U-Shaped Wire Loop Coupler-Divider for Wideband Directivity
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Solution Overview
Problem
Existing directional signal couplers in microwave test setups for load pull measurements suffer from inferior directivity, especially in non-50Ω test environments, limiting their ability to accurately detect and isolate signal waves, which affects the validity of measurements and reconstruction of non-linear transistor responses.
Innovation Solution
A bi-directional signal coupler-divider is designed with a U-shaped electro-magnetic wire loop sensor integrated into a slotted airline or slabline, enhancing coupling and directivity by increasing capacitive currents, allowing for higher signal isolation and improved directivity, especially in wideband applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If commercial directional couplers are used in non-50Ω test environments, then the measurement setup is simple, but the directivity deteriorates significantly
Solution Approach 1:
The patent changes the physical parameters of the coupler by introducing a U-shaped electro-magnetic wire loop sensor with specific geometric dimensions (length, width, spacing) that are optimized for non-50Ω environments. This structural parameter change enables the coupler to maintain high directivity (exceeding 20 dB) when operating with non-50Ω terminations, whereas commercial couplers degrade to 10-20 dB directivity under the same conditions.
2Adaptability or versatility
If wideband performance is achieved using commercial couplers, then the frequency range is extended, but the directivity and coupling performance deteriorates
Solution Approach 1:
The patent applies local quality by creating non-uniform current distribution through the U-shaped wire loop sensor geometry. The loop is positioned at a specific location within the slotted airline with optimized dimensions (e.g., 0.5λ/4 to 1.5λ/4 length) that creates localized electromagnetic coupling. This localized coupling mechanism maintains consistent directivity and coupling performance across a wide frequency bandwidth, unlike commercial couplers that use uniform structures.
3Adaptability or versatility
If the coupled signal is split into detection and feedback ports, then the functionality is enhanced, but the device complexity increases
Solution Approach 1:
The patent merges the directional coupler and signal divider functions into a single integrated device. The U-shaped wire loop sensor naturally provides both the coupled port signal and the divided port signal through its geometry and positioning. This merging eliminates the need for separate coupler and divider components, reducing overall device complexity while enhancing functionality for simultaneous detection and feedback applications.
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 new coupler-divider achieves superior coupling and directivity, exceeding commercial couplers' performance, enabling more accurate signal detection and measurement in non-50Ω environments, and simplifies the test setup by integrating the coupler-divider within the tuner housing, enhancing the measurement of non-linear transistor behavior.
Implementation Method 1
A directional signal coupler-divider uses a slotted low loss transmission airline or a slabline... the strong concentration of electric field in the zone between signal conductor and close-by wire loop (FIG. 3) leads to higher induced electric currents, in the wire loop sensor
Implementation Method 2
the strong concentration of electric field in the zone between signal conductor and close-by wire loop (FIG. 3) leads to higher induced electric currents, in the wire loop sensor, which increases the coupled signal and decreases the isolated signal, thus increasing the coupling and directivity at the same time
Data Source
AI summary
Low loss high directivity signal couplers use one or two U-shaped wire loops inserted into a slot of a low loss transmission line; the low diameter coaxial cable ending in wire loop sensors, which are inserted into the slot of the transmission line lead to a coupled, an isolated and a divided port. High, capacitively induced, electrical current, because of the proximity between the signal conductor of the airline and the wire loop, compares favorably with the antiphase magnetically induced current component in the wire loop sensor and leads to increased coupling, division and directivity over a wide frequency range starting at a few hundred MHz and exceeding 18 GHz. The signal coupler-divider is used in hybrid load pull tuners with instantaneous vector signal measurement capability.