Design of Planar Differential Microphone Array Beampatterns with Controllable Mainlobe Beamwidth and Sidelobe Level

Area of Science:

• Acoustic Signal Processing
• Array Signal Processing
• Beamforming Technology

Background:

• Differential beamformers are noted for frequency-invariant beampatterns, high directivity, and compact size.
• Designing differential beamformers for planar microphone arrays with small inter-element spacing presents unique challenges.

Purpose of the Study:

• To design differential beamformers with precise control over main lobe beamwidth and sidelobe levels.
• To develop beamforming solutions that mitigate white noise amplification and beampattern divergence issues.

Main Methods:

• Utilized Chebyshev polynomials to design desired beampatterns based on theoretical differential beamformer properties.
• Proposed null constrained and least square beamformers for planar arrays to approximate desired beampatterns.
• Deduced minimum norm and combined solutions to address low-frequency and high-frequency band limitations.

Main Results:

• Achieved precise control over main lobe beamwidth and sidelobe levels.
• Developed beamformers that approximate frequency-invariant beampatterns and allow steering without distortion.
• Introduced solutions that flexibly balance white noise gain, directivity, and beampattern distortion.

Conclusions:

• The proposed differential beamformers demonstrate significant properties and advantages for acoustic applications.
• The developed methods offer flexible solutions for optimizing beamformer performance across different frequency bands.
• Simulation results validate the effectiveness of the novel differential beamformer designs.