Microperforated absorbers (MPA) are a well-established technology for attenuating sound in flow carrying ducts. MPAs usually consist of a microperforated panel (MPP) in combination with a cavity as back volume. The damping maxima of MPAs occur in the range of their resonant frequencies and the effect is narrowband compared to porous or fibrous absorbers. which damp broadband at high f... https://allfixelectricales.shop/product-category/uhf-vhf-antenna-diplexor/