Angle Diversity MIMO Radar Single Pulse Beamforming
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Solution Overview
Problem
Conventional MIMO radar systems experience signal-to-noise ratio (SNR) loss due to the creation of broad subarray transmit beams, which limits angle estimation accuracy and increases with the number of transmit subarrays, while existing solutions require multiple dwells for sequential lobing, compromising measurement rate or Doppler resolution.
Innovation Solution
A radar system and method that transmit two or more narrow, skewed transmit beams from a single pulse using the same aperture, made distinguishable through techniques like TDMA, CDMA, or DDMA, allowing for superior angle estimation accuracy with only one dwell by forming two-way beams that overlap and are steered to achieve optimal beamwidth and SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If broad subarray transmit beams are used in conventional MIMO radar, then the effective aperture is increased, but signal-to-noise ratio (SNR) loss increases in proportion to the number of transmit subarrays
Solution Approach 1:
The transmit array is divided into multiple subarrays, each transmitting a distinguishable waveform. This segmentation enables the formation of multiple simultaneous beams while maintaining a large effective aperture through coherent combination of 2-way signals, resolving the contradiction between aperture size and SNR loss.
Solution Approach 2:
The patent combines 2-way signals from multiple subarrays coherently on receive, creating an equivalent 1-way aperture that is larger than the physical array. This merging approach maintains high SNR while achieving the benefits of a large aperture for improved angle estimation.
2Measurement precision
If conventional sequential lobing is used for angle estimation, then angle estimation accuracy is improved, but the measurement rate decreases due to requiring multiple successive dwells
Solution Approach 1:
The patent uses periodic waveform sequences (such as orthogonal codes or frequency codes) transmitted from different subarrays to create multiple skewed beams within a single dwell period. This periodic action enables sequential lobing-like angle estimation without requiring multiple successive dwells, thus maintaining high measurement rate.
Solution Approach 2:
Multiple skewed beams are formed simultaneously within one continuous dwell using distinguishable waveforms from different subarrays. This continuity allows angle estimation through sequential lobing principles without interrupting the measurement process, preserving both accuracy and measurement rate.
3Measurement precision
If the dwell time is increased to improve angle estimation accuracy, then measurement precision improves, but Doppler resolution is compromised
Solution Approach 1:
The radar dwell is segmented into multiple parallel beam processing channels, each handling a different skewed beam direction. This segmentation allows simultaneous angle estimation across multiple directions within the same dwell time, achieving high angle accuracy without extending the dwell duration that would degrade Doppler resolution.
Data Source
AI summary
A radar system includes an antenna array including a plurality of antenna elements; and a transmitter portion coupled to the antenna array, the transmitter portion being configured to sequentially transmit a first transmit beam and a second transmit beam from a single pulse, the first transmit beam and second transmit beam being formed using the same aperture of the antenna array, wherein a skew angle of the first transmit beam is distinct from a skew angle of the second beam. Such radar system alternatively transmitting through subarrays and receiving each via the entire array and combining the signals such that the transmit and receive parts of one of two 2-way beams point in the same direction and the transmit and receive parts of the second 2-way beam point in the same direction and these directions are within a standard beamwidth of each other.