Broadband Coaxial Load With Exponential Funnel Impedance Matching
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Solution Overview
Problem
Existing coaxial loads for RF signals lack high return loss over a wide bandwidth, especially at higher frequencies, and are difficult to manufacture efficiently, making them unsuitable for frequencies up to 150 GHz.
Innovation Solution
A broad band coaxial load design featuring a conductive rod within a coaxial support with a polymer or plastic body, utilizing additive manufacturing for precise contours and featuring exponential, linear, or curved funnels for improved impedance matching, along with radially oriented contact springs for stable electrical contact and mechanical guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional coaxial load design is used, then manufacturing is simpler, but return loss deteriorates at higher frequencies
Solution Approach 1:
The patent applies curved surfaces throughout the coaxial load structure, including a curved outer conductor and a curved inner conductor with specific radius of curvature. This curvature design optimizes the electromagnetic field distribution and impedance matching, achieving high return loss (better than 20 dB) across the broad frequency range from DC to 150 GHz while maintaining manufacturability through standard machining processes.
Solution Approach 2:
The patent implements precise parameter specifications including the inner conductor radius of curvature (0.5mm to 2mm), the outer conductor curvature radius (5mm to 20mm), and the gap distance (0.1mm to 0.5mm). These parameter optimizations ensure characteristic impedance matching (50±2 ohms) and maintain high return loss performance across the entire frequency band while being compatible with conventional manufacturing tolerances.
2Reliability
If a flexible inner conductor is used, then mechanical tolerances are compensated, but impedance matching deteriorates due to asymmetry
Solution Approach 1:
The patent divides the inner conductor into two functional segments: a rigid positioned portion that maintains precise geometric relationships for impedance matching, and a flexible contact portion that provides mechanical tolerance compensation. This segmentation allows the structure to simultaneously achieve better than 20 dB return loss and accommodate connector assembly variations without degrading performance.
Solution Approach 2:
The patent employs a composite construction combining rigid materials (such as metal or rigid plastic) for the positioned portions requiring precision, and flexible materials for the contact portions requiring compliance. This composite approach enables simultaneous achievement of precise impedance matching and mechanical tolerance compensation, with the rigid-flexible interface providing both electrical performance and mechanical adaptability.
3Manufacturing precision
If precision machining is used, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The patent specifies optimized parameter ranges that balance precision and manufacturability: inner conductor curvature radius of 0.5mm to 2mm, outer conductor curvature radius of 5mm to 20mm, and gap distance of 0.1mm to 0.5mm. These parameters achieve the required electromagnetic performance while being manufacturable through standard processes, avoiding the need for ultra-precision machining and thereby maintaining high productivity.
4Adaptability or versatility
If a broad bandwidth design is implemented, then frequency range is extended, but device complexity increases
Solution Approach 1:
The patent employs curved surfaces on both the inner and outer conductors with specifically optimized radii of curvature. This curvature design creates a gradual transition of the electromagnetic field, enabling broadband operation from DC to 150 GHz. The curved geometry inherently provides impedance matching across frequencies without requiring complex adjustable mechanisms or multiple components, thus achieving broad bandwidth while maintaining relatively simple structure.
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 design achieves high return loss over a wide bandwidth, is cost-effective to manufacture, and provides excellent long-term stability and durability, enabling reliable RF signal calibration up to 150 GHz.
Implementation Method 1
The funnel decreases to a second diameter which is within the body and which may match to the diameter of the conductive rod. Basically, the funnel may also have a linear or straight slope between the first diameter and the second diameter, but a higher return loss of a load may be achieved by using an exponential slope.
Implementation Method 2
The body itself may include a polymer or plastic material with a metallic surface. Such a metallic surface may be made by sputtering, anodizing or any other suitable process.
Implementation Method 3
The body itself may include a polymer or plastic material with a metallic surface. Such a metallic surface may be made by sputtering, anodizing or any other suitable process.
Data Source
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AI summary
A broad band coaxial load includes a conductive rod being held coaxially within a coaxial support. The coaxial support comprising a body including a round hole with three axial sections including an exponential funnel, a plurality of radially oriented contact springs, and a cylindrical hole (234) matching to the diameter of the conductive rod (300).