Building materials impact RF signals

Article By : John Dunn

Sheet metal incorporated into a building's structure can cause problems regarding the use of RF signals.

Sheet metal incorporated into a building’s structure can cause problems regarding the use of radio frequency (RF) signals.

I once knew a man whose house roof had been constructed using copper lining under the shingles. It was a very old house located somewhere in Queens near where I grew up and that roof was durable with a “capital D.” However, when he took up amateur radio (which was how I met him) and we tried to set up a “40-meter dipole” antenna for him, we could not get the standing wave ratio of that dipole to be any lower that three or four to one. It was a problem we were never able to solve.

More recently, I have attended quite a few lectures at Planting Fields Arboretum in Upper Brookville, NY in a building called the Conference Center, two views of which are shown below.

Conference Center at Planting Fields Arboretum

Smartphones do NOT work inside this building. One has to come outside to make any phone calls or to look anything up online. I took a close look at the building exterior one day and so far as I could see, the entire structure seems to be completely encased in aluminum siding. From what I can tell, the result is a zone of silence, a dead zone into which RF does not penetrate and from which RF does not emerge. I can imagine this building one day being the site of an EMI test facility.

The caveat is that if you are hired into any project involving RF, don’t forget to check up on how the surrounding structures are built, or will be built. You don’t need any unpleasant surprises.

John Dunn is an electronics consultant, and a graduate of The Polytechnic Institute of Brooklyn (BSEE) and of New York University (MSEE).

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