Concentric Quarter-Wavelength Coaxial Transformer Design
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Solution Overview
Problem
Existing coaxial characteristic-impedance transformers require a substantial length to achieve adequate bandwidth and low VSWR, leading to large physical dimensions and limitations in frequency range due to the series arrangement of λ/4 lines.
Innovation Solution
The λ/4 lines are arranged concentrically, allowing the outside conductor of one line to serve as the inside conductor of the next, and incorporating folding and compensating lines to maintain a compact size while increasing bandwidth, allowing electromagnetic waves to propagate through nested volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple λ/4 lines are arranged in series to achieve adequate bandwidth and low VSWR, then the transformation quality is improved, but the overall length of the transformer increases proportionally
Solution Approach 1:
The patent applies nesting by arranging multiple λ/4 lines concentrically, where the outside conductor of one line serves as the inside conductor of the next line. This nested configuration allows multiple transformation stages to be packed into a compact radial space, achieving the required transformation quality with significantly reduced overall length compared to series arrangement
Solution Approach 2:
The patent transitions from a one-dimensional series arrangement to a multi-dimensional concentric configuration. By utilizing radial spacing and allowing electromagnetic waves to propagate through nested volumes in opposite directions, the design achieves multiple transformation stages within a compact footprint, effectively adding spatial dimensions to the layout
2Adaptability or versatility
If the number of transformation stages is increased to achieve larger bandwidth, then the bandwidth is improved, but the physical dimensions of the transformer increase
Solution Approach 1:
The concentric nesting of multiple λ/4 lines enables increased bandwidth through additional transformation stages without proportionally increasing physical dimensions. Each nested line contributes to the overall transformation function, allowing the system to achieve wider bandwidth while maintaining a compact radial footprint
Solution Approach 2:
The patent combines multiple transformation stages into a single compact structure by making the outside conductor of one λ/4 line serve as the inside conductor of the next. This merging approach allows multiple functional stages to occupy the same radial space, increasing bandwidth capability without proportional increase in physical dimensions
3Length of moving object
If λ/4 lines are arranged concentrically to reduce overall length, then the compactness is improved, but the diameter may be constrained by folding requirements
Solution Approach 1:
The patent employs dynamic line folding where λ/4 lines are configured to fold back on themselves within the concentric structure. This allows the lines to accommodate the required electrical length while adapting to the radial geometry, managing the trade-off between compact length and diameter constraints through flexible routing
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
This configuration results in a shorter overall length and diameter, achieving a larger bandwidth and more uniform frequency-dependent reflectance factor, maintaining performance comparable to longer transformers with fewer stages.
Implementation Method 1
the λ/4 lines between the first terminal and the second terminals are at least partly disposed to surround each other concentrically... allowing electromagnetic waves to propagate through nested volumes
Implementation Method 2
each of which includes a coaxial line section having a mechanical length of approximately λ/4 (λ is the wavelength of the operating or center frequency)
Data Source
AI summary
A coaxial characteristic-impedance transformer for dividing RF power on a first terminal onto n second terminals situated in the same radial plane by multi-stage serial transformation via λ/4 lines is provided with a short overall size, where the λ/4 lines between the first connection and the second connections are at least partly disposed to surround each other concentrically.