Attenuation Measurements of Materials Used in Construction of Buildings

Abstract

In the article research methodology and measuring position for determining at- tenuation of materials used for building structures have been described. The discussed research methodology is based on microwave measuring set on the basis of coaxial line guaranteeing large bandwidth of realized measurements. In the article selected samples of materials used for build- ing structures have been characterized as well as attenuation results of those materials have been presented. Attenuation of walls, ceilings or other building barriers depends | among other things | on per- mittivity of material the wall is made of, frequency of incident radiation and wall thickness. In order to determine attenuation of electromagnetic waves by wall, each wall should be measured individu- ally to deflne what level of electromagnetic fleld intensity is attenuated by such a barrier. In order to determine attenuation of materials used for building structures it is necessary to perform ana- lytical calculations of electric fleld attenuation or make a direct measurement on a natural sample of a particular material. For analytical calculation of electromagnetic fleld attenuation by shielding material it is necessary to determine electric and magnetic values of material a particular structural material is made of. Parameters which deflne the above mentioned properties are respectively per- mittivity and magnetic permeability of tested material. Due to the fact that building materials, particularly those based on natural raw materials(concrete, brick, plaster), are characterized by sel- dom repeatable composition, the only method of estimating their electric and magnetic properties is conducting laboratory measurements with the use of natural samples (3,4,7,8,10{12,14). 2. MICROWAVE MEASURING SET FOR ATTENUATION TESTS BASED ON COAXIAL LINE For conducting attenuation tests of materials used for building structures a microwave measuring set has been designed. With the use of the above mentioned set we can make measurement and determine values of combined coe-cients of dispersion matrices which next can be used for calcula- tion of attenuation coe-cients and absorption of particular shielding material. The measuring set in current conflguration makes measurements within the frequency range from 50MHz to 6GHz possible. Band limitations for this set are caused by the set structure on the basis of coaxial line, possessed measuring equipment and measuring software (2,5,6,9,13).