Antenna Coupling Reduction via Conductive Stubs in Antennas-in-Package
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Solution Overview
Problem
RF devices face performance degradation due to electromagnetic coupling between closely arranged antennas, which limits miniaturization and increases noise interference, especially at high frequencies.
Innovation Solution
Incorporating conductive traces, or 'stubs', within the redistribution layer to trap energy and reduce unwanted coupling between antennas, while maintaining performance parameters like antenna gain and efficiency, by sizing and positioning these stubs to act as energy traps and adjust their length to specific wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If antennas are arranged closely to enable miniaturization, then device size is reduced, but electromagnetic coupling between antennas increases causing performance degradation
Solution Approach 1:
The patent introduces conductive traces (stubs) as intermediary elements positioned between the antennas to intercept and trap electromagnetic energy. These stubs act as mediators that prevent direct coupling between antennas by providing an alternative path for energy dissipation, thereby reducing harmful electromagnetic interaction while allowing close antenna spacing for miniaturization
Solution Approach 2:
The patent converts the harmful electromagnetic coupling energy into a beneficial effect by using conductive stubs to trap and dissipate this energy. The stubs are designed with specific lengths (odd multiples of quarter wavelength) to resonate at operating frequencies, transforming the problematic coupled energy into controlled energy dissipation that improves isolation between antennas
2Object-affected harmful factors
If conductive stubs are added to reduce coupling, then isolation between antennas is improved, but device complexity increases
Solution Approach 1:
The patent merges the conductive stubs with the existing redistribution layer structure, integrating the coupling reduction function into the already-present conductive planes. Rather than adding separate isolated elements, the stubs are formed as extensions or modifications of the redistribution layer conductors, combining multiple functions (power distribution, signal routing, and coupling reduction) into a unified structure
Solution Approach 2:
The conductive stubs serve multiple functions simultaneously: they act as energy traps to reduce coupling, provide additional grounding paths, and can be positioned to optimize both isolation and antenna performance. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity
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 solution achieves high isolation between antennas (less than -30 dB) at high frequencies, such as the 78 GHz band, improving signal-to-noise ratio and allowing for miniaturization without increasing package size, applicable in various RF devices including communication and sensing technologies.
Implementation Method 1
The conductive trace may be sized and positioned for trapping a portion of energy transmitted from the antenna
Data Source
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AI summary
A Radio Frequency (RF) device may include a plurality of antennas and one or more conductive traces configured to trap a portion of energy transmitted from at least one of the plurality of antennas. The one or more conductive traces are sized and positioned such that undesired coupling between the plurality of antennas may be suppressed while maintaining performance parameters of at least one of the plurality of antennas. The plurality of antennas and the one or more conductive traces may be formed using a redistribution layer coupled to a chip embedded in a molding layer.