Waveguide Probe Head with Concentrated Ohmic Resistors for Low Ripple
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Solution Overview
Problem
Existing probe heads with waveguides face challenges in achieving a smooth frequency response and low ripple in the transfer function, especially when dealing with high-frequency signals, due to the limitations of coaxial lines and complex production processes, which hinder flexible and comfortable adaptation at measuring points.
Innovation Solution
The use of a waveguide with a stripline containing multiple concentrated ohmic resistors distributed at fixed intervals, allowing for lengthening of the probe head with low ripple and favorable wave impedance, along with a passive splitter element and buffer amplifier for signal pre-amplification, reduces the demands on the measuring device and improves signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the bandwidth of the probe is increased, then the measurement capability is improved, but the probe tip must be made more compact which causes impedance transformation and signal destruction at high frequencies
Solution Approach 1:
A waveguide is introduced as an intermediary component between the probe tip and the measurement device. This waveguide serves as an extension cable that maintains high impedance and prevents signal destruction while allowing the probe tip to remain compact for high-frequency operation.
Solution Approach 2:
The probe system is divided into separate functional segments: a compact probe tip for high-frequency signal acquisition, a waveguide for signal transmission with controlled impedance, and a measurement device. This segmentation allows each component to be optimized independently for its specific function.
2Adaptability or versatility
If the probe tip is made longer to reach difficult measuring points, then adaptability is improved, but impedance transformation occurs at high frequencies causing signal destruction
Solution Approach 1:
The waveguide acts as an intermediary that decouples the physical length requirement from the electrical performance. The probe tip can be physically extended through the waveguide to reach difficult measuring points while the waveguide maintains controlled impedance to prevent signal destruction.
Solution Approach 2:
The solution transitions from a direct linear extension of the probe tip to a multi-dimensional structure where the waveguide provides physical extension in one dimension while maintaining electrical performance through controlled impedance design in another dimension.
3Loss of energy
If loss-free waveguides are used, then signal transmission is improved, but strong residual ripple remains in the transfer function
Solution Approach 1:
The waveguide is designed with specific impedance parameters and dimensional characteristics that control the transfer function. By carefully selecting the waveguide's physical dimensions and impedance values, the system achieves both low signal loss and reduced residual ripple in the frequency response.
4Manufacturing precision
If attenuated waveguides are used to reduce ripple, then frequency response is improved, but production of coaxial lines with strong homogeneous attenuation becomes complex
Solution Approach 1:
Instead of requiring homogeneous attenuation throughout the entire waveguide, the invention applies attenuation selectively in specific local regions. This localized damping approach reduces ripple in the frequency response while maintaining simplicity in the overall manufacturing process.
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 solution enables low-loss, low-coupling, and undistorted signal transmission with minimal ripple and low input capacitance, enhancing the quality of the measured signal while avoiding the complexity of coaxial cables and maintaining high-frequency properties.
Implementation Method 1
The at least one stripline contains a plurality of concentrated ohmic resistors, which are distributed at fixed intervals over the length of the stripline
Data Source
Figure 1~2
Figure 3a~3b
Figure 4
AI summary
The probe head comprises waveguides (33). One of the waveguides has a strip conductor. The strip conductor has multiple centered ohmic resistances (35). The centered ohmic resistances are divided in fixed distances over a length of the strip conductor. The size and distribution of centered ohmic resistances are positioned over a transfer function of the waveguide in one of the strip conductors. A resistive layer is provided, which is made from a nickel-chromium alloy.