Forum

Hello everybody.

I don’t have many experience with external antennae and therefore have some questions to a project where I have to use an access point that is only available with external antennae connectors.

I have to replace ten existing 11.a/g access points by new access points. The existing access point positions and cabling should be used. The old access points have omni directional antennae and they are mainly mounted at walls or pillars.

The following antennae are available for the desired access point model:

WS-AO-DT05120-1                          Outdoor, 2.3-2.7/4.9-6.1 GHz, Triple-feed, 5 dBi, 120 deg, sector with reverse polarity type-N plug connector

WS-AIO-2S18018                             Indoor/Outdoor, 2.3-2.5 GHz, 18 dBi, 18 deg, panel antenna with reverse polarity type-N jack connector

WS-AO-2S10360                              Outdoor, 2.4 GHz, 10 dBi, Omni baton with reverse polarity type-N jack connector

WS-AO-5S10360                              Outdoor, 5.7-5.8 GHz, 10dBi, Omni baton with reverse polarity type-N jack connector

WS-AO-DS05360                             Outdoor, 2.4-2.5/5.15-5.875 GHz, 5 dBi, Omni baton antenna with reverse polarity type-N jack connector

WS-AO-5D16060                             Outdoor, 5.15-5.875 GHz, Dual-polarization 16 dBi, 60 deg, sector antenna with reverse polarity type-N jack connector

WS-AO-5D23009                             Outdoor, 5.15-5.875 GHz, Dual-polarization, 23 dBi, 9 deg, panel antenna with reverse polarity type-N jack connector

WS-AO-DX13025                             Outdoor, 2.4-2.5/5.15-5.875 GHz, Six-feed, 12/11 dBi, 27/30 deg, panel with reverse polarity type-N plug connector

WS-AO-DX10055                             Outdoor, 2.4-2.5/5.15-5.875 GHz, Six-feed, 10/6 dBi, 55 deg, panel with reverse polarity type-N plug connector

I would choose the model WS-AO-DS05360 because it best fits to the currently installed access points with 3dBi omni antennae.

Since the new access point is 3x3:3 and should use both frequency bands I would install 6 of these antennae.

My “problem” with this topic is the huge number of antennae and how to mount them. One antenna is around 90cm in length and the vendor only provides a mount kit for pole mount. Can someone provide a picture of an access point mounted with several huge antennae indoors?

What’s your opinion to use only one or two antennae per radio instead of three? I know that multiple antennas will provide additional throughput, reliability and range.

For this project high throughput isn’t necessary, the primary factors are high reliability and low to medium cost.

What is your recommendation on the number of antennas? Indoor (Multipath) vs. Outdoor?

Another access point model isn’t an option, therefore another solution would be to perform a site survey and use sector/panel antennae instead of the large omni antennae.

I'm very interested in your recommendations and feedback to this topic!

Thanks in advance!

How is a 5dB antenna close to a 4dB antenna? Given the same input power that 2dB difference is nearly double the EIRP.

You don't say which access point will be used? Applications on the network.

Having 2 or 3 antennas depending on the ap will help meet one of you criteria namely high reliability. Your signals will be more resilient with the correct installation.

A site survey is a must, what about interferers? Were the as in the optimal position when they were first installed. 

I think the point was that the nearest to the 3 dB provided by the vendor was 5 dB. 5 dB is about 63% more power than 3 dB, but this can, in part, be addressed through output power adjustment.

Tom

Indeed we can address that with output power, it seems like an expensive antenna when a 3dB dipole is about $20.

I couldn't see all antennas on the Extreme site and it would be good to know which ap was being deployed.

Yes, and I emphasized that it could be addressed "in part" because different antennas have different coverage patterns in a given space. We have no idea what this space is. Most likely, the added benefit of MIMO will address any coverage concerns once the output power is adjusted, but it's hard to say for certain without more details.

Tom

Hi pingu, hi Tom,

thank you for the fast replys!

i'm aware that the 5dBi antenna will provide more horizontal and less vertical coverage, but that should be ok. 

The planned AP type is Extreme.Networks/Enterasys AP3767e. I posted all related anntenae for this AP.