Thesis - Leigh Moody.pdf - Bad Request - Cranfield University

Chapter 3 / Sensors / Radar
_ _
This comprises from left to right, atmospheric, squint, beam broadening,
and miscellaneous losses. For the missile, taking into account those losses
which are applicable only in the receiving direction,
L : = L ⋅ L ⋅ L ⋅ L
F
3.8-12
A
S
B
M
Equation 3.8-43
The receiver, noise factor and ohmic losses have already been accounted for
in the receiver noise temperature. The one-way clear air atmospheric
transmission loss in dB for ranges of up to 30 km, and elevation angles
[0°,60°] is shown in Figure 3-40. If the range or elevation exceed these
limits the bounds are applied. The atmospheric losses are modelled using a
B-spline surface fit the spline coefficients (Cij) for which are listed in Table
3-16.
a
ij
i
TB
( P ) ⋅ N ( )
L : = C ⋅ M
Θ
o,
t
j
A
Equation 3.8-44
Table 3-16 : Spline Coefficients and Knots for Atmospheric Loss ( La )
λ := ( ( 1_
000 ) 12 _ 000 ( 60 _ 000 ) ) µ := ( ( 0 ) 20 ( 60 ) )
i
1x4
C(1,1) 0.020137 C(2,4) 0.081786 C(4,2) 0.461584
C(1,2) 0.019144 C(2,5) 0.080725 C(4,3) 0.103283
C(1,3) 0.015621 C(3,1) 0.484391 C(4,4) 0.124817
C(1,4) 0.017414 C(3,2) 0.419847 C(4,5) 0.098113
C(1,5) 0.016732 C(3,3) 0.201075 C(5,1) 1.150142
C(2,1) 0.091582 C(3,4) 0.162224 C(5,2) 0.461883
C(2,2) 0.091696 C(3,5) 0.131589 C(5,3) 0.137247
C(2,3) 0.094576 C(4,1) 0.870763 C(5,4) 0.133738
1x4
j
1x4
1x4
C(5,5) 0.112892
The beam widens as the target moves off the detector boresight resulting in
a squint loss that depends on the cosine of the off-boresight angle,
L : = sec ξ
S
TB
TD
Equation 3.8-45
Beam broadening losses depend on the angle from the beam to target LOS,
L
B
: =
⎛
⎜ ⎛
6 ⋅ ⎜
⎜ ⎜
⎝ ⎝ ξ
BW
T
ΘTB
⋅ sec Θ
T
TB
⎞
⎟
⎠
2
⎛
+ ⎜
⎝ ξ
BW
T
ΨTB
⋅ sec Ψ
T
TB
⎞
⎟
⎠
2
⎞
⎟
⎟
⎠
Equation 3.8-46