RF Grounding Shims for Phased Array Antennas
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Solution Overview
Problem
As antenna arrays become smaller, achieving operating frequencies above 15 GHz is challenging due to difficulties in providing sufficient grounding contacts within the physical size limits, leading to RF leakage and crosstalk between radiating elements.
Innovation Solution
The use of conductive grounding shims with bumps and openings positioned between the PCB and the cover or pressure plate of the antenna, which function as ground contacts to reduce RF leakage and enable operation up to 50 GHz frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the physical size of the antenna array is reduced, then the antenna becomes more compact, but the ability to provide sufficient grounding contacts deteriorates
Solution Approach 1:
The grounding system is segmented into multiple discrete grounding contacts distributed across the antenna array substrate. Each radiating element is associated with dedicated grounding contacts, creating a modular grounding structure that maintains effectiveness in compact configurations.
Solution Approach 2:
Grounding contacts are strategically positioned in specific locations around each radiating element based on electromagnetic field distribution requirements. The grounding structure varies locally to optimize RF performance at different positions within the compact antenna array.
2Volume of moving object
If the feature sizes of components are reduced to fit smaller antenna arrays, then the antenna becomes more compact, but RF leakage between radiating elements increases
Solution Approach 1:
Grounding contacts serve as intermediary elements positioned between adjacent radiating elements to block RF leakage. These intermediate grounding structures prevent electromagnetic coupling between elements while maintaining the compact form factor.
Solution Approach 2:
The grounding structure is optimized locally around each radiating element with specific contact positions and dimensions tailored to prevent RF leakage in the immediate vicinity of each element, accounting for the compact overall size.
3Object-generated harmful factors
If grounding contacts are added to prevent RF leakage, then RF leakage is reduced, but the device complexity increases
Solution Approach 1:
The grounding contacts serve multiple functions simultaneously: they provide RF grounding, prevent leakage between elements, and serve as reference planes for impedance control. This multi-functionality reduces the need for separate structures for each function.
Solution Approach 2:
The grounding structure is merged with the antenna substrate and radiating element support structure, integrating multiple functions into a unified design rather than adding separate grounding components.
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 solution effectively reduces RF leakage and crosstalk between radiating elements, allowing the antenna array to transmit and receive signals at frequencies up to 50 GHz while maintaining reliable grounding, even in compact designs.
Implementation Method 1
one or more grounding shims (e.g., conductive sheets) configured to create ground contacts around a perimeter of each of the RF elements disposed on the PCB
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A method includes coupling a printed circuit board (PCB) and a first conductive sheet to a pressure plate to form an antenna sub-assembly. The first conductive sheet (110) defines a first plurality of openings (112) and includes a first plurality of bumps (212). At least one opening of the first plurality of openings is surrounded by a set of bumps of the first plurality of bumps. The method includes coupling the antenna sub-assembly to a cover to form an antenna assembly.