Sparse Phased Array Radar for High-Resolution Moving Target Imaging
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Solution Overview
Problem
Current radar imaging systems for security screening face challenges in achieving high refresh rates, fine resolution, and multiple depths of focus, especially when imaging moving subjects, and are limited by mechanical scanning and susceptibility to natural radiation sources.
Innovation Solution
A radar imaging system with a plurality of transmitter and receiver elements, coupled with a processor that transmits coded signals, decodes return signals, and aligns and sums them to produce images, using techniques like code division multiplexing and coherent MIMO processing to achieve high refresh rates and fine resolution at various distances, including through visual impairments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanically scanned reflector antenna is used to detect electromagnetic radiation, then the system can image natural radiation from the body, but the system cannot achieve fine image resolution at distant ranges and cannot capture images of walking persons due to slow refresh rate
Solution Approach 1:
The patent replaces the mechanical scanning system with an electronic phased array radar system. Instead of physically moving a reflector antenna to scan and capture images, the invention uses electronically controllable antenna elements that can rapidly steer beams and capture multiple lines of sight simultaneously, achieving both fine resolution and high refresh rates necessary for imaging moving subjects.
Solution Approach 2:
The patent divides the imaging function into multiple antenna elements arranged in a phased array configuration. Each element captures a specific line of sight, and by combining signals from multiple elements through signal processing, the system achieves fine cross-range resolution while maintaining high refresh rates through parallel data acquisition.
2Productivity
If conventional phased array radar technology is used, then the system can provide images with multiple depths of focus and fast refresh times, but the cost becomes excessive due to requiring the whole aperture to be filled with transmitter and receiver mm wave elements
Solution Approach 1:
The patent implements a sparse phased array configuration where only selected antenna elements are populated with transmitters and receivers, rather than filling the entire aperture. This segmentation approach maintains the parallel data acquisition capability for fast refresh rates while significantly reducing the number of expensive mm-wave components required.
Solution Approach 2:
The patent uses signal processing techniques to synthesize additional virtual antenna elements from the physical sparse array. By creating virtual elements through coherent signal combining and processing, the system achieves the imaging performance of a fully populated array while using far fewer physical components, thereby reducing cost.
3Object-affected harmful factors
If radiometer systems are used to image natural electromagnetic radiation, then the system can penetrate through clothing, but the system is susceptible to variable natural radiation sources that affect image contrast and requires the person being screened to remain stationary
Solution Approach 1:
The patent employs periodic transmission of coded radar signals at controlled time intervals, allowing the system to actively illuminate the target and measure reflected signals. This periodic active illumination provides consistent, controllable signal returns that are not affected by variable natural radiation sources, ensuring reliable image contrast while maintaining the ability to penetrate clothing.
Solution Approach 2:
The patent uses coded modulation schemes where transmission signals are pre-encoded with known patterns. By correlating the received signals with these predetermined codes, the system can distinguish target reflections from background radiation and noise, improving image contrast and reliability without requiring the subject to remain stationary.
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 enables high-resolution, real-time imaging of moving subjects with multiple depths of focus, reducing the impact of natural radiation variability and improving image quality compared to traditional systems.
Implementation Method 1
a radar array for use in an imaging system, said radar array comprising: a plurality of transmitter elements; a plurality of receiver elements for receiving a plurality of coded return signals from one or more objects within an area of interest
Implementation Method 2
transmitting a plurality of coded pulses from a plurality of transmitter elements toward the area of interest
Implementation Method 3
receiving a plurality of coded return signals reflected from the area of interest
Data Source
AI summary
A radar imaging system for capturing an image of an object within an area of interest through at least one visual impairment. The radar imaging system comprises at least one radar array. The radar array includes a plurality of transmitter elements and a plurality of receiver elements for receiving a plurality of coded return signals from an object through the at least one visual impairment. The system further comprises at least one processor coupled to the transmitter and receiver elements, which is adapted to transmit a plurality of differently coded signals toward the object and the at least one visual impairment; decode the plurality of coded return signals received by each of the receiver elements; extract from the decoded return signals a multiplicity of captured signals for each transmitter to receiver path; focus the multiplicity of signals on all points of interest within the area of interest by aligning the multiplicity of captured signals to be co-incident from a particular point within the area of interest; and sum the aligned signals to produce an image of the object. A method for capturing an image of an object in an area of interest through at least one visual impairment is also provided.