Biomedical Engineering Reference
In-Depth Information
Figure 11.14
Experimentally measured Fourier-Hankel transforms of far-
field scattered radiation by (a) GA spiral and (b)
τ
spiral, respectively,
summedovertheradialwavenumber
k
r
.Thenumbersinthefiguresindicate
the azimuthal Bessel order of the corresponding FHD peaks. Analytically
calculated Fourier-Hankel transforms of far-field scattered radiation by (c)
GA spiral and (d)
τ
spiral.
azimuthal dependence is accomplished through FHD according to
the Eq. (11.5). We recall that in this decomposition, the
m
-th order
function carries OAM with azimuthal number
m
, accommodating
both positiveand negativeinteger values for
m
.
In Figs. 11.14 and 11.15, the summed FHD of the calculated
andexperimentallymeasuredfar-fieldradiationfromthefabricated
spirals are shown. Here, we have summed the
f
(
m
,
k
r
)overthe
radial wavevectors
k
r
as we are primarily concerned with the
azimuthal component of the field. We should notice in Figs. 11.14
and 11.15 that the azimuthal spectra exhibits a number of peaks
