Site shielding reduction due to transmission through buildings in a city centre environment

A theoretical model has been presented whereby the field strength in the shadow of parallel screens containing rectangular apertures may be predicted. This has been proposed as a basis for predicting signal levels transmitted through buildings whose surfaces contain rectangular glass windows. Predictions based on this model suggest that for typical building dimensions, high levels of transmission through the building may be expected, particularly at frequencies above 3 GHz. The model does not, however, consider any obstructions to propagation contained within the building. In order to obtain relevant data, a measurement programme was conducted, at a frequency of 11.2 GHz, using real buildings as the obstacle. This revealed that, although high levels were recorded in the shadow of a narrow building without any internal obstructions, all typical office buildings investigated provided protection of at least 20 dB. This suggests that, although buildings may not form a perfectly absorbing obstacle on an interference path, they normally will afford useful amounts of protection.