A Wide-Beam Scanning Mode for Near-Space Passive SARs
Table 1
Parameters employed in the simulation.
Parameters
TerraSAR-X
An X-band receiver
Envisat
A C-band receiver
TerraSAR-L
A L-band receiver
Altitude (km)
515
20
800
20
645
20
Velocity (km/s)
7.6
0.005
7.45
0.005
7.53
0.005
Incidence angle (°)
20–45
30–50
15–45
30–55
20–45
40–50
Carrier frequency (GHz)
9.65
9.65
5.331
5.331
1.2575
1.2575
Peak power (kw)
2.26
—
2.3
—
4
—
Loss1 (dB)
2/5
3
2/5
3
2/5
3
Aperture efficiency
0.7
0.7
0.7
0.7
0.7
0.7
normalized radar cross section (dB)
−20
−20
−20
−20
−30
−30
Pulse width (μs)
45
—
25
—
35
—
Noise figure (dB)
5
5
5
5
5
5
Noise temperature (K)
300
300
300
300
300
300
Bandwidth (MHz)
150
150
16
16
85
85
Beamwidth ELV (°)
2.3
18.6
2.2
12.7
4.2
21.2
Beamwidth Az2 (°)
0.33
—
0.29
—
1.1
—
Maximum steering angle (°)
—
30
—
30
—
40
PRF (KHz)
4
4
2
2
2
2
Operational PRF range (KHz)
3–6.5
—
1.6–2.5
—
1.5–3
—
1The left of the slash sign is the transmit loss for the near-space passive SAR; the right is the total loss for the monostatic spaceborne SAR.
2The azimuth beamwidth of the receiver is calculated by (4).
