Slidable Choke Microwave Antenna for Impedance Matching
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Solution Overview
Problem
Conventional microwave antennas have a narrow operational bandwidth, leading to impedance mismatch as tissue dielectric properties change during treatment, resulting in inefficient energy delivery and structural integrity compromises during insertion.
Innovation Solution
A microwave antenna assembly with a slidable outer jacket and a coolant fluid system that maintains impedance matching by buffering wavelength variations and providing structural integrity, featuring a dipole antenna with a trocar and fluid feed members for efficient energy delivery and insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional microwave antennas are used, then the antenna structure is simple, but the operational bandwidth is narrow causing impedance mismatch as tissue dielectric properties change
Solution Approach 1:
The patent applies the dynamics principle by making the outer jacket slidable along the antenna shaft, allowing it to move between extended and retracted positions. This dynamic adjustment changes the electrical length of the antenna system, enabling impedance matching across varying tissue dielectric conditions. The outer jacket transitions from a static protective cover to a dynamic tuning element that adapts to changing operational conditions.
Solution Approach 2:
The outer jacket serves multiple functions: (1) as a protective cover during insertion, (2) as a structural support element, and (3) as a可调 impedance matching element during operation. By integrating these diverse functions into a single component, the design achieves broad adaptability without proportionally increasing complexity.
2Strength
If the outer jacket is extended to provide structural support, then structural integrity during insertion is improved, but the radiating portion is obscured reducing energy delivery efficiency
Solution Approach 1:
The outer jacket is designed to dynamically change position between an extended state during insertion (providing structural support and protection) and a retracted state during operation (exposing the radiating portion for efficient energy delivery). This temporal separation of functions resolves the contradiction between needing structural support and needing exposed radiating elements.
Solution Approach 2:
The antenna system is segmented into distinct functional zones: the outer jacket (protective/support structure), the shaft (transmission element), and the radiating portion (energy delivery element). This segmentation allows each component to optimize its specific function while minimizing interference with other components.
3Strength
If the outer jacket is made rigid to maintain structural integrity, then ease of insertion is improved, but the ability to slide and adjust for impedance matching is reduced
Solution Approach 1:
The outer jacket exhibits different mechanical properties at different locations: the distal portion (tip) is made rigid to provide structural support and protection during insertion, while the proximal portion is made flexible to enable sliding movement along the shaft. This spatial variation in mechanical properties allows the single component to satisfy both structural and operational requirements.
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 ensures consistent impedance matching and effective energy delivery, maintaining structural integrity during insertion and treatment, allowing for targeted and efficient ablation with reduced power dissipation zones and faster ablation times.
Implementation Method 1
The outer jacket is made from a conductive material and acts an electrical termination choke. The outer jacket is configured to slide about the radiating portion and the feedline from a closed configuration, in which the outer jacket is mated with the trocar, to a retracted configuration, in which the outer jacket is retracted proximally to expose at least a portion of the radiating portion.
Implementation Method 2
In monopole and dipole antennas, microwave energy radiates perpendicularly from the axis of the conductor. A dipole antenna may have a coaxial construction including an inner conductor and an outer conductor separated by a dielectric portion.
Implementation Method 3
Microwave energy is used to coagulate and/or ablate tissue to denature or kill the cancerous cells.
Implementation Method 4
Various improvements have been disclosed in the art, which aid in maintaining proper tuning of the antenna during use as the tissue is treated. However, these improvements tend to compromise the structural integrity of the antennas.
Data Source
AI summary
A microwave antenna assembly is disclosed. The antenna assembly includes a feedline having an inner conductor, an outer conductor and an inner insulator disposed therebetween and a radiating portion including a dipole antenna coupled to the feedline and a trocar coupled to the dipole antenna at a distal end thereof. The antenna assembly also includes a slidable outer jacket disposed about the radiating portion and the feedline. The slidable outer jacket being configured to slide about at least one of the radiating portion and the feedline from a closed configuration, in which the slidable outer jacket is mated with the trocar and a retracted configuration, in which the slidable outer jacket is retracted in a proximally exposing at least a portion the radiating portion.