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A designer really wants their access points visually hidden behind aluminum louvers. So I'm looking for info on the attenuation of aluminum. Can anybody help point me in the right direction? Thanks!

All metal (like aluminum) will block RF in the power range available for Wi-Fi. Even a thin foil (like mirror finish on plastic) will kill Wi-Fi. Minuscule amounts of metal like tinted/thermal glass or chicken wire holding stucco in the walls will cause problems. Metal reflects radio energy. In your case your could even damage your APs inside the aluminum covers.

You may just as well put all lamps behind aluminum barriers. You need to educate your designer or hire a competent one. A professional designer should acknowledge the laws of physics.

Agree with Petri, but I also know that reliable transmission will depend on the Mesh size of the screen involved.

Typically, you will find texts which recommend a mesh spacing of 1/20 the wavelength, or smaller, to create an effective RF screen.   But I have found signals getting through "holes" this size.   

There is a saying in RF, about enclosures - "if it leaks water, it will leak RF".

There are many factors involved besides mesh size, including the grounding on the screen, angles of arrival, and others.

Probably the biggest effects would be on elevated enclosure temperature, and the antenna pattern.   It won't look anything like what the manufacturer says it will be !

There are many ceiling, wall, and floor antenna possibilities that are very unobtrusive.    Some replace existing panels, light switch covers, and floor tiles.  I suggest you look at Ventev's designs, and I'm sure you can find others that your designer will not a have a problem with.    Give them a call.

Here are some ideas - and they have more available:

http://www.ventevinfra.com/aesthetics/

Hey there Petri. I stay way from metal louvers/ barriers altogether. Metal is not RF friendly at all pretty much everywhere (expect db loss depending on thickness +10-15db). I am at Disneyland here in in Anaheim and they want to hide EVERYTHING especially behind louvers and such.

We always replace metal with FRP, fiberglass, plastic (HDPE) or similar RF Friendly material. You also want to ensure that antennas behind louvers have enough spacing between metal studs as well to avoid chopping signal laterally off side of antennas and enough vertical clearance above parapets louver openings. Hope this helps. Please reach out if need more info as we have the most louvers of anyone!! We have a castle afterall!

It seems I can find quite a bit of information from, e.g. Strongwell on FRP, but when it comes to its use on louvers, it gets hard to find details related to RF.

For example, for pultruded louvers, the  Peabody site says "FRP shapes are needed in some cases to meet the structural requirements of the site and perform better than conventional building materials such as steel and wood. However, FRP pultruded shapes should be used as little as possible and avoid having them directly in front of the antennas."  Other sites mention "tuning" FRP radomes depending on the frequency band(s) in use.

I am  familiar with the effects that plastic composition on Wi-Fi performance, especially range, on hand held and table top products.  However I have little experience with louvers.

What can you say about louvers, their spacing, materials,and frequency bands in light of the Peabody recommendations.   I assume you are also running some PtP scenarios.   Have you found other problems in that area caused by any of the plastic materials ?   Do you see any differences between RF bands?

Thanks very much.

Being here at Disneyland we have all kinds of louvers, vents, and radomes that have been built for concealing antennas. That said, most of our stuff is fabricated to spec so we have some control over ensuring thickness (not > than .5" or less). As for signal penetration, most has been good behind FRP exceptions are louvers where louver was replaced but there was Bird Mesh (inhibits building nests behind louvers) we did not know about. Most of our plastics, FRP experience has been good (RSSI -60 dBm @ 35-40') from antenna behind FRP.

As we go deeper into deploying more AP's around the resort we are having to become more and more creative with the creative people as to how stuff gets covered relative to the desired RF coverage are and performance specifications for the end users in those areas.