Four-Port Transmission-Line Network for Signal Isolation
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Solution Overview
Problem
Current four-port transmission-line networks face challenges in efficiently isolating signals and combining/dividing power among ports, particularly in microwave systems, where existing solutions like rat-race couplers are limited by their two-dimensional structure and lack of phase control.
Innovation Solution
A four-port transmission-line network design featuring six transmission lines with specific connections and configurations, including capacitors and ferrite sleeves, to achieve balanced and differential signal handling, enabling effective signal isolation and combination/division with improved phase management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rat-race coupler is used for signal combination/division, then power distribution among ports is achieved, but phase control and signal isolation are limited due to two-dimensional structure
Solution Approach 1:
The patent transitions from a two-dimensional rat-race coupler structure to a three-dimensional configuration by introducing vertical stacking of transmission lines and multiple layers. This dimensional change enables improved phase control and signal isolation while maintaining power distribution functionality, directly resolving the limitation of the planar structure.
2Adaptability or versatility
If transmission line length is increased to improve frequency response bandwidth, then frequency coverage is expanded, but insertion loss increases
Solution Approach 1:
The patent divides the transmission path into multiple discrete transmission line segments or sections rather than using a single long transmission line. This segmentation allows for optimized impedance matching at each section, reducing reflections and insertion loss while achieving the desired wide frequency bandwidth through the combined effect of multiple sections.
3Manufacturing precision
If multiple transmission lines are added to improve power division accuracy, then power distribution precision is enhanced, but device complexity increases
Solution Approach 1:
The patent combines multiple transmission lines into a shared common node or junction structure where multiple lines converge. This merging approach enables accurate power division among multiple ports while reducing the total number of discrete transmission lines required, as the common node provides a shared reference point that simplifies the overall network topology.
Data Source
AI summary
In a four-port transmission-line network, a first transmission line is connected to a first port, second and third transmission lines are connected to a first component port, fourth and fifth transmission lines are connected to a second component port, and a sixth transmission line is connected to a fourth port. The transmission lines are connected as baluns to the ports with the unbalanced signal on the port side and the balanced signals interconnecting with others of the transmission lines. In another example, two or more baluns are connected serially. Each balun includes two transmission lines having signal-return conductors connected together at the ends. One end of a signal conductor on the first balun forms a sum port. One end of the signal-return conductors of the second balun forms a difference port, and a capacitor connects the other end of the signal-return conductors to circuit ground.