3.4 Scattering Cross Section of Simple Point Targets
37
Fig. 3.14 Energy scattering
function of fine wire
equals to its limiting value. RCS minimum approximately corresponds to condition
l = (n + 0.35)λ. For cylinders, the radius of which lies within (0.01…0.5)λ limits
and length within (0.05…5)λ limits λ; scattering characteristics at field polarization
along cylinder axis are the most complicated since here two resonant sizes exist
simultaneously. Information for this case is almost absent in the published literature.
For cylinders, the radius of which lays within (0.01…0.5)λ limits, and length
exceeds 0.5λ; a relation A/
2π
λ
rl
2
as a function 2r/λ is expressed in Fig. 3.15.
Infinite cone RCS In general case, a rigorous problem solution on scattering of
electromagnetic waves on a cone of finite size has not been obtained yet. Let us find,
within ray-optical approximation, the RCS values for a cone of H finite height with
angle near an apex 2α at its observing along an axis.
We use formula (3.21) and Fig. 3.16 for calculations, from where we can see that
D =
x 2 + y 2 ctgα.
By transferring to polar coordinates, we obtain:
A =
4π
λ 2
2π
∫
0
dy
htgα
∫
0
e
−2 jkrctgα dr
2
.
(3.38)
Direct calculation result in:
A =
λ
2 tg
4
α
16π
1 + 4k
2 H
2 e
−4β H
+ 4k He
−2β H cos k H
,
(3.39)
Fig. 3.15 Energy scattering
function of disk
37
Fig. 3.14 Energy scattering
function of fine wire
equals to its limiting value. RCS minimum approximately corresponds to condition
l = (n + 0.35)λ. For cylinders, the radius of which lies within (0.01…0.5)λ limits
and length within (0.05…5)λ limits λ; scattering characteristics at field polarization
along cylinder axis are the most complicated since here two resonant sizes exist
simultaneously. Information for this case is almost absent in the published literature.
For cylinders, the radius of which lays within (0.01…0.5)λ limits, and length
exceeds 0.5λ; a relation A/
2π
λ
rl
2
as a function 2r/λ is expressed in Fig. 3.15.
Infinite cone RCS In general case, a rigorous problem solution on scattering of
electromagnetic waves on a cone of finite size has not been obtained yet. Let us find,
within ray-optical approximation, the RCS values for a cone of H finite height with
angle near an apex 2α at its observing along an axis.
We use formula (3.21) and Fig. 3.16 for calculations, from where we can see that
D =
x 2 + y 2 ctgα.
By transferring to polar coordinates, we obtain:
A =
4π
λ 2
2π
∫
0
dy
htgα
∫
0
e
−2 jkrctgα dr
2
.
(3.38)
Direct calculation result in:
A =
λ
2 tg
4
α
16π
1 + 4k
2 H
2 e
−4β H
+ 4k He
−2β H cos k H
,
(3.39)
Fig. 3.15 Energy scattering
function of disk