Calculating RF attenuation for various wall/ceiling types

[ThomasBates]

Hello,

I am needing to calculate RF attenuation for various wall/ceiling types. Is there a resource that I can use for figuring this out? Something such as agreed upon RF attenuation values for various material types? The image below is an example of a wall/ceiling types that I am needing to calculate attenuation for.

Thanks!

[DCooper]

Do you have a spectrum analyzer or planning tool? We use Ekahau here at Cisco-Meraki. Most of these tools have different values pre-built into them if your doing a predictive site survey.

[ThomasBates]

I'm using NetScout's AirMagnet (but I've heard great things about Ekahau).

Yes there are pre-calculated wall types included in AirMagnet but I'm dealing with rather specific acoustical wall types. So I need to create custom wall types. I can make an educated guess based on pre-built wall types but I need some assurance that my educated guess is correct. This is for a space that has not yet been built so I do not have the option to go onsite to measure the attenuation.

[DCooper]

There is a way to build custom types in Ekahau but the problem still exists. You can't know the figures unless an active site survey has been completed. What exactly is your concern where you couldn't estimate this and pass the assumption onto the customer or add in 10-15% overage to cover for the unknown?

[ThomasBates]

The question would be then can I estimate this within 10-15% accuracy? For example the built-in wall "Dry Wall" has a 4dB attenuation. Is it therefore safe to assume that each layer of dry wall accounts for 2dB loss? So an acoustic wall with 5 total layers of drywall would account for a total of 10dB loss? Is that a safe assumption or not? How much attentualtion is the fiberglass insulation introducing? So I'm looking for information on which I can safely base my assumptions. Can anybody point me toward any such resource?

[PhilipDAth]

If sounds like you need to get a sample wall built, or perhaps a small scale room, to take some measurements.

[ThomasBates]

Yes that would certainly be one way of doing it. It would of course be a rather expensive and time consuming solution...

[PhilipDAth]

The cost of getting the correct answer without guessing perhaps.

Getting 5 sheets of dry wall - that are going to have to be purchased anyway - doesn't sound expensive to me.

[Uberseehandel]

Better to reschedule AP deployment planning until later in the project.

[ThomasBates]

Yeah, that would be nice. But we need to get them a fairly accurate assessment before construction begins.

[DCooper]

What are you designing this RF environment for? BLE, RFID?

[ThomasBates]

Normal old internet access. But it's for a music school so there are many less common acoustic wall types that are likely to have a large impact on signal strength.

[Uberseehandel]

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@ThomasBates wrote:

Hello,

I am needing to calculate RF attenuation for various wall/ceiling types.

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Theoretical figures are just that.

Wait until you come across foil lined plasterboard. It is cheaper, more accurate and more useful to use something like Akamai. 

[ThomasBates]

Hi Robin. Can you please elaborate on "use something like Akamai"? I'm looking into what they do now. I wasn't familiar with that company.

[Uberseehandel]

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@ThomasBates wrote:
Hi Robin. Can you please elaborate on "use something like Akamai"? I'm looking into what they do now. I wasn't familiar with that company.

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Thomas

I most definitely did NOT mean Akamai, I intended to write Ekahau - too many warm fuzzy names ! Entirely my fault.  

It is appropriate to use in the planning stages as well as post installation to iron out problems and adjust AP locations. Plenty of documentation on site. They even have a free version.

Sorry about the confusion.

[RJCanis]

@ThomasBates,  Did you ever get an answer to your question?  I too am building a wall exactly like yours and was wondering if you ever got the right information.  I would have to even think that the air gap would also make things a little interesting.

Thanks in advance!