Directional Coupler Narrow Wall Protrusion for Return Loss Reduction
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Solution Overview
Problem
Conventional directional couplers for high-frequency signals, such as microwaves and millimeter waves, experience increased return loss and reduced directivity at operation frequencies due to improper electric field distribution and coupling characteristics.
Innovation Solution
A directional coupler design featuring rectangular waveguides with a narrow wall having a protruding part that varies in width, where the protrusion amount is greater at the center than at the ends, to maintain optimal coupling and reduce return loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional directional coupler with uniform narrow wall is used, then the structure is simple, but return loss increases and directivity decreases at operation frequency
Solution Approach 1:
The narrow wall of the waveguide is designed with non-uniform thickness, where the thickness varies along the length of the wall. Specifically, the thickness is greater at the center portion and smaller at the end portions, creating localized variations in the electromagnetic field distribution that improve coupling characteristics and reduce return loss at the operation frequency
Solution Approach 2:
The thickness parameter of the narrow wall is changed along its length to optimize performance. By varying the thickness parameter from uniform to non-uniform distribution, the patent achieves better return loss and directivity characteristics at the operation frequency while maintaining the overall structural simplicity of the directional coupler
2Ease of manufacture
If the narrow wall thickness is uniform, then manufacturing is easier, but electric field distribution becomes improper causing increased return loss
Solution Approach 1:
Instead of requiring precise control of uniform thickness throughout, the patent applies local quality variation by making the narrow wall thickness non-uniform, with specific regions (center vs. ends) having different thicknesses. This approach is actually easier to manufacture as it tolerates natural variations in the forming process while achieving the desired electric field distribution
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 effectively reduces return loss and maintains directivity across the intended frequency range, ensuring proper operation of the directional coupler at the set operation frequency.
Implementation Method 1
Provision of the opening 731 in the narrow wall 73 enables the first rectangular waveguide 71 and the second rectangular waveguide 72 to be electromagnetically coupled with each other
Data Source
AI summary
In a directional coupler, a rectangular waveguide includes a second narrow wall and has a width varying part resulting from the second narrow wall protruding toward a first narrow wall, the width varying part including at least a portion of an opening, the protruding part protruding by a protrusion amount larger at the center of the width varying part than at both ends thereof.