Sparse Receive Array with Steerable Transmit Beam for Low-Aliasing Radar
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Solution Overview
Problem
Traditional phased-array radar systems are unsuitable for applications like autonomous vehicles and drones due to their size, power requirements, cost, and limited beam-steering capabilities, which restrict their field of view and resolution, leading to a trade-off between field of view and Rayleigh resolution.
Innovation Solution
An antenna subsystem with a sparse receive antenna and an electronically steerable transmit antenna, where the receive antenna elements are spaced more than half a wavelength apart and the transmit antenna elements are spaced less than half a wavelength apart, allowing for spatial filtering to reduce aliasing and achieve high Rayleigh resolution with a narrow beam width without the need for a large number of antenna channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional phased-array radar system uses dense antenna elements spaced less than half a wavelength apart, then it achieves good beam steering capability and coverage, but the system becomes too large, heavy, expensive, and power-hungry for applications like autonomous vehicles and drones
Solution Approach 1:
The patent divides the antenna system into two separate functional segments: a sparse receive antenna array and an electronically steerable transmit antenna. The receive array uses widely spaced elements (more than half wavelength apart) to reduce weight and complexity, while the transmit antenna handles beam steering electronically. This segmentation allows each part to be optimized independently, resolving the contradiction between dense element requirements for steering and sparse element benefits for weight reduction.
2Device complexity
If the receive antenna elements are spaced more than half a wavelength apart to reduce the number of channels and system complexity, then spatial aliasing occurs producing side-lobes and grating lobes that hinder detection, but keeping elements closer together increases system complexity and cost
Solution Approach 1:
The patent introduces an electronically steerable transmit antenna as an intermediary component that works in conjunction with the sparse receive array. The transmit antenna's beam pattern acts as a spatial filter that suppresses the aliasing artifacts (side-lobes and grating lobes) generated by the widely spaced receive elements. This intermediary transmit beam enables the system to use sparse receive elements without suffering from spatial aliasing, thus reducing complexity while maintaining detection performance.
3Area of stationary object
If the radar system uses a fixed transmit beam that is wide (more than 20 degrees in azimuth) to cover a usable field of view, then the field of view coverage is adequate, but the Rayleigh resolution is limited and cannot achieve high angular precision
Solution Approach 1:
The patent makes the transmit beam dynamic through electronic steering capability. Instead of a fixed wide beam, the transmit antenna can electronically steer narrow beams to different positions within the field of view. This dynamic beam steering allows the system to maintain a narrow beam width (providing high Rayleigh resolution of approximately 2 degrees) while still covering the entire field of view by sequentially positioning the narrow beam at different locations, thus resolving the contradiction between wide coverage and high resolution.
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
This configuration enables a radar system to achieve a high Rayleigh resolution and significantly reduced aliasing, allowing for a narrow beam width of approximately 2° in both azimuth and elevation dimensions with fewer antenna channels, improving angular performance compared to prior systems.
Implementation Method 1
an array of transmit elements each configured to radiate a respective signal having the wavelength and each spaced apart from each adjacent one of the transmit elements by a respective second distance that is less than one half of the wavelength
Implementation Method 2
an array of receive elements each configured to receive a respective signal having a wavelength and each spaced apart from each adjacent one of the receive elements by a respective first distance that is more than one half of the wavelength
Data Source
AI summary
In an embodiment, an antenna subsystem includes a sparse receive antenna and an electronically steerable transmit antenna. The sparse receive antenna includes an array of electronically steerable receive elements each configured to receive a respective signal having a wavelength and each spaced apart from each adjacent one of the receive elements by a respective first distance that is more than one half of the wavelength. And the electronically steerable transmit antenna includes an array of transmit elements each configured to radiate a respective signal having the wavelength and each spaced apart from each adjacent one of the transmit elements by a respective second distance that is less than one half of the wavelength. To reduce aliasing, such an antenna subsystem can be operated to filter, spatially, a receive beam pattern generated by the receive antenna with a transmit beam pattern generated by the transmit antenna.