Spiral EM Probe Absorbing Layer for Smooth Wideband Response
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electromagnetic (EM) probes for monitoring biological tissues face challenges in efficiently transmitting and receiving EM radiation across a wide frequency range, particularly in maintaining high efficiency at both lower and higher frequencies, and in achieving smooth transitions between bands.
Innovation Solution
The EM probe incorporates a spiral antenna with an EM radiation absorbing layer featuring concentric frame shaped regions, where the absorption coefficient increases as a function of distance from the geometric center or feeding point, optimizing energy absorption and reducing reflections to enhance bandwidth and polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional antenna design is used, then the structure is simple, but the bandwidth is limited and efficiency drops at extreme frequencies
Solution Approach 1:
The antenna is divided into multiple segments with different geometries (first antenna element, second antenna element, third antenna element) each optimized for different frequency ranges. This segmentation allows the antenna to maintain high efficiency across a wide bandwidth from lower to higher frequencies by having different segments dominate at different frequency ranges.
Solution Approach 2:
Different portions of the antenna are given different geometric properties and electrical characteristics. The first antenna element has a geometry optimized for lower frequencies, while the second and third elements have geometries optimized for higher frequencies. This local differentiation of properties allows the overall antenna to achieve wide bandwidth without requiring a completely complex redesign.
2Speed
If the antenna is optimized for lower frequencies, then lower cutoff frequencies are achieved, but efficiency at higher frequencies deteriorates
Solution Approach 1:
The antenna structure is segmented into multiple elements with different electrical lengths and geometries. The first antenna element provides the lower cutoff frequency determination, while the second and third antenna elements are specifically designed to maintain efficiency at higher frequencies. This segmentation resolves the contradiction by distributing frequency optimization across different segments.
Solution Approach 2:
The antenna system is designed to perform multiple functions across different frequency ranges simultaneously. The same antenna structure serves as both a lower frequency antenna (via the first element) and a higher frequency antenna (via the second and third elements), achieving universality in frequency operation without sacrificing efficiency at either end of the spectrum.
3Reliability
If the antenna is optimized for higher frequencies, then high efficiency is achieved, but lower cutoff frequencies increase
Solution Approach 1:
The antenna is segmented such that the first antenna element determines the lower cutoff frequency while the second and third elements optimize higher frequency efficiency. This segmentation allows independent optimization of different frequency ranges within a single antenna system, resolving the contradiction between lower cutoff frequency and higher frequency efficiency.
4Ease of manufacture
If a simple antenna structure is used, then manufacturing is easier, but frequency response smoothness and polarization quality deteriorate
Solution Approach 1:
Different local portions of the antenna are given different geometric and electrical properties to optimize specific aspects of performance. The first antenna element has properties optimized for lower frequencies and smooth frequency response, while the second and third elements have properties optimized for higher frequencies and circular polarization. This local quality differentiation achieves high manufacturing precision in frequency response without requiring complete structural complexity.
Solution Approach 2:
The antenna elements incorporate curved and spiral geometries (equiangular spiral, circular spiral) that inherently provide smooth frequency responses and improved circular polarization characteristics. These curved geometries, while more complex than straight lines, maintain manufacturing feasibility while significantly improving the smoothness of the frequency response and polarization quality.
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 design increases the effective bandwidth of the EM probe, allowing for lower cutoff frequencies with improved smoothness in the lower band while maintaining high efficiency in the higher band, and reduces interference effects, resulting in a more monotonic frequency response and improved circular polarization.
Implementation Method 1
The EM radiation absorbing layer has a plurality of substantially concentric frame shaped regions corresponding to portions of the spiral antenna having equal surface of antenna conductor, any of the plurality of concentric frame shaped regions has an EM radiation absorption coefficient greater than any other of the concentric frame shaped regions it encloses
Data Source
AI summary
An electromagnetic (EM) probe for monitoring at least one biological tissue. The EM probe comprises a spiral antenna conductor (not shown) and an EM radiation absorbing layer (92) mounted along the antenna. The EM radiation absorbing layer has a plurality of substantially concentric frame shaped regions (93A-C) corresponding to portions of said spiral antenna having equal surface of antenna conductor, any of said plurality of concentric frame shaped regions has an EM radiation absorption coefficient different than any other of said neighboring concentric frame shaped regions.