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nRF24l01+ Through Concrete

RAB

We have developed and certified a module which uses the nRF24l01+. We spent a good amount of time tuning the antenna circuitry which has resulted in very good range... in open space. The primary transmitter is located in a plastic enclosure and uses a ceramic chip antenna. The primary receiver is located in a metal enclosure (yeah I know metal is not good etc...but we still measured good field strength) with a sizable plexiglass window. The primary receiver uses a 1/4 wave external antenna with 2.1 dBi of gain. For the majority of the installations everything is running extremely well however more and more units are being installed on opposite sides of thick concrete walls. Any ideas about increasing the penetration through these concrete walls, without too much modification of the antenna circuitry.

Just to get it out there, we have also setup a primary receiver outside of the metal enclosure so that only the concrete wall was the loss path. This did help but it did not fix the issue.

Thanks

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    My home was built in two separate phases (bear with me here). Because of that, I have an original concrete block foundation and then an additional foundation has been added on one side. My lab and office are located in the "new" part below grade, and as such it is surrounded by the concrete foundation.

    I'm using BLE (nRF51822) for my application and I can't get any signal through even this relatively porous foundation. As the previous poster pointed out, there will be some attenuation due to the rebar, but even the concrete itself introduces propagation issues for 2.4GHz. I believe your average concrete wall or floor is generally considered to introduce ~30db of attenuation.

    These concrete walls won't actually be a Faraday cage as I doubt the rebar is grounded and the mesh size would need to be much, much smaller than found in concrete work (unless you happen to have rebar that has a 1/4" mesh). But as I mentioned, it'll add to attenuation and introduce scatter too.

    For an example of a true Faraday cage in the mid-Ghzs, go to your kitchen and look at your microwave oven :)

    Cheers,

    -m

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    My home was built in two separate phases (bear with me here). Because of that, I have an original concrete block foundation and then an additional foundation has been added on one side. My lab and office are located in the "new" part below grade, and as such it is surrounded by the concrete foundation.

    I'm using BLE (nRF51822) for my application and I can't get any signal through even this relatively porous foundation. As the previous poster pointed out, there will be some attenuation due to the rebar, but even the concrete itself introduces propagation issues for 2.4GHz. I believe your average concrete wall or floor is generally considered to introduce ~30db of attenuation.

    These concrete walls won't actually be a Faraday cage as I doubt the rebar is grounded and the mesh size would need to be much, much smaller than found in concrete work (unless you happen to have rebar that has a 1/4" mesh). But as I mentioned, it'll add to attenuation and introduce scatter too.

    For an example of a true Faraday cage in the mid-Ghzs, go to your kitchen and look at your microwave oven :)

    Cheers,

    -m

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