AP 1140 Interference

Question

Hi,
We have AIR-LAP1141N-E-K9, that will be installed above false ceiling made of "perforated aluminum" with 1mm thickness with 17% open slotted surface.
What would be the level of interference and signal loss?
Many thanks,
Yazeed

Answer 1

Yazeed,
The widespread experience among wireless engineers is pretty much what Leo is saying--metal screens and panels are a wireless killer.
Perforated aluminum ceiling panels are going to severely degrade your signal. At 17% open space in a 1mm thick sheet, you have mostly metal with a bunch of small holes or slots. Look at the door of your microwave oven. There is probably 40% to 50% open space on the door grille, and yet an insignificant amount of microwave energy escapes the oven.
Actual energy loss is a function of size and shape of the openings, the wireless frequency, panel thickness, material composition, radiator distance from the panel, etc., which is why a wireless survey of the actual environment is of critical importance when you're dealing with metal in spaces where you want to deploy WiFi.
For planning purposes, you should assume that you cannot mount your 1141 AP above the aluminum ceiling panels unless all you want to do is heat the airspace there get nothing else out of it. I recommend that you consider alternative solutions such as mounting your APs below the ceiling plane or using patch antennas mounted on the (hopfully not metal) walls and attached to 1260, 3502e or 3602e series APs.
If you are in a position where you need to mathematically justify this rationale and you want to get a rough numerical sense of what you're up against, google around for an RF shielding effectiveness online calculator. Clemson has a good one (with aluminum as a selectable material) and there are a few others.
Justin