Active Antenna Array Phase Difference Target Location
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Solution Overview
Problem
Existing radar systems face challenges in accurately determining the angular location of close targets due to impractical time-of-flight measurements and require large, expensive, and bulky antenna arrays with many elements to achieve high directional resolution.
Innovation Solution
An active antenna array with switchable elements that produce pairs of beam patterns with identical far-field radiation patterns but offset origins, allowing for phase difference analysis to determine the angular location of targets, enabling the same resolution with fewer elements and reducing system size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of antenna elements are used to achieve high directional resolution, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The antenna array is segmented into multiple sub-arrays, each capable of forming independent beam patterns. By dividing the full array into smaller functional units, the system achieves high angular resolution through coordinated operation of segments rather than requiring all elements to be simultaneously active for each measurement, thereby reducing the effective complexity for each resolution measurement.
Solution Approach 2:
The invention introduces a temporal dimension to the measurement process by sequentially activating different sub-arrays at different time periods. This transforms a spatial problem (requiring many simultaneous elements) into a temporal sequence of measurements, allowing high angular resolution to be achieved through time-multiplexed operation of fewer elements.
2Measurement precision
If a large number of antenna elements are used to achieve high directional resolution, then measurement precision is improved, but the physical size of the system increases
Solution Approach 1:
By segmenting the antenna array into multiple sub-arrays that can be independently activated, the system achieves high angular resolution without requiring all antenna elements to be physically present and active simultaneously. This allows the same resolution performance to be achieved with a more compact physical footprint.
Solution Approach 2:
The invention moves from a purely spatial arrangement where all elements must be present to achieve resolution to a spatio-temporal approach where different spatial subsets are activated at different times. This dimensional transformation allows high resolution with fewer physically present elements at any given moment, reducing the required array area.
3Measurement precision
If time-of-flight measurement is used to determine target distance, then range measurement is achieved, but it becomes impractical for close targets
Solution Approach 1:
The invention changes the measurement parameter from time-of-flight to phase difference measurement. By measuring the phase difference of signals received at different antenna elements or sub-arrays, the system can accurately determine target distance and angle even for very close targets where the time-of-flight is too short to be practically measured.
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 approach allows for accurate target location with fewer elements, enhancing performance and reducing the radar cycle time while maintaining high angular resolution, and can adapt to moving targets by measuring velocity and correcting phase errors.
Implementation Method 1
one known antenna configuration, shown in Figure 2, is called a phased array and employs an array of antenna elements Φ, each one connected to a source or detector 21 of radiation by a different phase offset
Implementation Method 2
Many of these include elements which comprises areas of a conductive waveguide (such as a rod) through which radiation can escape by evanescent coupling
Implementation Method 3
In such applications alternative modulation schemes which monitor the phase of signals can be used
Implementation Method 4
The use of radar to determine the distance to a target is well known
Data Source
Figure 1a~1b
Figure 2~3
Figure 4a~4b
AI summary
An active antenna array is arranged to activate subsets of switchable elements causing the antenna to form a first beam having a first beam pattern, and later to form a second beam having a second beam pattern of substantially identical far field radiation pattern to the first beam pattern but with different origins. A receiver receives radiation reflected from a target back to the antenna when the antenna is configured with the first beam pattern and then when configured with the second beam pattern, and compares the phase of the radiation received at the receiver when the antenna is configured with the first beam pattern with the phase of the radiation received at the receiver when the antenna is configured with the second beam pattern to provide a phase difference signal. A target locating means determines the angular location of the target from the phase difference signal.