Radar Antenna Array Aperture Extension via Time Division
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Solution Overview
Problem
Radar apparatuses using digital beam forming (DBF) face limitations in angular resolution due to limited antenna size and increased calculation amounts when trying to enhance aperture diameter and apply fast Fourier transform (FFT) processing.
Innovation Solution
A radar apparatus with two transmitting antennas positioned at opposed ends of regularly spaced receiving antennas, utilizing a signal processor for time and space FFT processing, and optionally including dummy antennas to unify amplitude and phase characteristics, allowing for equivalent aperture diameter enhancement and reduced calculation amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the antenna aperture diameter is increased to improve angular resolution, then measurement precision is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent creates a virtual copy of the transmitting antenna at a different time instance. By transmitting from two different antennas at opposite ends of the receiving antenna array in time-division manner, the system synthesizes an equivalent aperture that is approximately twice as large as the physical aperture, thereby improving angular resolution without adding physical antenna elements
Solution Approach 2:
The patent transitions from spatial dimension to time dimension by using time-division transmission. Instead of physically placing transmitting antennas at all positions simultaneously, the system transmits sequentially from different antennas at different time instances, effectively utilizing the time dimension to achieve virtual aperture extension
2Measurement precision
If digital beam forming is implemented with multiple transmitting antennas to enhance aperture, then measurement precision is improved, but calculation amount increases
Solution Approach 1:
The patent employs periodic time-division transmission where two transmitting antennas alternate in a regular pattern. This periodic action allows the signal processor to handle data from different time instances separately, applying DBF processing to each period's data and then combining results, thereby managing calculation complexity through structured periodic processing
3Measurement precision
If transmitting antennas are positioned at opposed ends of receiving antennas to double aperture, then measurement precision is improved, but antenna spacing requirements increase
Solution Approach 1:
The patent utilizes the time dimension to achieve aperture extension without proportionally increasing the spatial length. By transmitting from end antennas at different time instances rather than simultaneously, the system effectively doubles the aperture while maintaining a compact physical array configuration
4Productivity
If fast Fourier transform is applied in both time and space directions, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent segments the signal processing into two distinct stages: time-direction FFT processing for each receiving antenna's temporal signal, followed by space-direction FFT processing across the array of receiving antennas. This segmentation allows the system to apply FFT efficiently in both dimensions while maintaining manageable computational complexity through structured multi-stage processing
Data Source
AI summary
A radar apparatus includes: a plurality of receiving antennas disposed at regular spacings; two transmitting antennas which are positioned each at opposed ends of the receiving antennas, and a spacing of which away from the receiving antennas adjacent thereto is a natural number multiple of half a disposition spacing of the plurality of the receiving antennas; and a signal processor which, after the two transmitting antennas transmit electric waves in time divisions, and then one for each of the plurality of receiving antennas receives waves reflected from a target, subjects the obtained received signals to a digital beam forming process, in which case the signal processor, after subjecting the received signals to a fast Fourier transform process in a time direction, carries out a fast Fourier transform process in a space direction.