Extended Subaperture Imaging Method for Airborne Low Frequency Ultrawideband SAR Data

Area of Science:

• Radar Systems Engineering
• Signal Processing
• Remote Sensing

Background:

• Subaperture processing is crucial for real-time low-frequency ultrawideband synthetic aperture radar (LF UWB SAR) imaging due to improved algorithm parallelization.
• Longer synthetic apertures in LF UWB SAR lead to azimuth ambiguities, degrading image quality in traditional subaperture imaging.

Purpose of the Study:

• To theoretically analyze the cause and impact of azimuth ambiguities in LF UWB SAR subaperture imaging.
• To propose and validate an extended subaperture imaging method to overcome these ambiguities and enhance image quality.

Main Methods:

• Theoretical analysis of azimuth ambiguities in LF UWB SAR subaperture imaging.
• Development of an extended subaperture imaging technique involving subaperture length extension before Range Cell Migration Correction (RCMC).
• Removal of the extended subaperture data before Azimuth Compression (AC).

Main Results:

• The theoretical analysis identified the root cause of azimuth ambiguities in LF UWB SAR subaperture imaging.
• The proposed extended subaperture method effectively eliminates azimuth ambiguities by increasing subaperture length prior to RCMC.
• High-focused quality LF UWB SAR images were achieved, validated by simulated and real data.

Conclusions:

• The extended subaperture imaging method successfully addresses the azimuth ambiguity problem in LF UWB SAR.
• The technique significantly improves the focused quality of LF UWB SAR images, making it suitable for real-time applications.
• Validation with both simulated and real data confirms the method's effectiveness and theoretical correctness.