Vegetation attenuation: modelling and measurements at millimetric frequencies

Several measurements have been made to determine the extent of attenuation of millimetre-wave signals when propagated through vegetation. Methods for predicting such attenuation exist, but are either deterministic in form and therefore complex to implement completely empirical and take no account measurement geometry. A new semi-empirical model is presented which is based on measurements of vegetation attenuation presented previously, and has some account of the measurement geometry. This model is compared with measured data and is shown to give considerably better agreement than that given by previous models. Further indoor measurements (at 35, 37.5 and 4 GHz) have been made of the attenuation through three types of trees have also been made and the results are presented.