Embedded PCB Termination Load for MM-Wave Surface Wave Absorption
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Solution Overview
Problem
Existing termination loads for millimeter-wave antenna arrays face challenges such as significant installation space, structural complexity, high production cost, and inability to operate at frequencies above 80 GHz, making them unsuitable for compact, reliable, and efficient antenna arrays with low side lobes and high efficiency.
Innovation Solution
A termination load embedded in a printed circuit board (PCB) comprising a feeding line, transitional patch, top resonator patch, and resistive material, which absorbs electromagnetic energy through electromagnetic coupling without conductive connections, allowing for compact and low-cost implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard resistors and terminators are used for termination loads, then parasitic radiation can be suppressed, but they cannot be used at extremely high frequencies (higher than 100 GHz) and require significant installation space
Solution Approach 1:
The patent replaces traditional mechanical/electrical termination components (standard resistors and lumped terminators) with an electromagnetic field-based solution. The termination load is realized through electromagnetic coupling between patches on different PCB layers, eliminating the need for physical resistors and their associated mounting hardware. This substitution enables operation at extremely high frequencies (above 100 GHz) while significantly reducing installation space.
Solution Approach 2:
The patent transitions from a two-dimensional planar arrangement of terminators to a three-dimensional embedded structure within the PCB substrate. By placing patches on different layers (first layer and second layer) and utilizing vertical electromagnetic coupling through the substrate, the solution achieves compact integration without compromising termination effectiveness at millimeter-wave frequencies.
2Reliability
If lumped terminators are placed on PCB surfaces, then termination function is achieved, but they cannot be implemented in inner layers due to extremely strong tolerances for 6G frequency band
Solution Approach 1:
The patent embeds the termination load structure within the multi-layer PCB substrate, nesting the functional elements (patches and coupling structures) inside the existing PCB architecture. The first patch is placed on the first layer, the second patch on the second layer, creating a compact nested arrangement that fits within inner layers without requiring additional outer-layer components. This nested configuration reduces the impact of manufacturing tolerances by distributing the termination function across multiple integrated layers.
3Ease of manufacture
If film resistors are used for termination loads, then they can be realized on ceramic substrates, but they cannot be realized for organic dielectric PCB substrates
Solution Approach 1:
The patent replaces the chemical deposition process required for film resistors with an electromagnetic field-based termination mechanism. Instead of applying resistive pastes through high-temperature processes, the solution uses electromagnetic coupling between conductive patches separated by the PCB substrate. This substitution eliminates substrate material constraints, allowing the termination load to be implemented on organic dielectric PCB substrates while maintaining ease of manufacture through standard PCB fabrication processes.
4Reliability
If passive elements with matched terminators are added to suppress surface waves, then radiation pattern is improved, but structure complexity and production cost increase
Solution Approach 1:
The patent merges the termination load function with the existing antenna array structure by integrating patches directly into the PCB layers that already contain antenna elements. The first and second patches are positioned adjacent to active antenna elements and share the same substrate and fabrication process. This merging eliminates the need for separate termination components and reduces overall structural complexity while maintaining radiation pattern quality.
Solution Approach 2:
The patent designs the PCB substrate and patch structures to serve multiple functions simultaneously: the same layers and materials that provide mechanical support and electrical connectivity for antenna elements also provide the termination load functionality. The electromagnetic coupling mechanism serves both as a transmission path and as a termination mechanism, eliminating the need for dedicated termination components and reducing production cost.
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 effectively absorbs parasitic surface waves, reducing side lobes and enhancing antenna array efficiency, reliability, and data transmission speed by converting electromagnetic energy into thermal energy.
Implementation Method 1
the excitation probe, the transitional patch and the top resonator patch are coupled to each other by electromagnetic coupling
Implementation Method 2
a gap between the top resonator patch and the top metal layer is filled with a resistive material
Implementation Method 3
The solution effectively absorbs parasitic surface waves, reducing side lobes and enhancing antenna array efficiency
Data Source
AI summary
An antenna array is provided that includes at least one active element and at least one passive element arranged around the active element. The passive element includes at least one feeding line disposed between a first ground layer and a second ground layer, a first patch located on the same plane as the first ground layer, and a second patch at least partially disposed between the feeding line and the first patch. The second patch is configured to be electromagnetically coupled to both the first patch and the feeding line. A radio-absorbing material is disposed adjacent to the first patch to improve electromagnetic performance.