Graphics Programs Reference
In-Depth Information
Example:
Compute the power aperture product corresponding to the radar that has the
following parameters: Scan time
, Noise figure
, losses
T
sc
=
2sec
F
=
8
dB
L
=
6
dB
, search volume
Ω
=
7.4
steradians
, range of interest is
R
=
75
Km
,
and the required SNR is
20
dB
. Assume that
T
e
=
290
Kelvin
and
3.162
m
2
σ
=
.
Solution:
Note that corresponds to a search sector that is three
fourths of a hemisphere. Thus, using Eq. (1.61) we conclude that
Ω
=
7.4
steradians
θ
a
=
180°
and
. Using the MATLAB function Ðpower_aperture.mÑ with the fol-
θ
e
=
135°
lowing syntax:
PAP = power_aperture(20, 2, 3.162, 75e3, 290, 8, 6, 180, 135)
we compute the power aperture product as 36.7 dB.
1.6.1. Mini Design Case Study 1.1
Problem Statement:
Design a ground based radar that is capable of detecting aircraft and mis-
siles at 10 Km and 2 Km altitudes, respectively. The maximum detection range
for either target type is 60 Km. Assume that an aircraft average RCS is 6 dBsm,
and that a missile average RCS is -10 dBsm. The radar azimuth and elevation
search extents are respectively and . The required scan
rate is 2 seconds and the range resolution is 150 meters. Assume a noise figure
F = 8 dB, and total receiver noise L = 10 dB. Use a fan beam with azimuth
beamwidth less than 3 degrees. The SNR is 15 dB.
Θ
A
=
360°
Θ
E
=
10°
A Design:
The range resolution requirement is ; thus by using Eq. (1.8) we
calculate the required pulsewidth , or equivalently require the
bandwidth . The statement of the problem lends itself to radar siz-
ing in terms of power aperture product. For this purpose, one must first com-
pute the maximum search volume at the detection range that satisfies the
design requirements. The radar search volume is
∆
R
=
150
m
τ
=
1µsec
B
=
1
MHz
Θ
A
Θ
E
57.296
360
×
57.296
10
Ω
=
-----------------------
=
-----------------------
=
1 . 0 9 7
steradians
(1.73)
)
2
)
2
(
(
At this point, the designer is ready to use the radar search equation (Eq.
(1.67)) to compute the power aperture product. For this purpose, one can mod-
Search WWH ::
Custom Search