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Contributor I

Down-Tilt vs Semi Directional Antennas

I have a production facility with ceilings around seven to eight metres high.   The rooms are largely open plan with machinery in the centre of each room.

 

I would traditionally use semi directional antennas aimed at the ground but I was wondering if the down-tilt antennas could be utilised and, if so, what type of horizontal coverage I could expect?

 

I have looked at a number of the Aruba design guides and they show the down-tilt antenna propagation like a street light but are they really that downward focused?

Aruba

Re: Down-Tilt vs Semi Directional Antennas

The Aruba AP standard design for the past several models is downtilt.  Deployments with high ceilings do extremely well with these APs on the ceiling.  I have done deployments higher than the ones you are indicating with good success with the embedded downtilt antennas.

 

This simplifies your installation, maintenance, costing and asthetics...all good things, along with great performance..


JF

Contributor I

Re: Down-Tilt vs Semi Directional Antennas

JF, how have you found the horizontal signal propagation down at ground level?

I had noticed that the 105, 135 and 225 access points have integrated down-tilt antennas. This is certainly a point of difference with other enterprise vendors who are using higher gain omni-directional antennas.
Aruba

Re: Down-Tilt vs Semi Directional Antennas

Propagatiion has been very good in those environments, especially when its wide-open in the case of manufacturing.   I use the AP-105 style APs in warehouses, shops, atriums and the like with good success.  

Re: Down-Tilt vs Semi Directional Antennas

What would you use on celiings that are not that high, i mean in a normal office, maybe 3m of high...

I mean not a warehouse were the ceiling is high and the downtilt antena can do it really good.

 

Cheers

Carlos

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Product Manager - Aruba Networks
Alternetworks Corp

Re: Down-Tilt vs Semi Directional Antennas

Do you use AP 104 with omnidirectional Antennas

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Product Manager - Aruba Networks
Alternetworks Corp
Aruba

Re: Down-Tilt vs Semi Directional Antennas

My Approach has been AP-105 (and AP-135) even in the office buildings.   My approach/plan is always based upon a 5 GHz layout, so the number of APs on the plan/grid/floorplan is sufficient to cover all areas even with 'normal' ceiling heights (e.g. ~9 feet).

  

With the newer APs available (AP-225 and AP-115) I will continue to avoid external antenna deployments and use those  in the same manner.     Substituting in AP-225 where dot11ac/high throughput is required and AP-115 where dot11n/higher throughput is required.

 

External antenna wise, indoors at least, is an extreme rarity in my designs.  So far so good, after 6+ years here designing Aruba Networks and another 11 years prior at other companies on similar projects.

 

JF 

Contributor I

Re: Down-Tilt vs Semi Directional Antennas

I have another site that has a number of "open plan" areas with a 2.7m ceiling but there is only approximately 1.5m between the top of the divider walls and the ceiling.  This area has a standard density of office desks but a each desk is separated by a divider wall.

 

In a non-Aruba deployment I would use a 6 dBi omni-directional antenna but with the AP-105, AP-135 and AP-225 having integrated down-tilt antennas what would be a suitable access point/antenna combination?

Guru Elite

Re: Down-Tilt vs Semi Directional Antennas

Crowdie,

 

It is best that you use the Visual RF offline planning tool   to get an idea of your horizontal coverage for your specific space.  Also, if you have an AP105, you should configure it as a site survey AP and measure your coverage using a TX power of 12 in the space based on the output of the Visual RF tool to see your actual coverage.  

 

The AP105s, 135s and 225 are deployed in areas with 3M ceilings; you just need to test it to see if it specifically works in your space.  In spaces with multiple floors, you need to stagger the AP deployment, since that RF might been seen on floors below/above due to the downtilt pattern.  In that case, make sure you do not run the APs at full power to limit floor-to-floor propagation.  You also might want to not deploy in hallways so that access points can leverage room to room attenuation so that access points do not have good RF line-of-sight vs. deploying in rooms.

 

Again, this is general advice on what to avoid and your specific space will determine what you can do.  Please see the Indoor 802.11n VRD here:  http://www.arubanetworks.com/wp-content/uploads/Indoor80211n_2012-05-31.pdf for detailed instructions.

 



Colin Joseph
Aruba Customer Engineering

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