RF Signal Loss in Penetrating a Building

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Building Penetration Loss-1

SOURCE:
International Telecommunication Union (ITU)'s RECOMMENDATION ITU-R P.679-2, 1999

Representative UHF signal attenuation observed within rooms located near an exterior wall in timber-framed private homes is summarized in Table 1. For interior rooms, 0.6 dB must be added to the tabulated values. For timber framed buildings the attenuation shows little variation with weather or path elevation angle but, as the table illustrates, there is a systematic variation with frequency, construction materials, insulation and position within the structure. Some aluminium-backed insulating and construction materials contribute up to 20 dB of loss.





Building Penetration Loss -2

SOURCE: Communications Research Centre, Industry Canada: Paper dated April 2011.

Apparently conflicting results have been reported in the literature concerning the dependence of building penetration loss on frequency. While several researchers have reported measurements indicating that building penetration loss decreases with increasing frequency in the VHF and UHF range, results by other researchers suggest the opposite, or that there is no significant dependence on frequency at all.

It has been noted that the frequency dependence of penetration loss appears to be strongly dependent on the type of building construction.

For residential buildings, which are typically constructed from non-metallic building materials such as wood, cinder block, brick veneer and glass, penetration loss has been found to be relatively low and to increase with increasing frequency. This observation is supported by results of laboratory measurements on a variety of common building materials, which show that, while propagation losses through most building materials are almost the same at 2.4 and 5 GHz, red brick and cinder block are notable exceptions; losses associated with these materials are 10.1 and 3.6 dB higher, respectively, at the higher frequency.

Industrial and commercial buildings, on the other hand, are often of steel-framed construction, and the corresponding predominant building materials are reinforced concrete, steel, and aluminum; loss through these materials is relatively much higher, and the dominant penetration mode is through slots such as windows and other frame openings, or even through grid openings in in steel-reinforced concrete slabs. Losses associated with propagation through slots tend to be strongly frequency-selective, and overall decrease with increasing frequency, as the slot dimensions become larger in terms of the wavelength.




Fig 1 - Measuredbuilding penetration loss versus frequency, for residential buildings.





Building Penetration Loss -3

Source: COST 231 , 1999, a project of EUROCOST "The European Co-operative for Scientific and Technical research" or "Coopération européenne dans le domaine de la recherche Scientifique et Technique", which is a European Union Forum for cooperative scientific research.