Phased Array Acoustic Transducer 20-Degree Beam Angle
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Solution Overview
Problem
Existing underwater acoustic Doppler sonar systems with phased array transducers are limited to a beam angle of 30 degrees, which restricts profiling range, increases the likelihood of signal obstruction, and introduces spatial aliasing due to the inability to achieve a beam angle less than 30 degrees without degrading the beam pattern with grating lobes.
Innovation Solution
A phased array acoustic transducer with elements spaced at one-half wavelength and grouped in six distinct phases with a 60-degree phase difference, allowing for the generation of acoustic beams inclined at 20 degrees from the normal axis, reducing grating lobe artifacts and improving profiling range and signal clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the beam angle is reduced to less than 30 degrees, then profiling range is improved and signal obstruction is reduced, but grating lobes appear and spatial aliasing occurs
Solution Approach 1:
The patent changes the electrical phase difference parameter from the conventional 90 degrees (four phases) to 60 degrees (six phases). This parameter change allows the beam angle to be reduced to 20 degrees while maintaining beam pattern quality by preventing grating lobe formation. The modified phase parameter fundamentally alters the beamforming characteristics to resolve the contradiction between narrow beam angle and beam pattern integrity.
2Object-affected harmful factors
If the beam angle is reduced to less than 30 degrees, then signal obstruction is reduced, but grating lobes appear and spatial aliasing occurs
Solution Approach 1:
The patent modifies the electrical phase parameter from 90 degrees to 60 degrees, creating six distinct phases instead of four. This parameter change enables a 20-degree beam angle that simultaneously reduces signal obstruction from surface and bottom reflections while maintaining beam pattern quality without grating lobes. The new phase configuration fundamentally resolves the contradiction between minimizing harmful signal obstructions and preserving beam pattern integrity.
3Device complexity
If elements are grouped into four phases with 90-degree separation, then the array structure is simplified, but the beam angle cannot be reduced below 30 degrees
Solution Approach 1:
The patent segments the transducer array into six groups instead of four, with each group separated by 60 degrees in electrical phase. This segmentation approach maintains the systematic structure needed for phased array operation while providing the phase granularity required to achieve a 20-degree beam angle. The six-phase configuration balances structural organization with beam angle flexibility, resolving the contradiction between array structure simplicity and beam angle control capability.
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
The 20-degree beam angle configuration enhances profiling range, reduces signal obstruction, and minimizes spatial aliasing, while maintaining the benefits of phased array technology such as reduced size and immunity to local sound speed variations.
Implementation Method 1
the elements are grouped into staves which are separated in phase by 60 degrees, for a total of six distinct phases... the resulting transducer generates transmit and receive beams that are nominally inclined less than about 30 degrees from a planar normal axis of the array
Implementation Method 2
Acoustic Doppler Velocity Sensors (ADVSs)... measure velocity along lines of position defined by narrow acoustic beams
Data Source
AI summary
An acoustic transducer and method of generating acoustic transmit and receive beams is disclosed. The system includes a plurality of transducer elements arranged to form an array, where the elements are electrically connected into groups which operate at the same electrical phase, where the phases of adjacent groups of elements differ by between about 50 and 70 degrees and a beamforming circuit where the transmit and receive signals are operated with appropriate phase shifts to maintain the between about 50 and 70 degrees phase difference between adjacent groups. The resulting transducer generates transmit and receive beams that are nominally inclined less than about 30 degrees from a planar normal axis of the array.