RF Probe Coupler Wave Conversion and Phase Locking
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Solution Overview
Problem
Conventional RF measurement systems using probe couplers face issues with VNA error correction due to signals being proportional to voltage and current rather than waves, leading to ill-conditioned error correction and phase locking problems, especially when dealing with devices like short calibration standards and wide frequency ranges.
Innovation Solution
The solution involves converting sampled voltage and current signals into wave values using equations (an=(vn+inZ0)/2 and bn=(vn-inZ0)/2) to robustly apply VNA correction math, and using a separate power splitter for phase locking to maintain a constant signal, applicable to both VNAs and LSNAs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If probe couplers are used to sample voltage and current signals, then signal measurement is achieved, but VNA error correction becomes ill-conditioned and phase locking problems occur
Solution Approach 1:
The patent introduces a separate power splitter as an intermediary device to provide a constant signal for phase locking, decoupling the phase locking function from the probe coupler sampling system. This mediator resolves the conflict by providing a stable reference signal that doesn't suffer from the ill-conditioned error correction issues affecting the probe coupler measurements.
2Productivity
If probe couplers sample signals proportional to voltage and current, then real-time signal data is obtained, but the signals are not proportional to waves causing correction math problems
Solution Approach 1:
The power splitter acts as a mediator that provides a signal directly proportional to the wave, bypassing the need for complex transformations of voltage and current samples. This intermediary solution maintains real-time measurement capability while simplifying the error correction mathematics by providing appropriately scaled wave-proportional signals.
3Stability of the object's composition
If a constant signal is needed for phase locking, then measurement stability improves, but using the probe coupler signal causes phase locking problems due to signal proportionality issues
Solution Approach 1:
The patent uses a separate power splitter as an intermediary to provide the constant signal needed for phase locking. This mediator ensures both stability and accuracy by providing a signal that is inherently suitable for phase locking operations, avoiding the proportionality issues that plague probe coupler-based phase locking attempts.
Data Source
AI summary
A measurement system and method for conducting measurements on a device-under-test (DUT). The system includes, in one embodiment, a passive impedance controlling tuner, and a signal transmission line, the tuner including a signal transmission line segment as at least part of the signal transmission line. A signal coupling device is coupled in a non-contacting relationship to the signal transmission line between a signal port of the DUT and the tuner for sampling signals propagating between the passive impedance controlling tuner and the DUT to allow measurement of an actual impedance presented to the DUT with the DUT in place in the measurement system during measurement of DUT characteristics. Measurement system equipment receives response signals from the signal coupler. The measurement system is configured to conduct measurement of DUT characteristics without pre-characterizing the impedance controlling tuner.