Passive Radar Antenna Array for Low-Altitude Target Detection
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Solution Overview
Problem
Existing passive radar systems face challenges in efficiently detecting low-profile low-altitude targets due to the need for multiple antennas and complex beamforming, which increases size, complexity, and vulnerability to jamming, while also requiring significant processing time.
Innovation Solution
A passive radar system utilizing a staring array of directional antennas coupled with separate processing stages, employing monopulse processing and overlap antenna patterns to achieve simultaneous, continuous illumination and detection of multiple targets, reducing size and vulnerability through directional accuracy and clutter suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple antennas are used for passive radar detection, then detection capability is improved, but system size and complexity increase
Solution Approach 1:
The system divides the antenna array into multiple sub-arrays, each responsible for detecting signals from specific spatial sectors. This segmentation allows the system to maintain detection capability across multiple directions while reducing the complexity of signal processing for each individual sub-array, as each handles only a portion of the total detection task.
Solution Approach 2:
The patent introduces a spatial dimension by arranging antennas in a three-dimensional configuration rather than a simple linear or planar array. This spatial arrangement enables the system to achieve omnidirectional or wide-area coverage using a compact number of antennas, effectively converting a one-dimensional complexity problem into a three-dimensional solution space.
2Measurement precision
If beamforming processing is applied, then detection accuracy is improved, but processing time increases
Solution Approach 1:
The system performs preliminary spatial filtering and signal separation by assigning specific antennas to specific spatial sectors before the main detection process. This pre-organization of antenna-subarray mappings allows the beamforming process to proceed more efficiently, as the spatial structure is already established and does not need to be computed in real-time during signal processing.
Solution Approach 2:
The patent replaces complex mechanical beamforming adjustments with a fixed geometric arrangement of antennas in space. By using the physical spatial positions of antennas rather than dynamic electronic beam steering, the system achieves beamforming accuracy without the computational overhead and time delays associated with real-time electronic phase and amplitude adjustments.
3Object-affected harmful factors
If passive radar system is made undetectable by lacking EM transmission, then stealth capability is improved, but detection range is limited
Solution Approach 1:
The system uses reflected electromagnetic waves from environmental objects (such as buildings, terrain, or other structures) as intermediaries to transmit information about targets. Instead of directly transmitting signals to illuminate targets, the passive radar system captures signals that have already interacted with the environment, using these reflected signals as a medium to indirectly detect targets while maintaining stealth.
Solution Approach 2:
The patent employs signal copying by capturing copies of transmitted electromagnetic waves that have reflected off environmental objects and then off targets. By analyzing these copied signals rather than using direct transmission, the system achieves target detection without emitting its own electromagnetic signals, thus maintaining stealth while extending detection range through the use of existing electromagnetic energy in the environment.
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 provides high directional accuracy, reduced size and weight, enabling fast and simultaneous detection of multiple low-profile low-altitude targets with enhanced detection range and resistance to interference.
Implementation Method 1
The passive radar system receives these signals in two ways: first is the signal directly from a transmitter (direct or reference signal), second is the signal reflected from an object of interest (reflected or scattered from target signal)
Data Source
AI summary
A passive radar system and method of detection of low-profile low altitude targets based on the application of Low Earth Orbit (LEO) and Very Low Earth Orbit (VLEO) satellite signals. The staring array of directional antennas covers the entire sky and provides continuous illumination (receiving reflected satellite signals) from multiple targets for fast detection, recognition, and target tracking and increasing detection range. The coupling of each directional antenna with a separate receiver channel allows the fast continuous process of information from all targets simultaneously. Monopulse processing of signals from reference sub-set of antennas with overlap antenna patterns provides the highest directing accuracy and better clutter/noise and media influence suppression. A directional antenna array does not need a beam-forming module. The system has a small weight, and size may be portable or mounted on a light vehicle or small drone because small size and weight.