Dummy Load for High Power and Bandwidth via Segmented Design
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Solution Overview
Problem
Existing dummy loads for RF applications are not suitable for high frequencies and high powers, as they are prone to damage from overloads and lack effective shielding and matching properties, especially in Electromagnetic Compatible Chambers.
Innovation Solution
A dummy load design combining a resistive termination for low frequencies and a coaxial cable with varying cross section, arranged helically within a groove on a base plate, which compensates for the worsening matching properties of the resistive load with increasing frequency through frequency-dependent cable attenuation, providing robustness and broadband characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a resistive load is used for dummy load, then it can dissipate RF power at low frequencies, but the matching property deteriorates with increasing frequency
Solution Approach 1:
The dummy load is segmented into two functional parts: a resistive load for low frequency power dissipation and a coaxial cable for high frequency attenuation. This segmentation allows each component to optimize its performance in its designated frequency range, resolving the contradiction between power handling and matching quality across the full bandwidth.
Solution Approach 2:
The invention changes the parameter of cable attenuation by selecting a coaxial cable with specific attenuation characteristics (0.5 dB/m at 1 GHz). This parameter change enables the cable to provide frequency-dependent attenuation that compensates for the deteriorating matching of the resistive load at high frequencies.
2Reliability
If a coaxial cable is used for dummy load, then it can provide frequency-dependent attenuation for good matching at high frequencies, but the power dissipation capability is insufficient for high power applications
Solution Approach 1:
The dummy load is segmented into two functional parts: a resistive load for low frequency power dissipation and a coaxial cable for high frequency attenuation. This segmentation allows each component to optimize its performance in its designated frequency range, resolving the contradiction between power handling and matching quality across the full bandwidth.
3Power
If a resistive dummy load is used, then it can handle high power, but it lacks sufficient shielding attenuation for use in EMC chambers
Solution Approach 1:
The invention changes the parameter of cable attenuation by selecting a coaxial cable with specific attenuation characteristics (0.5 dB/m at 1 GHz). This parameter change enables the cable to provide frequency-dependent attenuation that compensates for the deteriorating matching of the resistive load at high frequencies.
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 solution enables the dummy load to handle high power and high bandwidth applications up to 10 GHz with good matching and shielding, while being robust against overloads and suitable for use in EMC Chambers, with effective heat dissipation and compact design.
Implementation Method 1
The electromagnetic signal, namely the electromagnetic wave, fed into the cable is attenuated by the cable attenuation value wherein the reflected portion is attenuated twice by the cable attenuation value. In general, the cable attenuation increases by the square root of the frequency
Implementation Method 2
a resistive termination acting as a resistive load for dissipating radio frequency power at low frequencies
Data Source
AI summary
A dummy load for high power and high bandwidth, the dummy load comprising a base plate, a resistive termination acting as a resistive load for dissipating radio frequency power at low frequencies, and at least one coaxial cable acting as a cable load for dissipating radio frequency power at high frequencies, the at least one coaxial cable being connected to the resistive termination. At least one of the resistive termination and the at least one coaxial cable is positioned on the base plate. The at least one coaxial cable has a cross section that varies over the length of the coaxial cable.