Waveguide Transition Using Substrate Integrated Waveguide
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Solution Overview
Problem
The transition between microstrip and waveguide is sensitive to mounting accuracy, leading to significant signal attenuation due to mismatched characteristic impedances, with limited tolerance for lateral displacement.
Innovation Solution
A transition using a substrate integrated waveguide (SIW) as an intermediate component, which is less sensitive to positional displacements, and includes a ridge attached to the ceiling of the waveguide, with the characteristic impedance of the waveguide and SIW matched for maximum power transfer, and a solid metallic enclosure to screen spurious signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a direct transition between microstrip and waveguide is provided by means of a ridge arranged in the waveguide, then efficient signal transfer is achieved, but the transition becomes highly sensitive to mounting accuracy with limited tolerance for lateral displacement
Solution Approach 1:
The patent introduces a substrate integrated waveguide (SIW) as an intermediary component between the microstrip and the conventional waveguide. The SIW includes a ridge structure that provides a gradual impedance transformation, acting as a mediator that bridges the impedance mismatch between microstrip and waveguide while providing mechanical tolerance for mounting variations. This intermediary structure reduces sensitivity to lateral displacement while maintaining efficient signal transfer.
2Productivity
If the height of the ridge is gradually decreased during transformation into a rectangular waveguide, then efficient signal transfer from microstrip to waveguide is achieved, but the transition becomes sensitive to the mutual position of the ridge and microstrip
Solution Approach 1:
The transition structure is segmented into distinct sections: a microstrip section, a substrate integrated waveguide section with gradual ridge transformation, and a conventional waveguide section. This segmentation allows the impedance transformation to occur gradually across the SIW section, reducing the sensitivity to precise positioning while maintaining efficient signal transfer. The ridge height is gradually decreased across the SIW section rather than at a single interface.
3Device complexity
If a direct ridge waveguide transition is used, then a simple structure is obtained, but the mounting operation becomes complex due to high accuracy requirements
Solution Approach 1:
The substrate integrated waveguide serves as an intermediary that adds a moderate amount of structural complexity to the transition design, but this added complexity dramatically simplifies the mounting operation by providing tolerance for position variations. The SIW can be fabricated as an integrated circuit board structure, making it easier to manufacture and assemble compared to precision-machined ridge waveguide transitions.
Data Source
Figure 1
Figure 2a~2b
Figure 3a~4
AI summary
This invention relates to a transition between a microstrip and a waveguide, comprising a rectangular waveguide (102) having a floor (104), side walls (106), a ceiling (108), and a transition end; a microstrip (110); and a substrate integrated waveguide (112). At the transition end thereof, the rectangular waveguide is coupled to the substrate integrated waveguide at a first end of the substrate integrated waveguide. The microstrip is coupled to the substrate integrated waveguide at a second end thereof. The rectangular waveguide comprises a ridge (118) attached to the ceiling, extending along a portion of the rectangular waveguide, and having a first end portion which is engaged with a portion of a top surface of the substrate integrated waveguide at its first end.