Implantable Antenna Bandwidth via Slot-Loaded Conductive Plates
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Solution Overview
Problem
Implantable medical device antennas face challenges with narrow bandwidth, making them less effective across varying implant environments due to the variable nature of tissue properties and dimensions, which limits their efficiency in radio frequency telemetry.
Innovation Solution
The design incorporates a second conducting member with a full circle or polygonal cross-section, connected by strut-like first conducting members, which reduces the antenna's quality factor, thereby increasing bandwidth without adding physical length, and includes slots to ensure electrons take the longer path, enhancing electrical length without additional space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a narrow bandwidth antenna design is used, then the antenna structure is simple and manufacturing is easier, but the antenna effectiveness varies across different implant environments
Solution Approach 1:
The patent applies dynamics by making the antenna electrically adjustable through a varactor diode. The antenna's electrical length can be dynamically changed by varying the capacitance of the varactor diode, allowing the same physical antenna structure to adapt to different implant environments and tissue properties, thereby resolving the contradiction between structural simplicity and environmental adaptability.
Solution Approach 2:
The patent changes the electrical parameters of the antenna by incorporating a varactor diode that allows continuous adjustment of capacitance. This parameter change enables the antenna to tune its resonant frequency and electrical length, maintaining effectiveness across varying implant conditions without requiring multiple fixed-frequency antenna designs.
2Reliability
If the antenna electrical length is increased for better telemetry, then the bandwidth increases, but the physical device dimensions must be increased
Solution Approach 1:
The patent uses a serpentine configuration that folds the antenna into a compact three-dimensional layout within the header. This dimensional arrangement allows the antenna to achieve a long electrical length (lambda/4 at 403.5 MHz) while fitting within the constrained physical volume of the implantable device header, resolving the contradiction between telemetry efficiency and device size.
Solution Approach 2:
The patent employs a serpentine (curved/folded) antenna configuration instead of a straight linear arrangement. This curvature allows the antenna to pack more electrical length into a smaller physical footprint, achieving the required electrical length for reliable telemetry while maintaining compact device dimensions suitable for implantation.
3Manufacturing precision
If a fixed frequency resonant antenna is used, then the manufacturing precision requirements are lower, but the antenna bandwidth is narrow and less appropriate for varying implant conditions
Solution Approach 1:
The patent implements a dynamically adjustable antenna system using a varactor diode that can be electrically tuned after manufacturing. This eliminates the need for precise manual tuning during fabrication, as the antenna can be programmed to the correct frequency post-implantation, thereby maintaining low manufacturing precision requirements while achieving wide operational bandwidth and adaptability.
Solution Approach 2:
The patent enables post-manufacturing parameter adjustment through the varactor diode, allowing the antenna's resonant frequency and electrical characteristics to be modified electrically. This approach decouples manufacturing precision from operational performance, enabling the antenna to be manufactured with standard tolerances and then tuned to the precise frequency required for the specific implant application.
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 configuration results in a higher bandwidth antenna that improves the efficiency of radio frequency telemetry across different implant conditions, simplifies the production process, and reduces costs by allowing better automatic assembly and positioning during header production.
Implementation Method 1
the antenna is resonant at a frequency of 403.5 MHz
Implementation Method 2
a varactor diode is provided which changes an electrical length of the antenna
Data Source
Figure 1
Figure 2~4
Figure 5~7
AI summary
The present disclosure refers to a antenna for an implantable medical device with a broadened bandwidth comprising at least two strut-like first conducting members (2, 2', 32) wherein each adjacent pair of first conducting members is connected by a second conducting member (1, 31), wherein the second conducting member has the basic form of an at least partial round and/or polygonal plate or of at least a part of a sphere and/or polyhedron or a cross or a star, wherein the second conducting member further comprises at least one through going opening (3, 33), wherein the basic form fully encircles the opening.