Sparse Radar Aperture Layout for Immediate Orbit Determination
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Solution Overview
Problem
Current ground RF radar systems are limited in range and size detection, and ground-based optical systems are hindered by lighting conditions and weather, making them inadequate for 24/7 surveillance and threat mitigation in space, particularly in synchronous orbits like geosynchronous orbits, where traditional phased arrays provide poor cross-range resolution and require long-arc tracking.
Innovation Solution
A widely-spaced antenna radar system with aperiodic lattice and unequal element patterns, capable of high angular resolution, operating at high frequencies, and enabling immediate orbit determination without long-arc tracking, using angle of arrival for 3D positioning and cross-range velocity measurement, and mitigating grating lobes, allowing for detection and characterization of smaller objects in synchronous orbits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional phased array radar systems are used for space surveillance, then they can detect objects in space, but they provide poor cross-range resolution and require long-arc tracking
Solution Approach 1:
The patent transitions from traditional 2D planar arrays to 3D volumetric aperture configurations, utilizing elevation angle measurements in addition to azimuth. This dimensional expansion enables immediate 3D positioning and cross-range velocity measurement without requiring long tracking arcs, directly resolving the contradiction between measurement precision and time loss.
Solution Approach 2:
The patent divides the radar aperture into multiple widely-spaced sensor elements distributed in three-dimensional space. This segmentation creates a sparse aperture configuration where each element contributes to angular resolution in both azimuth and elevation, enabling high cross-range resolution without requiring a physically large continuous array or extended tracking time.
2Reliability
If ground-based optical monitoring systems are used, then they can provide surveillance, but they are limited by lighting conditions, cloud cover and local weather
Solution Approach 1:
The patent replaces optical monitoring systems with radio frequency radar systems. This substitution eliminates dependence on visible light and atmospheric transparency, allowing 24/7 surveillance regardless of lighting conditions, cloud cover, or weather. The RF waves penetrate atmospheric conditions that block optical signals, directly resolving the reliability versus weather interference contradiction.
3Measurement precision
If widely-spaced antenna arrays are used, then angular resolution improves, but grating lobes are generated
Solution Approach 1:
The patent employs non-uniform, aperiodic spacing patterns for the antenna elements rather than regular periodic grids. This asymmetric configuration disrupts the formation of grating lobes while maintaining the large baseline distances necessary for high angular resolution. The irregular spacing ensures that constructive interference occurs only in the desired directions, eliminating the harmful grating lobe effect.
Solution Approach 2:
The patent applies different spacing characteristics to different regions of the aperture configuration. By optimizing local element positions and spacing variations throughout the array, the system achieves high overall angular resolution while locally controlling grating lobe formation. Each region's spacing is tailored to contribute to resolution without generating harmful interference patterns.
4Length of stationary object
If traditional radar systems are used, then they can detect objects, but they are limited in range and size detection capability
Solution Approach 1:
The patent utilizes three-dimensional aperture synthesis with elevation component addition, enabling simultaneous measurement of range, cross-range position, and cross-range velocity. This dimensional enhancement provides sufficient geometric diversity to characterize object size and shape at extended ranges, resolving the contradiction between detection range and size characterization precision.
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 system achieves very high angular resolution, enabling detection of baseball-sized objects in geosynchronous orbits, immediate orbit determination, and effective threat mitigation, with comprehensive coverage and increased EIRP, allowing for precise imaging and characterization of objects in synchronous orbits without the need for external assets or satellites.
Implementation Method 1
System and method for space domain awareness using a sparse widely-spaced radar aperture
Implementation Method 2
receive a signal reflected from the space object
Implementation Method 3
using angle of arrival for 3D positioning and cross-range velocity measurement
Data Source
AI summary
The present technology describes a widely-spaced antenna radar array for Space Domain Awareness capable of object detection, characterization, imaging and, if unfriendly, threat mitigation. It features (1) very high angular resolution due to the very wide spacing of the sensors, enabling the detection of baseball size objects in GSO, (2) operation at high frequencies enabling characterization of smaller objects because of the ability to mitigate tropospheric effects, (3) operation at varied frequencies enabling threat mitigation and imaging, (4) immediate orbit determination in a single pass without the need for long-arc tracking due to the wide spacing and high precision angle of arrival (AOA) and (5) mitigation of grating lobes caused by the sparse antenna configuration, enabling the sensors to be placed at great distances.