Wireless Access

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Access network design for branch, remote, outdoor and campus locations with Aruba access points, and mobility controllers.
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Minimizing back lobes

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  • 1.  Minimizing back lobes

    Posted Apr 13, 2020 07:30 PM

    Hello all;


    I'm getting ready to put some AP-515 in a high ceiling (~25') lecture hall with a 60 seat capacity.  The building is a split academic/residence hall, and the next floor up is residence. Because of politics, the residence wifi is not owned or managed by us, nor is it Aruba equipment.


    I'm trying to minimize propagation through the ceiling, so my student devices won't be clinging to eduroam when they are supposed to be on the residence wifi.  This has me considering using 514's with external antennas instead.


    Looking at the ordering guide, I seem to have the choice of using attached antennas (ANT-20) to give me a very omnidirectional pattern with less backlobes, ANT-40 to give me more of a funnel pattern, or moving to the wall with the ATN-45 or 48.


    I'm hoping to get some funding to have a RF engineer take a look at this, but times being what they are that may not be possible. So does anyone here have some experience they can share with this type of environment?




  • 2.  RE: Minimizing back lobes

    Posted Apr 14, 2020 08:58 AM

    First do a physical test to see the actual propagation through the floor.  In an open environment like an auditorium the transmit power on the AP would be low in the first place.  Depending on the material in the floor above the APs, it would be attenuated even further.  I would mount an AP, set the TX power at 12 on he 5ghz band and do a site survey on the floor above before even considering external antennas.

  • 3.  RE: Minimizing back lobes

    Posted Apr 14, 2020 09:02 AM

    Mmmm.  Left out a critical piece of info, sorry.  Building isn't built yet.


    That said, that's the kind of experience I'm looking for.  Thanks.

  • 4.  RE: Minimizing back lobes

    Posted Apr 14, 2020 09:07 AM

    I would hire someone who you could tell the full story to and have them advise you.

  • 5.  RE: Minimizing back lobes

    Posted Apr 14, 2020 09:22 AM

    Well, yes, that would be my first choice. Just hoping to tap into the community's experience. So far the consensus is that external antennas are a last resort for typical indoor applications.

  • 6.  RE: Minimizing back lobes
    Best Answer

    Posted Apr 14, 2020 11:59 AM

    Hi Andrew,


    If you want check this guide https://community.arubanetworks.com/aruba/attachments/aruba/Aruba-VRDs/54/5/Aruba_VHD_VRD_Planning_Guide.pdf page 27 onwards.. It has some nice best practice coverage strategies for such scenarios (I do understand your case is not VHD requirement but the same concepts apply)

  • 7.  RE: Minimizing back lobes

    Posted Apr 14, 2020 12:58 PM

    Thanks Ayman.


    This is very helpful.  Much easier to read than antenna plots.