AESA Subarray Synthetic Nulling for Reliable Ground Clutter Suppression
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Solution Overview
Problem
Radar systems face challenges in forming reliable and deep nulls due to phase and gain imperfections in active electronically scanned array (AESA) antennas, which are further exacerbated by environmental factors and pointing angles, leading to high sidelobe levels and noise interference.
Innovation Solution
The system employs multiple nulls by transmitting and receiving radar pulses with different patterns, averaging their returns to form a less noisy and potentially wider null window, utilizing subarrays to generate pulses with distinct null locations, and combining these signals to enhance signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple null patterns are used and averaged together, then the signal-to-noise ratio is improved and detection capability is enhanced, but the device complexity and processing requirements increase
Solution Approach 1:
The AESA antenna is divided into multiple subarrays, with each subarray generating a null pattern at a different location. This segmentation allows the system to create multiple specialized null patterns that can be averaged together, improving the overall signal-to-noise ratio while distributing the processing load across manageable subarray units.
Solution Approach 2:
The system transmits multiple radar pulses with different null patterns in sequence and averages their returns. This periodic transmission of varied null patterns allows the system to accumulate noise-reduced data over time, improving detection capability through temporal averaging while maintaining a structured approach to handling the increased data volume.
2Object-affected harmful factors
If deep nulls are formed to suppress ground clutter, then noise and interference are reduced, but the null formation becomes unreliable due to phase and gain imperfections
Solution Approach 1:
Multiple null patterns from different subarrays are combined through averaging to form a composite null window. This merging approach compensates for the imperfections of individual null patterns, as the statistical averaging process reduces the impact of phase and gain variations, resulting in a more reliable and consistent ground clutter suppression effect.
Solution Approach 2:
The system varies the null pattern parameters (location and shape) across multiple pulses by using different subarrays. This parameter variation allows the system to adapt to different environmental conditions and pointing angles, maintaining reliable null formation despite changes in temperature, element degradation, or target geometry.
3Area of stationary object
If wider null windows are created to cover more of the target window, then more noise is excluded, but the null depth may be reduced and sidelobe levels increase
Solution Approach 1:
The antenna aperture is segmented into multiple subarrays, each responsible for creating a null pattern in a specific region. By distributing the null-forming function across subarrays and averaging their outputs, the system achieves a wider effective null window while maintaining control over sidelobe levels through coordinated subarray operation.
Solution Approach 2:
Each subarray creates a null pattern that extends beyond the immediate target region, providing overlapping coverage. This excessive action in terms of individual null width, when combined through averaging, results in a broader effective null window with controlled sidelobe levels, as the overlapping patterns reinforce the null effect across a wider area without proportionally increasing sidelobes.
Data Source
AI summary
A radar system uses multiple nulls to improve detection capabilities. Multiple radar pulses are transmitted and or received, each with a different null pattern. The returns from each pulse are averaged together to form a null window that is less noisy and potentially wider than a single null pattern. This approach can improve the signal-to-noise ratio and make it easier to detect objects of interest. The system may generate individual pulses from an AESA divided into several subarrays. Each subarray produces a pulse with a null in a different location in the radiation pattern centered about a location of interest. The contemporaneous return signals are averaged together.