MIMO Radar Antenna Layout for High Angle Resolution on Compact PCBs
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Solution Overview
Problem
Existing MIMO radar sensors for motor vehicles require large, expensive high-frequency capable circuit boards to achieve high angle resolution in both azimuth and elevation, leading to increased costs and limited design flexibility.
Innovation Solution
The antenna arrays are disposed along the edges of a rectangular circuit board with high-frequency modules placed in the central region, allowing for optimal space utilization and flexible antenna configuration to achieve large apertures in both directions without the need for extensive board size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the antenna assemblage is made large to achieve high angle resolution in both azimuth and elevation, then the angle resolution is improved, but the circuit board size and cost increase
Solution Approach 1:
The patent transitions from a conventional planar antenna arrangement to a three-dimensional configuration by stacking transmitting and receiving antenna arrays at different heights (z-direction) while maintaining edge-based positioning. This vertical dimensionality allows the system to achieve large effective aperture for high angle resolution without proportionally increasing the circuit board footprint, as the antennas utilize the z-space above the board surface.
Solution Approach 2:
The antenna assemblage is segmented into four distinct edge-based arrays: transmitting antennas along two opposite edges and receiving antennas along the other two opposite edges. This segmentation allows each edge array to be optimized independently for its specific function (transmission or reception) while collectively achieving the desired large aperture and high angle resolution performance.
2Measurement precision
If larger spacings between antennas are used to improve angular accuracy, then angle separation capability is improved, but ambiguities in angle estimation increase
Solution Approach 1:
By introducing the vertical z-dimension with transmitting and receiving antennas at different heights, the system creates a three-dimensional spatial sampling pattern. This additional dimensional information helps disambiguate angle estimates that would be ambiguous in a purely two-dimensional planar arrangement, as the same azimuth angle produces different spatial phase relationships when observed from multiple vertical levels.
Solution Approach 2:
The patent employs asymmetric positioning where transmitting antennas are located along two opposite edges while receiving antennas are located along the other two opposite edges, creating an asymmetric transmit-receive geometry. This asymmetric configuration, combined with the vertical offset between transmit and receive arrays, generates unique spatial signature patterns that reduce angle estimation ambiguities compared to symmetric arrangements.
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 high angle resolution in both azimuth and elevation while minimizing material costs, providing design freedom for optimizing angular resolution and reducing ambiguities, thus enhancing the performance of the radar sensor.
Implementation Method 1
Radar sensors are used for surroundings monitoring in driver assistance systems or in autonomous vehicle guidance systems for motor vehicles
Implementation Method 2
The received signal is mixed with a portion of the signal transmitted at the reception time, thereby yielding an intermediate-frequency signal whose frequency corresponds to the frequency difference between the transmitted signal and the received signal. That frequency difference depends on the signal transit time (because of the frequency modulation) and also on the relative speed of the object (because of the Doppler effect)
Implementation Method 3
transmitting antennas within each array being offset from one another in a z direction while the two arrays of the transmitting antennas are offset from one another in a y direction
Data Source
AI summary
A MIMO radar sensor for motor vehicles, having an antenna assemblage on a rectangular circuit board whose edges define a y direction and a z direction. The antenna assemblage includes at least two arrays of transmitting antennas and at least two arrays of receiving antennas. Transmitting antennas within each array are offset from one another in a z direction, and the two arrays of the transmitting antennas are offset from one another in a y direction. The receiving antennas within each array are offset from one another in a y direction, and the two arrays of the receiving antennas are offset from one another in a z direction. A high-frequency module is disposed in a central region of the circuit board between the arrays of the transmitting and receiving antennas.