Omni directional antenna orientiation?

[TomVolpe]

I’m deploying model 66 and 74 AP’s with two pairs of omni directional antennas. They will be mounted to a 35 to 40 feet ceiling in our warehouse. Are the antennas oriented to be parallel to the floor or perpendicular?  

[BrechtSchamp]

Perpendicular to the floor.

[Chadluby]

Hey my friend it looks like you're quite familiar with what's going on with antennas. I just bought a 16 DBI antenna and mounted it on my roof but it leans in because of the amount I had to use about 6 in from the top to the bottom not very noticeable but definitely leaning. I am currently trying to join the helium network which mines cryptocurrency over radio waves and I haven't been able to connect to another hotspot in several days and I'm curious whether this little bit of lean maybe shooting my radio waves into the ground on one side and over the hot spots on the other.? I hope you can help me with this and I appreciate you trying to help me.

[GIdenJoe]

16 dBi is not omni directional but highly directional so you better make sure that antenna is aligned properly. With these kinds of gains you probably have less than 30 degrees before you lose half of your signal.

[GIdenJoe]

Did you do a survey for that?
That ceiling height is alot for omni antennas.

[TomVolpe]

No survey done but an educated guess. We had Nortel AP's and purchased Meraki's to replace them. We put them in the same locations because of the cabling was there and the foot print of coverage had not changed.   We recently have expanded the coverage footprint and I have engaged an installation crew to pull new cables and mount the AP's. It was brought to my attention from the guy mounting them that the Meraki's AP's he installed over the years that they were mounted facing down and the antennas facing parallel to the floor. My current AP's are all installed 35 feet up with the 2.4 antenna's pointing straight up and the 5 ghz antennas pointing straight down. The Model 66's have been in place like this for 6 years. They only are used for handheld scanners in the warehouse so their bandwidth requirements was small. 

I'm kind of stuck on what to do. I opened a support ticket with Meraki today and they said to mount them parallel to the floor.

I really want to know what is optimum orientation

[GIdenJoe]

Well I don't have my Ekahau kit at home with me but it has to stay at the office.

Firstly your scanners: do they connect to 2.4 or 5?
What channels do they support?
Is your current Wi-Fi designed for 2.4 or 5?

If you're using OMNI's on the MR74 AP's I have to assume they are MA-ANT-20.
They are quite high in gain especially in the 5 GHz band and judging from the antenna patterns you could have issues if you place them wrong.

Normally you must place omni's perpendicular to the floor because the signal is spread more in the horizontal axis and you lose alot of strength vertically.  In normal cases this is no problem but in this case your AP's will be mounted quite high which means your signal will have much lower power on the ground causing potential coverage holes.

If you would mount them parallel to the floor then you will send alot of signal to the floor and in one horizontal axis but quite little in the other.  Once again judging from the antenna plot (https://meraki.cisco.com/lib/pdf/meraki_datasheet_antenna_omni_4_7dBi.pdf) if you point the antennas towards the racks and not down the isle you should have the best results.  Because you would send the least power to the racks and most down the isle.

You could still end up short though.  If you need to test this.  Mount an AP temporarily and make sure it does not send out more than 12 dBm of power since that is the max alot of scanners will send back to the AP and do a few tests below the AP and near the edge to where the previous AP could reach.

Else if you know someone with ekahau, ask them to do a quick test with your size of floorplan to see which orientation would have been best however always perform a site survey and never assume another vendors AP's will give the same results as others.  Antennas vary wildly.

[TomVolpe]

I did a crude survey 6 years ago after we swapped the Nortels for Meraki. I used InSSIDer. I walked the floor with my laptop and an accurate floor plan. It showed rows and columns every 20 feet. I stood at the intersection and recorded the highest 2.4 signal at that location. I seem to recall 38 to 60 db was the threshold of 'excellent" signal and 88 was high end of weak.  The majority of the signals recorded were 55 to 72 db.  There were some 'dead' spots then  but I know were they are and will put model 74 with MA-ANT-20. to fill in.

I still have to support both 2.4 and 5 but scanners (15 to 18) will use 2.4 on the scanners.

I have 18 Model 66 and 74 AP's to cover 250,000 sqft. 

I suspect I'm ok with the orientation of the AP's. I can get them lowered if that would improve coverage. Other that the Model 66's needing rebooted twice a month they have not been a problem.