💡 SAR Fundamentals

SAR synthesises a large virtual antenna by coherently recording radar echoes as the platform moves. The result: high-resolution 2-D imagery, day/night, all-weather.

ρaz = D / 2

Azimuth resolution = half antenna length — smaller antenna → finer resolution!

ρrng = c / 2B

Range resolution set by chirp bandwidth B only.

Lsyn = λR / D

Synthetic aperture grows with range — resolution stays constant.

Controls
Altitude (H)500 km
Antenna Length (D)4 m
Chirp Bandwidth (B)150 MHz
Frequency Band
L
S
C
X
Ku
Results
Wavelength (λ)5.6 cm
Synth. Aperture (L)7.0 km
Integration Time0.9 s
SAR Az. Resolution2.0 m
Range Resolution1.0 m
Real Aperture Az. Res.7.0 km
SAR improvement factor3500×
SIDE VIEW — PROFILE
TOP-DOWN VIEW — PLANNADIR
RANGE CHIRP (LFM)WAVEFORM
DOPPLER HISTORYAZIMUTH
2.0
metres
Az. Res.
1.0
metres
Range Res.
7.0
km
Synth. Aperture
3500×
vs real aperture
SAR Gain
📡 Operating Modes
➡️
Stripmap
↕️
ScanSAR
🔦
Spotlight
🔄
TOPS
🚢
ISAR
🌐
InSAR
Geometry Parameters
Altitude (H)514 km
Pulse Duration (τ)30 μs
PRF1600 Hz
Look Angle θ
θ (look angle)23°
θ_min (nadir)
7.7°
H / (H + cτ/2)
θ_min (PRF)
15.2°
near-range ambiguity
θ_min (binding) 15.2°
θ_max (PRF) 43.8°
0°30°60°
✓ Valid look angle
Mode Performance
Azimuth resolution3–10 m
Swath width50–400 km
Coverage rate★★★★
PRF constraintModerate
STRIPMAP — CROSS-TRACK VIEW MAPPING
STRIPMAP — TOP-DOWN VIEW PLAN
STRIPMAP — ALONG-TRACK VIEW AZIMUTH
STRIPMAP — 3D VIEW 3D
SWATH WIDTH
DOPPLER BW
AMBIGUITY (AASR)
🛰️ Platform Selector
✈️
Airborne
🛰️
Spaceborne
Airborne Params
Altitude8 km
Speed200 m/s
Spaceborne Params
Orbital Altitude514 km
Shared Params
Antenna Length (D)4 m
Chirp Bandwidth150 MHz
Frequency BandC (5.4 GHz)
Real System Presets
ORBIT / FLIGHT PATH VISUALISATIONAIRBORNE
PARAMETER COMPARISON
Parameter✈ Airborne🛰 Spaceborne
Airborne Advantages
Spaceborne Advantages
⚙️ Image Formation

SAR image formation is a 2D matched filtering operation: range compression (fast-time) followed by azimuth compression (slow-time).

Processing Chain
📦Raw Echo Data (I/Q)
↓
🔀Range Cell Migration (RCMC)
↓
📊Range Compression
↓
🔭Azimuth Compression
↓
🗺️SAR Image (SLC / GRD)
Algorithm
RAW DATA (I/Q)
RANGE COMPRESSED
2D SPECTRUM
FOCUSED SAR IMAGE (SLC)
IMPULSE RESPONSE FUNCTIONPSLR / ISLR
-13.3
dB
PSLR (sinc)
-9.8
dB
ISLR
46
dB
Processing Gain
🖥️ SAR Calculator
Params
Link Budget
Presets
Platform
Altitude (H)514 km
Velocity7600 m/s
Look Angle23°
Antenna
Length (D_az)4.8 m
Height (D_el)0.7 m
Waveform
Center Freq.9.65 GHz
Chirp BW300 MHz
PRF3000 Hz
Pulse Duration25 µs
System
Tx Power2260 W
System Loss3.5 dB
Noise Figure4 dB
Target σ⁰-10 dB
2.4
metres
Az. Res.
0.5
metres
Range Res.
55
km
Swath Width
14.2
dB
SNR
GEOMETRY CROSS-SECTION
RESOLUTION vs BANDWIDTH
SIMULATED SAR SCENE
FULL SYSTEM REPORT