An equivalent-medium model is developed for vegetation media to relate
the propagation constant gamma, associated with propagation of the me
an field through a vegetation canopy, to the geometrical and dielectri
c parameters of the canopy constituents at high frequencies. The model
is intended for media containing vertical dielectric cylinders, repre
senting the stalks, and randomly oriented, arbitrary shaped thin diele
ctric disks, representing the leaves. The formulation accounts for abs
orption and scattering losses by both stalks and leaves. A resistive s
heet model in conjunction with the physical optics approximation is us
ed to model scattering by the canopy leaves, which is valid when the l
eaf dimensions are larger than a wavelength. The model is found to be
in good agreement with experimental results at 10.2 GHz. The experimen
tal component of the study included measurements of the attenuation lo
ss for horizontally polarized and vertically polarized waves transmitt
ed through a fully grown corn canopy. The measurements were made at in
cidence angles of 20-degrees, 40-degrees, 60-degrees, and 90-degrees r
elative to normal incidence. The proposed model is suitable for cornli
ke canopies, provided the leaves are larger than lambda in size.