Directional Coupler Inductive Compensation Single-Layer Directivity
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Solution Overview
Problem
Conventional directional couplers with single-layer structures on printed circuit boards achieve only low directivity, and achieving more than 30dB directivity requires complex structures or individual optimization, while existing designs do not effectively superimpose signals to exploit interference.
Innovation Solution
A directional coupler with at least two coupled lines, three connections, and one inductance, where the second coupled line has a forward and reverse path connected to a common point with a series inductor, and a capacitance in parallel with the connection, forming an LC element, allowing for high directivity by optimizing the length and size of components to tune frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer structure on a printed circuit board is used, then the device complexity is reduced, but the directivity is limited to low levels
Solution Approach 1:
The patent changes the electrical parameters by introducing inductors and capacitors to create resonant circuits that compensate for the inherent limitations of single-layer structures. By tuning the resonant frequency of these added components, the directivity is enhanced without requiring complex multi-layer constructions.
Solution Approach 2:
The patent introduces inductors and capacitors as intermediary elements that mediate between the coupled lines to achieve signal interference control. These components act as mediators that enable the desired signal cancellation in reverse direction while maintaining forward signal transmission, thereby improving directivity in a simple single-layer structure.
2Device complexity
If signal superposition and interference are not exploited, then the circuit construction remains simple, but the directivity cannot exceed 30dB
Solution Approach 1:
The patent applies the principle of wave interference by creating resonant conditions in the coupled lines using inductors and capacitors. By tuning the resonant frequency, constructive interference occurs in the forward direction while destructive interference cancels signals in the reverse direction, achieving high directivity through signal superposition.
Solution Approach 2:
The patent modifies the electrical parameters of the coupled lines by adding reactive components (inductors and capacitors) that change the phase and amplitude relationships between signals. This parameter adjustment enables precise control over signal interference patterns to achieve directivity greater than 30dB.
3Manufacturing precision
If conventional structures with at least three layers are used, then directivity greater than 30dB can be achieved, but the device complexity increases significantly
Solution Approach 1:
The patent uses inductors and capacitors as intermediary elements that provide the necessary phase shifting and signal cancellation functions without requiring additional conductive layers. These discrete components achieve the same effect as complex multi-layer structures but with simpler single-layer implementation.
Solution Approach 2:
The patent achieves high directivity by changing the electrical parameters through added reactive components rather than changing the physical structure to multiple layers. The inductors and capacitors tune the resonant characteristics to provide signal interference control that would otherwise require complex multi-layer 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
This configuration achieves high directivity with minimal construction effort and ensures low attenuation in desired coupling directions, while undesirable coupling directions experience strong damping, enabling precise control over frequency response and directivity.
Implementation Method 1
A first inductor is connected in series with the reverse path
Implementation Method 2
The second inductance and the capacitance form an LC element
Implementation Method 3
at least two coupled lines, at least three connections and at least one inductance. A radio frequency signal is transmitted from the first coupled line to the second coupled line
Data Source
Figure 1
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AI summary
A directional coupler has at least two coupled lines (32, 33, 36), at least three connections (30, 37, 40, 42) and at least one inductance (38, 43). A radio-frequency signal is transmitted from the first coupled line (32) to the second coupled line (33, 36). The circuit is designed using stripline technology. The second coupled line (33, 36) in this case has a forward path (34, 35) and a backward path (39, 44) which are connected to a connection (37, 42). An inductance (38, 43) is connected in series with the backward path (39, 44).