Millimetre wave propagation through vegetation

Propagation of electromagnetic waves through canopies of wood are of interest for he choice of operating frequencies for microwave based sensors of different kind. It is known that in general the propagation properties become worse with higher frequency. Especially the upper millimeterwave bands are severely attenuated by leaves. Measurements were conducted during a period in spring on a transmission path through an apple tree. The measurement period covered states of the tree ranging from leave-less over blooming to fully developed leaves on the branches. Three frequency bands were covered, namely 10 GHz, 35 GHz and 94 GHz. To allow a concise judgment of the data, meteorological measurements were done in parallel.