Interferometric Radar Rotating Antenna Displacement Measurement
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Solution Overview
Problem
Conventional rotating-antenna interferometric synthetic-aperture radars are limited in measuring displacement vectors and providing three-component displacement maps and digital elevation maps, as they primarily detect radial components and suffer from secondary lobes, making them unsuitable for monitoring large structures like hillsides and buildings.
Innovation Solution
An interferometric radar system with a rotating antenna oriented orthogonal to the plane of rotation, utilizing a single or dual linear/circular-polarization antennas, capable of acquiring data over arcs and processing interferograms to obtain three-component displacement maps and digital elevation maps, while minimizing secondary lobes through windowing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rotating antenna SAR uses the entire circumference for synthesis, then azimuth and elevation information is provided, but marked secondary lobes appear making it unsuitable for measuring small displacements
Solution Approach 1:
The patent segments the circular rotation path into a linear approximation by using small angular steps (Δθ << 1 radian) and limiting the synthesis to a subset of the circumference rather than the entire circle. This segmentation approach transforms the closed-loop circular path into an effectively open linear path, eliminating secondary lobes while maintaining the ability to measure small displacements for monitoring applications.
2Area of stationary object
If a rotating antenna performs 360-degree rotation, then complete coverage is achieved, but the system is slow as it must stop and go back
Solution Approach 1:
The patent applies partial action by using only a portion of the full circular rotation (limiting the synthesis to a subset of the circumference) rather than requiring complete 360-degree coverage. This allows the antenna to rotate continuously in one direction without stopping and reversing, significantly increasing acquisition speed while still providing sufficient coverage for monitoring applications through multiple passes.
3Measurement precision
If conventional GB-SAR moves antenna along a linear axis, then displacement maps are obtained, but the system is slow compared to rotating antenna
Solution Approach 1:
The patent transitions from linear motion to circular/curved motion by rotating the antenna along a circular path. This curved trajectory allows continuous rotation without stopping and reversing, dramatically increasing acquisition speed while maintaining displacement measurement capability through interferometric processing of the curved aperture data.
4Device complexity
If rotating antenna SAR detects radial component only, then simple processing is achieved, but three-component displacement maps and DEM cannot be obtained
Solution Approach 1:
The patent adds dimensional information by utilizing the orthogonal orientation of the antenna's direction of sight relative to the plane of rotation. This geometric configuration, combined with interferometric processing of data acquired along the curved path, enables extraction of three-component displacement vectors and digital elevation maps from a single acquisition, transforming the system from radial-only detection to full 3D measurement capability.
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
Enables fast acquisition of three-component displacement maps and digital elevation maps, overcoming the limitations of conventional systems by measuring displacement vectors and providing accurate elevation information without secondary lobes, enhancing monitoring capabilities for large structures.
Implementation Method 1
interferometric radar with rotating antenna
Implementation Method 2
GB-SARs (Ground-Based Synthetic-Aperture Radars)
Data Source
Figure 1~2
Figure 3
AI summary
An interferometric radar comprising an arm (2), which rotates with respect to an axis (z) of a plane (zx) orthogonal to an axis of rotation (y), a system of linear- polarization antennas (1), which is fixed to said arm (2) for describing complete revolutions along a circular path (c) about said axis (y) and is oriented in a direction of sight (a) parallel to the axis (y), motor-drive means (3) for driving the arm (2), a data-acquisition and processing unit (10) operatively connected to said antenna (1) for acquiring a succession of images detected by the antenna during its revolution about the axis (y) and making differential interferometric calculations for measuring at least one component of the displacement of one ' or more targets in the field of view, or else for measuring the digital elevation map (DEM) of the scenario- in the field of view.