Hybrid Coupler Bandwidth via Segmented Transmission Lines
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Solution Overview
Problem
Conventional ring-hybrid couplers have limited bandwidth, performing poorly at frequencies below and above the center frequency due to their inherently inductive and capacitive characteristics, respectively, and attempts to enhance bandwidth, such as coiling the reversing line, often reduce thermal capability.
Innovation Solution
A hybrid coupler design with specific transmission line configurations, including λ/4 and λ/8 electrical lengths, and ungrounded signal-return conductors, which form a loop with series and reversed connections, providing improved operational bandwidth without the need for coiling, thus maintaining thermal capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional ring-hybrid coupler design is used, then the device is simple in structure, but the bandwidth is limited with poor performance at frequencies below and above center frequency
Solution Approach 1:
The transmission lines are segmented into multiple sections with different electrical lengths (λ/4 and λ/8 sections). This segmentation allows each section to contribute differently to the overall frequency response, enabling broadband operation by combining the characteristics of different length sections to maintain performance across a wider frequency range.
Solution Approach 2:
Different sections of the transmission lines are assigned different electrical lengths (λ/4 vs λ/8) to create local variations in electrical characteristics. This local differentiation allows specific sections to compensate for frequency-dependent effects, with shorter sections providing different impedance transformations than longer sections, thereby expanding the operational bandwidth.
2Adaptability or versatility
If the reversing line is coiled to enhance bandwidth, then the operational bandwidth increases, but the thermal capability is reduced
Solution Approach 1:
Instead of coiling the transmission line in three-dimensional space (which increases inductance and bandwidth but reduces thermal dissipation area), the patent achieves bandwidth expansion through electrical length variation in the planar dimension. By using λ/8 sections alongside λ/4 sections, the patent obtains the bandwidth benefit without the thermal penalty of coiled geometries.
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 design achieves a three-to-one operational bandwidth without coiling, enhancing performance across a broader frequency range while maintaining thermal efficiency compared to traditional approaches.
Implementation Method 1
A pair of conductive lines are coupled when they are spaced apart, but spaced closely enough together for energy flowing in one to be induced in the other
Implementation Method 2
energy flowing in one to be induced in the other
Data Source
AI summary
A hybrid coupler may include first, second, third, and fourth ports, and first, second, third, fourth, fifth, sixth, seventh, and eighth transmission lines. Each of the transmission lines may include a signal conductor inductively coupled to a signal-return conductor. The first, second, third, and fourth transmission lines may be connected together to form a loop with the first, second, and third transmission lines in series and the fourth transmission line twisted. The fifth, sixth, seventh, and eighth transmission lines may respectively connect respective junctions of the loop to the first, second, third, and fourth ports. A junction of the signal-return conductors of the first, fourth, and fifth transmission lines may not be directly connected to ground. Similarly, a junction of the signal conductor of the fourth transmission line and the signal-return conductors of the third and eighth transmission lines may not be directly connected to ground.