Adjustable Wire-Loop Directional Coupler for Accurate Microwave Readings
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Solution Overview
Problem
Existing bi-directional signal couplers in microwave testing face challenges in maintaining accurate signal power readings due to dynamic range limitations, especially when dealing with high signal power differences between input and output, which can be mitigated by using adjustable couplers but often requires the use of attenuators that affect accuracy.
Innovation Solution
The implementation of a wire-over-ground (WOG) transmission line structure with a U-shaped electro-magnetic wire loop sensor and adjustable coupling control via deflection of the signal conductor, allowing for balanced signal power reading without attenuators, by maintaining the characteristic impedance and enhancing capacitive and magnetic coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If attenuators are added to balance signal power levels, then measurement accuracy is improved, but device complexity and insertion loss increase
Solution Approach 1:
The patent implements an adjustable coupling factor mechanism that allows the coupler to dynamically adapt its coupling ratio to match the dynamic range of the measurement instrument. By making the coupling factor variable rather than fixed, the system can optimize signal levels for different measurement conditions without adding external attenuators, thereby improving measurement accuracy while avoiding the complexity and losses associated with additional components
Solution Approach 2:
The patent changes the coupling parameter (coupling factor) of the directional coupler to optimize signal power distribution. By adjusting this parameter, the system balances the signal levels at different ports to match the dynamic range of measurement instruments, eliminating the need for external attenuators and their associated complexity and insertion losses
2Device complexity
If fixed coupling factor is used, then device complexity is reduced, but adaptability to different signal power levels deteriorates
Solution Approach 1:
The patent transforms the static coupling factor into a dynamic, adjustable parameter. The coupler can now adapt its coupling ratio to match different signal power levels and instrument dynamic ranges, providing versatility without significant complexity increase through the use of adjustable mechanical or electrical control mechanisms
Solution Approach 2:
The adjustable coupling factor mechanism enables the single coupler device to serve multiple measurement conditions and signal power levels. By incorporating adjustment capability, the coupler becomes a universal component that can optimize performance across various measurement scenarios rather than requiring multiple fixed-coupling devices
3Measurement precision
If attenuators are used to balance signal levels, then measurement accuracy is improved, but signal loss increases
Solution Approach 1:
The patent extracts and removes the external attenuators from the measurement system by incorporating the coupling adjustment capability directly into the directional coupler. This eliminates the need for separate attenuating components, thereby removing their associated insertion losses while maintaining the ability to balance signal levels for accurate measurement
Solution Approach 2:
By changing the coupling factor parameter of the directional coupler, the system achieves signal level balancing without the energy loss inherent in attenuators. The adjustable coupling mechanism redistributes signal power internally within the coupler structure, avoiding the dissipative losses that occur when signal power is intentionally reduced through attenuating components
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 approach achieves superior coupling and directivity, enabling precise control of the coupling factor and maintaining measurement accuracy across a wide frequency range without the need for attenuators, thus improving the sensitivity and reliability of microwave measurements.
Implementation Method 1
enhancing capacitive and magnetic coupling
Implementation Method 2
enhancing capacitive and magnetic coupling
Implementation Method 3
wire-over-ground (WOG) transmission line structure
Data Source
AI summary
A simple low-loss high-directivity wire coupler uses a wire over ground transmission airline structure and the center conductor of a folded low diameter coaxial cable ending in a wire loop sensor, which is inserted into the ground wall of the transmission line, branching into a coupled and an isolated port. The coupling factor is adjustable by laterally displacing the conductor of the transmission line in the area of the sensor without affecting the characteristic impedance. Directivity and residual reflection are maintained. Higher, capacitively induced, electrical current, because of the confined zone between signal conductor and ground wall, compares favorably with the antiphase magnetically induced current component in the wire loop sensor and leads to increased coupling and directivity over a frequency range up to at least 70 GHz.