Millimeter Wave Antenna Air-Gap Layer Impedance Bandwidth
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Solution Overview
Problem
Designing antennas for millimeter-wave communications that achieve broad impedance bandwidth while meeting compact form factor, high directivity, adaptive beam steering, and low cost requirements is challenging, especially for devices operating under the WiGig protocol.
Innovation Solution
The antenna structure incorporates an air-gap layer with spacing elements such as solder balls or cavities between the radiating-element layer and the ground layer to increase impedance bandwidth, minimizing permittivity and thickness, and allowing for a separation that is less than 0.08 wavelengths, enabling efficient communication at millimeter-wave frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thicker substrate is used to increase impedance bandwidth, then the bandwidth is improved, but the overall antenna volume increases and fabrication becomes more complicated and costly
Solution Approach 1:
The patent extracts the dielectric substrate from the gap between the radiating element and ground plane, replacing it with an air-gap. This removes the problematic dielectric material that would increase volume and fabrication complexity while achieving the desired impedance bandwidth through the air-gap configuration.
Solution Approach 2:
The patent changes the permittivity parameter by replacing dielectric material with air (which has lower permittivity). This parameter change allows for increased impedance bandwidth while maintaining a compact form factor, as the air-gap provides the necessary electrical characteristics without the physical bulk of dielectric substrates.
2Reliability
If a thicker substrate is used to increase impedance bandwidth, then the bandwidth is improved, but fabrication becomes more complicated and costly
Solution Approach 1:
The patent removes the dielectric substrate from the gap structure, simplifying the fabrication process. The air-gap can be created through straightforward manufacturing techniques such as molding or spacing structures, avoiding the complex multi-layer dielectric stacking and alignment required for thicker substrate designs.
3Volume of moving object
If the separation between radiating element and ground plane is reduced for compact size, then the form factor is improved, but the impedance bandwidth is reduced
Solution Approach 1:
The patent changes the permittivity parameter by using air (lower permittivity) instead of dielectric material in the gap. This allows for reduced physical separation distance while maintaining or enhancing impedance bandwidth, as the lower permittivity compensates for the smaller gap size in the bandwidth calculation.
Data Source
Figure 1~2D
Figure 3~5B
Figure 6~7B
AI summary
Embodiments of millimeter-wave antenna structures are generally described herein. The antenna structure may include an a radiating-element layer comprising a patterned conductive material, a ground layer comprising conductive material disposed on a dielectric substrate, and a feed-line layer comprising conductive material disposed on a dielectric substrate. In some embodiments, the antenna structure may include an air-gap layer disposed between the radiating-element layer and the ground layer. The air-gap layer may include spacing elements to separate the radiating-element layer and the ground layer by a predetermined distance. In some other embodiments, the radiating-element layer may be disposed on a radiating-element dielectric substrate which may include one or more cavities between the radiating-element layer and the ground layer.