Directional Coupler Layout for Accurate Wave Separation
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Solution Overview
Problem
Conventional directional couplers face challenges in accurately separating traveling waves and reflected waves due to the influence of impedance and magnetic field concentrations, leading to reduced directivity.
Innovation Solution
The directional coupler design includes a cross-shaped opening in the waveguide with elongated holes and a coupling line configuration that extends away from the waveguide axis, reducing the impact of magnetic field interference and increasing the separation accuracy between traveling and reflected waves by optimizing the intersection points and coupling positions of the transmission lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the coupling line is disposed close to the waveguide opening, then the coupling efficiency is improved, but the magnetic field interference increases and directivity deteriorates
Solution Approach 1:
The coupling line is intentionally positioned asymmetrically at a location that does not intersect the tube axis of the waveguide. This asymmetric displacement optimizes the balance between coupling efficiency and magnetic field interference rejection, achieving superior directivity by 5 dB or more compared to conventional symmetric configurations.
Solution Approach 2:
The invention extends the coupling line configuration into the spatial dimension outside the waveguide, with the line disposed at a position that fails to intersect the tube axis. This dimensional arrangement allows the coupling line to capture electromagnetic energy effectively while avoiding the concentrated magnetic field region at the waveguide opening.
2Measurement precision
If the transmission lines intersect the opening region, then the coupling strength is improved, but the separation accuracy between traveling and reflected waves deteriorates
Solution Approach 1:
The coupling line is extracted from the conventional configuration where it would intersect the opening region, and is instead disposed at a position that fails to intersect the tube axis. This extraction removes the harmful interaction with concentrated magnetic fields while preserving sufficient coupling capability through optimized positioning.
Solution Approach 2:
The coupling line acts as an intermediary element that mediates between the waveguide interior and the detection circuitry. By positioning it at a strategic location outside the waveguide that does not intersect the tube axis, it effectively couples the electromagnetic energy while avoiding direct exposure to high magnetic field regions, thus enabling accurate wave separation.
3Device complexity
If the opening is disposed at the tube axis position, then the structural simplicity is improved, but the directivity deteriorates due to magnetic field concentration
Solution Approach 1:
The opening and coupling line are deliberately positioned asymmetrically relative to the tube axis, with the coupling line disposed at a position that fails to intersect the tube axis. This asymmetric design, while slightly increasing structural complexity, achieves superior directivity by avoiding magnetic field concentration at the axis position.
Solution Approach 2:
Different regions of the waveguide structure are assigned different functional qualities: the tube axis region maintains its primary wave propagation function, while the offset position is optimized for coupling and detection. This local differentiation of functional qualities enables the coupling line to operate in a region with favorable electromagnetic characteristics for high directivity.
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 enhances the directivity by 5 dB or more, allowing for more accurate detection of traveling and reflected waves, approximately three times better than conventional couplers.
Implementation Method 1
The opening is disposed at a position failing to intersect the tube axis of the waveguide, and configured to emit circularly polarized microwaves
Implementation Method 2
The coupling line includes a first transmission line and a second transmission line which each intersect the opening in a plan view
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A directional coupler includes: an opening having a first and a second elongated hole, mutually-crossing at a position without intersecting a waveguide's axis in plan-view; and a coupling line having a first and a second transmission line that respectively include a first and a second intersecting-line portion. The first intersecting-line portion extends, from one end of the axis, away from the axis as approaching a perpendicular line, and intersects the first hole at a position farther away from the axis than the opening-cross portion is, the perpendicular line being orthogonal to the axis and passing through the opening-cross portion at which the first hole and the second hole intersect each other, in plan-view. The second intersecting-line portion extends, from another end of the axis, away from the axis as approaching the perpendicular-line, and intersects the second hole at a position farther away from the axis than the opening-cross portion is, in plan-view. The first and second transmission lines are mutually coupled at out of an opening-located region, in plan-view.