Radar Reflector Shape Optimization for Side Lobe Control
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Solution Overview
Problem
Existing radar systems face challenges in achieving a predetermined far field radiation pattern across a wide frequency band, particularly in millimeter-wave ranges, due to limitations in side lobe control and beam shaping for sectorial area surveillance.
Innovation Solution
A method involving geometrical optics calculations to determine the shape of a reflective surface, followed by physical optics analysis to adjust the radiation current and phase differences, resulting in a machined reflective surface that matches the desired radiation pattern, thereby constraining side lobes and optimizing beam characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional directive antennas are used, then the main beam can be directed in the required direction, but side lobes appear in unwanted directions causing interference
Solution Approach 1:
The reflector surface is divided into multiple zones with different geometrical characteristics. Each zone is optimized to control the radiation pattern locally, suppressing side lobes in specific directions while maintaining the main beam directionality. This local optimization approach allows precise control over the radiation pattern without compromising overall beam direction.
2Manufacturing precision
If the radiation pattern is optimized for a specific frequency, then beam characteristics are improved, but the antenna cannot maintain performance across a wide frequency band
Solution Approach 1:
The reflector geometry is pre-calculated using geometrical optics methods to achieve a predetermined far-field radiation pattern. The surface is then adjusted using a iterative optimization process that determines the required surface variations before manufacturing. This preliminary design phase ensures the reflector is optimized for wideband performance from the outset, maintaining radiation pattern precision across the entire frequency band.
3Manufacturing precision
If the reflective surface is made with high precision machining, then the radiation pattern accuracy is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The complex multi-zone surface optimization process is replaced by a unified geometrical optics calculation method. The reflector surface is defined by a continuous mathematical function rather than discrete zones, simplifying the manufacturing process. This substitution reduces manufacturing complexity while maintaining the precision needed for accurate radiation pattern control across wide frequency bands.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables radar antennas to maintain a low side lobe level and wide frequency band capability, effectively steering and shaping inspection beams within a circular sector area with improved beam control and reduced side lobe interference.
Implementation Method 1
The radar signal may be reflected towards a zone of surveillance by the reflective surface 16
Implementation Method 2
calculating a shape of a reflective surface based on geometrical optics with reference to the predetermined far field radiation pattern
Implementation Method 3
determining initial radiation current on the reflective surface for the calculated shape based on physical optics (PO)
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A method to manufacture a reflector for a radar antenna (10) is disclosed. The method comprises the steps of calculating a shape of a reflective surface (16) based geometrical optics; determining initial radiation current on the reflective surface based on physical optics; calculating the radiation pattern (24) of the calculated shape of the reflective surface from the initial radiation current; comparing the radiation pattern with a predetermined far field radiation pattern (18) to obtain a constrained radiation pattern (26); calculating a constrained radiation current on the reflective surface corresponding to the constrained radiation pattern; determining a phase difference between the initial radiation current and the constrained radiation current for each point of the reflective surface; varying the level of each point of the reflective surface to compensate the phase difference so as to obtain a matrix (30) defining an adjusted shape of the reflective surface; and applying the matrix to machine the reflective surface.