach? no

The principle off spatial stream is different paths.

From intel website:
MIMO makes antennas work smarter by enabling them to combine data streams arriving from different paths and at different times to effectively increase receiver signal-capturing power. Smart antennas use spatial diversity technology, which puts surplus antennas to good use. If there are more antennas than spatial streams, as in a 2x3 (two transmitting, three receiving) antenna configuration, then the third antenna can add receiver diversity and increase range.

With same polarity, there is a big change of receiving signals with the same path, and you will not benefit of spatial stream.

Kindly regards,

Jorge Amaral
 
Muqatil
Trainer
Trainer
Posts: 574
Joined: Mon Mar 03, 2008 1:03 pm
Location: London - UK
Contact:

Re: MIMO antennas. To be or not to be.... this is the questi

Thu Mar 25, 2010 11:50 pm

[OT] Jorge, can you contact me on skype? :) [/OT]
Renato Bernardi

skype: medtech5
 
User avatar
taglio
Frequent Visitor
Frequent Visitor
Topic Author
Posts: 97
Joined: Wed Nov 12, 2008 4:55 pm
Location: 34T, Barcelona, Spain

Re: MIMO antennas. To be or not to be.... this is the questi

Fri Mar 26, 2010 11:42 am

Ok, so it seems that is better use different pol. but we can use same polarity antennas [and we lost some benefits].

Internal laptop MIMO antennas use different pol. antennas?? Or simply use 1 chain?

Regards,

RG
.mhavoc world
 
JorgeAmaral
Trainer
Trainer
Posts: 199
Joined: Wed Mar 04, 2009 11:53 pm
Location: /ip route add type=blackhole

Re: MIMO antennas. To be or not to be.... this is the questi

Fri Mar 26, 2010 9:38 pm

[OT] Jorge, can you contact me on skype? :) [/OT]
Of course ;)!!!
 
User avatar
taglio
Frequent Visitor
Frequent Visitor
Topic Author
Posts: 97
Joined: Wed Nov 12, 2008 4:55 pm
Location: 34T, Barcelona, Spain

Re: MIMO antennas. To be or not to be.... this is the questi

Mon Mar 29, 2010 11:46 am

PONG...
.mhavoc world

Who is online

Users browsing this forum: No registered users and 9 guests