Conformal CPW Capsule Antenna for Dual-Band Wireless Endoscopy
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Solution Overview
Problem
Existing ingestible capsule endoscope antennas face challenges in achieving compact, efficient, and multi-band designs suitable for wireless communication within the constraints of a limited internal volume, often suffering from structural complexity, large dimensions, restricted bandwidth, and diminished gain.
Innovation Solution
A coplanar waveguide-fed conformal antenna system with an interdigital patch structure and notched ground plane is designed for dual ISM band operation, incorporating a parasitic radiator to enhance bandwidth and compactness, while addressing SAR and communication link performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional single-band or dual-band antenna designs are used in ingestible capsules, then the antenna can operate at specific frequency bands, but the antenna structure becomes complex and the physical dimensions increase
Solution Approach 1:
The patent implements a single conformal antenna structure that simultaneously supports dual ISM band operations at 0.915 GHz and 2.4 GHz. The antenna is designed with specific geometric parameters including a length of 31mm and width of 9mm, with feed line dimensions optimized for both frequencies. This universal design eliminates the need for separate antennas for different frequency bands, thereby reducing structural complexity while maintaining multi-band adaptability
Solution Approach 2:
The patent achieves multi-band operation by carefully controlling the physical dimensions and electrical parameters of the conformal antenna. The antenna length of 31mm and width of 9mm, along with specific feed line dimensions (width 3mm, gap 0.5mm), are optimized to resonate at both 0.915 GHz and 2.4 GHz. By adjusting these geometric parameters, the antenna supports multiple frequency bands without requiring complex multi-element structures
2Volume of moving object
If antenna size is reduced to fit capsule constraints, then the capsule internal volume is utilized efficiently, but the antenna bandwidth and gain are reduced
Solution Approach 1:
The patent employs a conformal antenna design that follows the curved inner surface of the cylindrical capsule. The antenna is wrapped around the capsule interior with a length of 31mm and width of 9mm, conforming to the capsule's curved geometry. This curved configuration allows efficient use of the limited capsule internal volume while maintaining adequate bandwidth and gain performance through optimized current distribution along the curved path
Solution Approach 2:
The patent transitions from a planar antenna layout to a three-dimensional conformal structure wrapped around the cylindrical capsule. By utilizing the curved surface area of the capsule interior, the antenna achieves effective radiation in a compact volume. The conformal wrapping allows the antenna to exploit the third dimension (curvature) to maintain electrical length and bandwidth while fitting within the constrained capsule dimensions
3Volume of moving object
If antenna size is reduced to fit capsule constraints, then the capsule internal volume is utilized efficiently, but the antenna gain is diminished
Solution Approach 1:
The conformal antenna design on the curved capsule surface optimizes the current distribution pattern to enhance radiation efficiency. The curved geometry with length 31mm and width 9mm creates favorable current paths that improve gain performance within the compact volume. The conformal structure ensures adequate separation from the capsule wall to maintain radiation efficiency while utilizing the available internal space
4Device complexity
If coplanar waveguide feed structure is used, then the antenna achieves compact dual-band operation, but electromagnetic interference with the battery occurs
Solution Approach 1:
The patent introduces a dielectric substrate as an intermediary layer between the coplanar waveguide antenna and the battery. The substrate with permittivity 2.2 and loss tangent 0.008, and thickness 0.254mm, serves as an electromagnetic barrier that isolates the antenna fields from the battery. This intermediary layer reduces electromagnetic interference and prevents detuning of the antenna resonance frequencies while maintaining the compact coplanar 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 antenna achieves dual-band operation at 0.915 GHz and 2.4 GHz with improved bandwidth and compactness, ensuring safe and efficient wireless communication within the human body, validated by in-vivo studies using a Wistar rat.
Implementation Method 1
the radiating patch, the ground strips, and the feed system are dimensioned and arranged such that current distribution along the antenna structure follows half guided wavelength paths
Implementation Method 2
The planar antenna structure is fabricated on a substrate of dimensions 9 millimeters by 31 millimeters, the substrate having a thickness of 0.254 millimeter, a relative permittivity of 2.2, and a loss tangent of 0.008
Data Source
AI summary
The present disclosure generally relates to a compact, conformal space-filling antenna system integrated within an ingestible capsule endoscope. The system utilizes a coplanar waveguide (CPW)-fed antenna, featuring a notched ground plane, a meandering radiating patch, and a parasitic patch, both designed in a serpentine pattern. This configuration enables operation at two distinct frequency bands: approximately 0.915 GHz with a 150 MHz bandwidth and 2.4 GHz with a 350 MHz bandwidth. The capsule houses a central processing unit for data transmission and sleep/wake-up functionality, powered by an internal battery. The antenna's conformal design maximizes space utilization within the cylindrical capsule, ensuring efficient wireless communication for medical diagnostic applications.