Segmented RF Transmission Line for Low-Loading Antenna Routing
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Solution Overview
Problem
Current millimeter-wave antennas for electronic devices short-circuit or cause capacitive loading to the metal frame, deteriorating the performance of sub-6 GHz antennas and requiring additional volume, which is not aesthetically or mechanically desirable, especially with the trend towards larger displays.
Innovation Solution
A transmission line with a signal current line and at least one return current line, each comprising segments separated by dielectric gaps to minimize capacitive loading, allowing millimeter-wave antennas to be placed without affecting sub-6 GHz antenna performance, and enabling both types of antennas to share the same volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If millimeter-wave antennas are placed close to the metal frame, then the radiation opening can be smaller and the beam coverage is improved, but the antenna causes capacitive loading to the metal frame which deteriorates sub-6 GHz antenna performance
Solution Approach 1:
The transmission line is divided into multiple segments separated by dielectric gaps. The signal current line and return current line each comprise at least one first segment and at least one second segment, with aligned segments separated by dielectric gaps. This segmentation minimizes capacitive loading while maintaining transmission functionality.
Solution Approach 2:
Dielectric gaps are introduced as intermediary elements between the signal current line and return current line segments. These gaps act as mediators that reduce capacitive coupling and loading effects on the metal frame, allowing the transmission line to function without significantly affecting sub-6 GHz antenna performance.
2Reliability
If millimeter-wave antennas are placed far from the metal frame, then capacitive loading is reduced, but the radiation opening must be larger and beam coverage is limited due to shadowing
Solution Approach 1:
The transmission line is segmented with dielectric gaps that allow the line to extend through the antenna element with minimal capacitive loading. This enables the antenna to be positioned closer to the frame without the harmful loading effects, achieving compact volume while maintaining performance.
3Device complexity
If the transmission line uses conventional unbalanced design without dielectric gaps, then the structure is simpler, but the capacitive loading short-circuits the metal frame and deteriorates antenna performance
Solution Approach 1:
Both the signal current line and return current line are segmented with dielectric gaps. This balanced line design with gaps on both paths prevents short-circuiting through the return path, maintaining metal frame integrity and sub-6 GHz antenna performance.
Solution Approach 2:
Dielectric gaps serve as intermediary elements that electrically isolate segments of the transmission line, preventing direct capacitive coupling that would cause short-circuiting. This maintains the metal frame's electrical integrity while allowing the transmission line to function.
4Volume of moving object
If the capacitive coupling element antenna uses a smaller gap to the main body, then the device volume is reduced, but the antenna performance deteriorates
Solution Approach 1:
The transmission line is segmented with dielectric gaps that minimize capacitive loading onto surrounding structures. This allows the capacitive coupling element to maintain its required gap distance for optimal performance while the overall device volume is reduced through compact transmission line design.
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 minimizes common mode capacitance, reduces differential mode transmission loss above 10 GHz, suppresses out-of-band emissions, and allows for high-performance antennas, ensuring compliance with emission standards and efficient use of device space.
Implementation Method 1
each aligned first segment and second segment forming a capacitive coupling across the first dielectric gap
Implementation Method 2
aligned segments being separated by a first dielectric gap
Data Source
AI summary
A transmission line for transmitting radiofrequency range current between a first conductive element and a second conductive element, the transmission line comprising a signal current line and at least one return current line, the signal current line and the return current line(s) extending in parallel. Each current line comprises at least one first segment and at least one second segment. Each first segment is partially aligned with at least one adjacent second segment, aligned segments being separated by a first dielectric gap, and each aligned first segment and second segment forming a capacitive coupling across the first dielectric gap. This solution enables a transmission line which provides only small capacitive loading onto its surroundings, and which therefore can extend, e.g., through an antenna element without significantly affecting the performance of the antenna element.