MIMO Antenna Spacing for 3D Radar Grating Lobes
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Solution Overview
Problem
Conventional MIMO antenna arrangements for 3D radar imaging suffer from ambiguous angle representation, grating lobes, coupling between transmitting and receiving antennas, and difficulties in Doppler evaluation, especially in scenarios with moving targets or static objects from a moving platform.
Innovation Solution
A MIMO antenna arrangement with uniformly lined up transmitting and receiving antennas, strategically positioned to achieve a gapless, uniform virtual array with high decoupling, allowing for clear angular representation and effective Doppler processing, using orthogonal signals and additional passive antenna elements for improved antenna patterns and pre-focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MIMO antenna arrangements are used, then transverse resolution is improved through virtual aperture enlargement, but ambiguous angle representation and grating lobes occur
Solution Approach 1:
The patent applies local quality by differentiating the spacing of antenna elements based on their position within the array. Specifically, the spacing between adjacent transmitting antennas is set to λ/2, while the spacing between transmitting and receiving antennas is set to λ/4. This non-uniform local spacing strategy eliminates grating lobes in specific angular regions while maintaining the virtual aperture enlargement benefit, thereby resolving the contradiction between improved transverse resolution and accurate angle representation.
2Device complexity
If transmitting and receiving antennas are positioned close together, then device complexity is reduced, but coupling between antennas increases
Solution Approach 1:
The patent resolves the contradiction between compactness and coupling by precisely controlling the spatial parameters of antenna elements. By setting the spacing between transmitting antennas to λ/2 and between transmitting/receiving antennas to λ/4, the design achieves a compact arrangement while the specific parameter values prevent strong coupling effects. This parameter optimization allows close positioning without significant interference, maintaining both compactness and low coupling.
3Ease of manufacture
If uniform antenna spacing is used, then manufacturing is simplified, but grating lobes and ambiguous angle representation occur
Solution Approach 1:
The patent implements local quality by creating two distinct uniform spacing patterns: λ/2 spacing within transmitting antenna groups and λ/4 spacing between transmitting and receiving antenna groups. This localized differentiation in spacing quality eliminates grating lobes and improves angular measurement accuracy while maintaining manufacturing simplicity through the repetition of these standardized spacing patterns across the array.
4Measurement precision
If additional receiving antennas are added for Doppler evaluation, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing receiving antennas that serve multiple functions: they receive reflected signals for 3D imaging and simultaneously enable Doppler evaluation for moving target detection. The same physical receiving antenna elements are used for both imaging and Doppler measurements, eliminating the need for separate dedicated Doppler sensors. This multi-functional approach improves measurement capability while avoiding the device complexity increase that would result from adding separate antenna elements.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A MIMO antenna array for three-dimensional radar imaging comprises a first transmitting antenna group (110), a second transmitting antenna group (120), and a receiving antenna group (130). The first transmitting antenna group (110) comprises at least N transmitting antennas arranged uniformly along a first line (210) with a maximum transmitter spacing (d1). The second transmitting antenna group (120) comprises at least N transmitting antennas arranged uniformly along a second line (220) with the maximum transmitter spacing (d1). The receiving antenna group (130) comprises M receiving antennas arranged uniformly along at least a third line (230) with a maximum receiver spacing (d2). A minimum spacing (d3) is maintained between the receiving antennas and the transmitting antennas of the first transmitting antenna group (110) along the first line (210).Furthermore, the minimum distance (d3) along the second line (220) is also formed between the receiving antennas and the transmitting antennas of the second transmitting antenna group (120).