The facts about Flat Sheet Absorbers
As well as being a commercial supplier we also like to share our knowledge for people who want to know. We have put together unbiased fact sheets for each of the products we supply.
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An unbiased data sheet
Flat sheet absorbers are used in products to prevent emission resonances and to suppress EMC (electromagnetic compatibility) problems.
If you consider the return loss in free space then the absorbing properties can be defined as return loss, that is, the loss of signal when a single reflection is calculated, the behaviour of the same material inside a resonant cavity can be many times more effective because the same material is suppressing multi-reflections from within the cavity/product/apparatus.
The absolute effect of thin sheet absorbers in a resonant cavity is very difficult to pre-calculate and so the empiric method of development is normally used.
The material is normally Polyurethane foam doped with stabilized carbon combined to make an absorber thin and flexible enough for cutting, sticking, folding etc
The thickness and carbon doping can be ‘tuned’ to be optimised at a particular frequency This type of material can be die cut, folded, glued into position.
An acrylic coating wash or similar (by the absorber manufacturer) guarantees that carbon from the absorber cannot contaminate and other part of the equipment.
