Adaptive Sidelobe Blanking for Ship Motion Compensation
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Solution Overview
Problem
Existing radar systems with sidelobe blanking (SLB) systems face challenges in maintaining effective interference mitigation due to lack of roll angle compensation, especially in moving platforms like ships, where mechanical approaches are impractical and electronic beam steering is limited by the small number of antenna elements.
Innovation Solution
The implementation of an electronic method for steering the auxiliary antenna's horizontal fan beam pattern, using a ship motion compensator component that adjusts phase and amplitude weighting coefficients based on platform motion data from IMU and GPS, to dynamically compensate for pitch, yaw, and roll angles, ensuring effective sidelobe blanking coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical rotation or servomechanism is used for motion compensation, then roll angle compensation can be achieved, but the mounting axle being inline with the radar beam makes the approach difficult to implement
Solution Approach 1:
The patent replaces the mechanical servomechanism system with an electronic beam steering system. Instead of physically rotating the auxiliary antenna using mechanical components, the invention uses electronic phase and amplitude weighting coefficients to steer the beam pattern, achieving roll angle compensation without mechanical complexity or mounting constraints.
Solution Approach 2:
The patent changes the electrical parameters (phase and amplitude weighting coefficients) of the auxiliary antenna elements to achieve beam steering. By dynamically adjusting these parameters based on platform motion data, the system achieves roll angle compensation through parameter modification rather than mechanical movement.
2Adaptability or versatility
If electronic beam steering is used for motion compensation, then the system can adapt to platform motion, but the small number of antenna elements in the auxiliary antenna limits the capability to rotate the antenna pattern
Solution Approach 1:
The patent makes the auxiliary antenna beam pattern dynamic by continuously adjusting the phase and amplitude weighting coefficients based on real-time platform motion data. This dynamic adaptation allows the limited-number-element auxiliary antenna to effectively track and compensate for platform roll motion, achieving adaptability without increasing element count.
Solution Approach 2:
The patent compensates for the limited spatial rotation capability of the auxiliary antenna by introducing temporal dimension - continuously updating the beam pattern through real-time coefficient adjustment. This transforms the static limitation of few elements into a dynamic solution where the beam pattern adapts over time to match platform motion.
3Reliability
If the auxiliary antenna is positioned to always steer near the horizon to blank land-based EM interferences, then sidelobe blanking effectiveness is improved, but motion compensation becomes necessary to maintain horizon alignment
Solution Approach 1:
The patent implements a feedback mechanism where platform motion data from IMU and GPS sensors is continuously fed into the beam steering generator. This feedback loop allows the auxiliary antenna beam pattern to automatically adjust and maintain horizon alignment despite platform motion, preserving sidelobe blanking effectiveness without requiring complex mechanical compensation systems.
Solution Approach 2:
The system uses the platform's own motion data to automatically compensate for its motion effects. The auxiliary antenna beam steering is self-adjusting based on real-time platform orientation information, eliminating the need for external or mechanical compensation systems while maintaining effective horizon-aligned sidelobe blanking.
Data Source
AI summary
A motion compensation method and system is included in a radar antenna system mounted on a moving platform which is subject to pitch, yaw and roll. The radar antenna system includes a main array antenna, and an auxiliary antenna. The auxiliary channel associated with the auxiliary antenna utilizes roll, pitch and yaw angle motion compensations as its auxiliary antenna always steers a horizontal fan shape beam at the horizon to blank any surface (land or sea) based EM interferences. Such motion compensations are provided by a ship motion compensator component and process included within the antenna system. The ship motion compensator component in response to platform motion signals indicative of changes in platform motion angles generates new sets of values using an initial set of weighting coefficient values as a function of such angle motion changes. This produces changes in both amplitude and phase weighting coefficient values which results in both the quadrant phase rotation and the element weighting rotation. The process steers and spreads out the received auxiliary antenna pattern making sidelobe coverage broad enough to compensate for such changes in platform motion.