Side Mounting MEMS Microphones on Tapered Horn Antennae
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Solution Overview
Problem
Microelectromechanical systems (MEMS) microphones experience signal attenuation when directly attached to vibrating surfaces due to the absence of a straight cylindrical tube and air cavity, leading to poor frequency response and signal-to-noise ratio.
Innovation Solution
Side mounting of MEMS transducers on tapered horn antennae via a perforation or hole in the sidewall, allowing for alignment and attachment of the MEMS microphone's port opening with the hole, which maintains sound pressure performance and reduces device height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the MEMS microphone is mounted at the throat of the horn, then the sound pressure performance is optimized, but the device height increases
Solution Approach 1:
The patent transitions from mounting the MEMS microphone at the throat (one-dimensional optimization along the horn axis) to mounting it on the sidewall (utilizing the second dimension radial to the horn axis). This dimensional change allows the microphone to be positioned laterally rather than axially, reducing the overall device height while maintaining acoustic performance through proper alignment of the microphone port with the horn's interior volume.
Solution Approach 2:
The patent introduces an intermediary structure (a tube or connector) that couples the MEMS microphone port to the horn's interior volume. This intermediary element allows the microphone to be mounted on the sidewall while still providing the necessary acoustic coupling to the horn's resonant volume, effectively mediating between the lateral mounting position and the acoustic requirements for optimal sound pressure performance.
2Length of stationary object
If the MEMS microphone is held directly against a vibrating surface, then the device profile is reduced, but the output signal is severely attenuated
Solution Approach 1:
The horn structure serves as an intermediary acoustic volume between the MEMS microphone and the vibrating surface. When the microphone is mounted on the sidewall, the horn's interior volume provides the necessary acoustic coupling, allowing the microphone to sense vibrations from the surface while maintaining signal amplitude. This intermediary volume prevents direct contact mounting attenuation while enabling a compact device profile.
Solution Approach 2:
The patent modifies the acoustic parameters by introducing the horn's resonant volume and tuning the dimensions of the sidewall opening and horn cavity. This parameter optimization ensures that the acoustic impedance matching is maintained even when the microphone is mounted on the sidewall rather than directly against the surface, preserving signal strength while achieving a low profile.
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 side mounting configuration maintains sound pressure performance at low frequencies and increases sensitivity at higher frequencies without degrading overall sound pressure, while reducing the device's length by approximately 33% compared to traditional throat mounting, enabling low-profile applications.
Implementation Method 1
The air volume associated with the physical dimensions of the tube opening and cavity in front of the MEMS microphone's port opening determines the inherent Helmholtz resonance of the system
Data Source
AI summary
Disclosed herein are implementations of devices and methods for side mounting of microelectromechanical systems (MEMS) transducers on tapered horn antennae. A hole may be made in a sidewall of a tapered horn antenna, where the hole may be substantially cylindrical, tapered and the like. In an implementation, an internal port opening of a MEMS microphone may be aligned with the hole and attached to the sidewall of the tapered horn antenna. In an implementation, the hole may be tapered with a diameter at one end the same or slightly larger than the diameter of the port opening of the MEMS microphone and a larger diameter at another end of the hole. In an implementation, a tube may be used to connect the internal port opening of the MEMS antenna to the hole in the tapered horn antenna. In an implementation, the tapered horn antenna may have multiple holes, each having its respective MEMS transducer.