SAR Antenna Irregular Pulse Timing Azimuth Resolution
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Solution Overview
Problem
Conventional synthetic aperture radar systems face a trade-off between achieving high azimuth resolution and large swath width, requiring high pulse repetition frequency (PRF) for high resolution but low PRF for wide swaths, leading to heavy and expensive satellite-based SAR systems due to the need for multiple receive apertures.
Innovation Solution
A high-resolution synthetic aperture radar device with a smaller antenna area is achieved by emitting pulse signals at irregular time intervals, using fewer than three azimuth apertures, and employing resampling methods to reconstruct data gaps, while operating multiple transmitting antennas in frequency multiplex to maintain high signal-to-noise ratio and reduce peak power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high pulse repetition frequency (PRF) is used to achieve high azimuth resolution, then azimuth resolution is improved, but swath width is reduced
Solution Approach 1:
The receiving antenna is divided into multiple sub-apertures arranged in elevation, which are then combined to form fewer azimuth apertures (fewer than three). This segmentation allows the system to achieve high azimuth resolution with reduced PRF by distributing the aperture function across multiple elevation elements, resolving the contradiction between resolution and swath width.
Solution Approach 2:
The patent transitions from conventional azimuth-only aperture arrangement to a three-dimensional aperture distribution utilizing elevation, azimuth, and time dimensions. By arranging sub-apertures in elevation and using irregular pulse timing, the system creates a volumetric sampling pattern that achieves high resolution without requiring high PRF, thereby maintaining large swath width.
2Measurement precision
If multiple receive apertures are used to achieve high azimuth resolution and large swath width, then imaging capability is improved, but antenna size and system weight increase
Solution Approach 1:
Instead of using multiple complete receive apertures, the patent segments a single large antenna into multiple sub-apertures in elevation that form fewer azimuth apertures. This segmentation achieves the required imaging capability with a reduced number of functional apertures, directly reducing antenna size and weight while maintaining high resolution and large swath width.
Solution Approach 2:
Each sub-aperture in elevation serves multiple functions: it contributes to azimuth resolution, enables large swath coverage through elevation diversity, and participates in the irregular sampling pattern. This multi-functionality eliminates the need for separate dedicated apertures for each function, reducing overall system weight and complexity.
3Productivity
If regular pulse emission is used for scanning, then scanning rate is improved, but data gaps occur at the same points leading to black stripes in SAR images
Solution Approach 1:
The patent employs irregular pulse repetition intervals dynamically adjusted according to the specific imaging requirements and aperture configuration. This dynamic timing strategy ensures that pulses are emitted at optimally spaced intervals that prevent systematic data gaps while maintaining high scanning rates, eliminating the black stripe problem associated with regular pulsing.
Solution Approach 2:
The irregular pulse timing strategy incorporates feedback from the aperture configuration and imaging requirements to optimize pulse emission intervals. By adapting the pulse timing based on the specific sub-aperture arrangement and desired coverage, the system prevents data gaps from occurring at the same spatial locations, thereby eliminating black stripes while maintaining high productivity.
Data Source
AI summary
The invention relates to a high-resolution synthetic aperture radar device (10) comprising at least one transmitting antenna (TX1-TX3) for producing and emitting radar pulses for scanning an object (12), a receiving antenna (14) for receiving the radar beams (20, 22, 24) emitted and reflected by an object, wherein the receiving antenna (14) has several sub-apertures (RX1-RX17) arranged along elevation, which form a minimum of azimuth apertures, wherein the high-resolution synthetic aperture radar device is embodied such that pulse signals (18) are emitted at irregular time intervals.