Planar Monopulse Antenna Array Feed Network Design
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Solution Overview
Problem
Conventional monopulse radar systems face challenges in optimizing the sum pattern-to-sidelobe level (SLL) ratio while maintaining high directivity of the sum beam, particularly in achieving low SLLs for both sum and difference beams across a radiating aperture, especially in complex systems like military applications.
Innovation Solution
A planar monopulse radar apparatus with a distribution matrix that includes 0°/180° comparator components and crossover components, forming a passive, planar network to deliver both sum and difference beam distributions across the antenna array, utilizing Taylor and Bayliss weights to achieve low SLLs in both patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dish reflector/comparator combinations are used to implement monopulse radar functionality, then the system can achieve monopulse tracking, but the device complexity increases and the system becomes less suitable for planar array integration
Solution Approach 1:
The patent replaces the mechanical dish reflector/comparator system with an electromagnetic field-based planar array feed network. The distribution matrix uses electromagnetic signal routing through comparator components and crossover components to achieve monopulse functionality without mechanical structures, reducing device complexity while maintaining tracking capability
Solution Approach 2:
The distribution matrix serves multiple functions simultaneously: it generates sum patterns, difference patterns, and provides beam steering capabilities through a single integrated planar network. This multi-functionality eliminates the need for separate dish antennas and comparators, reducing overall system complexity
2Measurement precision
If Taylor weights are used for sum beam formation in planar patch arrays, then the directivity is maintained, but the sidelobe level cannot be optimized for both sum and difference beams simultaneously
Solution Approach 1:
The patent applies different weighting schemes to different parts of the signal distribution: Taylor weights are applied to the sum beam channels to maintain directivity, while Bayliss weights are applied to the difference beam channels to optimize sidelobe levels. The distribution matrix enables local application of different weightings to different beam channels
Solution Approach 2:
The feed network is segmented into separate sum and difference beam channels, each with independent weight application. The distribution matrix separates the signal paths to allow independent optimization of sum and difference beam patterns using different weighting schemes
3Measurement precision
If active amplification with phase shifters is used to obtain desired magnitudes and phases, then the beam forming accuracy is improved, but the device complexity and cost increase significantly
Solution Approach 1:
The patent uses passive, inexpensive comparator components and crossover components instead of expensive active amplifiers and phase shifters. These passive components achieve the required signal manipulation through electromagnetic field interactions rather than active electronic control, significantly reducing device complexity and cost
Solution Approach 2:
The distribution matrix uses passive components that automatically perform signal distribution and phase manipulation without requiring active control elements. The network self-configures the signal paths through its passive electromagnetic structure, eliminating the need for powered amplifiers and electronically controlled phase shifters
4Device complexity
If the aperture tails of Bayliss and Taylor distributions are shaped to be the same, then the feed network complexity is reduced, but less than half of the array's feeding is addressed
Solution Approach 1:
The distribution matrix applies different aperture tail shaping treatments to different regions of the array feeding. The network structure enables different weighting applications to different spatial regions, ensuring complete array coverage while maintaining simplified feed network design
Solution Approach 2:
The feed network is segmented to provide complete coverage of the array elements. The distribution matrix structure ensures that all array elements receive appropriate signaling, addressing the limitation of previous approaches that only covered less than half of the array feeding
Data Source
AI summary
A planar monopulse radar apparatus includes a planar distribution matrix coupled to a planar antenna array having a linear configuration of antenna elements. The planar distribution matrix is responsive to first and second pluralities of weights applied thereto for providing both sum and difference beam distributions across the antenna array.