Multifilar Antenna with Meandered Helical Elements
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Solution Overview
Problem
Existing dielectrically loaded multifilar antennas for circularly polarized radiation face challenges in efficiently operating across a wide range of frequencies above 200MHz, particularly in satellite communication services like GPS and S-band services, due to limitations in resonant frequency tuning and phase progression.
Innovation Solution
A dielectrically loaded multifilar antenna design featuring a conductive phasing ring with varying electrical lengths for resonant edges, coupled with helical radiating elements that deviate from pure helices to form sinusoidal paths, providing phase progression for circular polarization across multiple frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional dielectrically loaded multifilar antenna with uniform helical elements is used, then the antenna structure is simple and easy to manufacture, but it cannot achieve stable circular polarization across a broad frequency range above 200MHz
Solution Approach 1:
The patent applies local quality by varying the electrical lengths of different radiating elements through meandering. Specifically, elements are meandered to different extents so that their electrical lengths differ, with each element optimized for a specific frequency within the operating range. This local variation in element geometry enables broad frequency coverage while maintaining circular polarization, resolving the contradiction between frequency adaptability and structural simplicity.
Solution Approach 2:
The patent implements dynamics by introducing adjustable meandering parameters to the helical elements. The degree of meandering can be varied to tune the electrical length of each element, allowing the antenna to adapt its resonant characteristics across different frequencies. This dynamic geometric modification enables the antenna to maintain optimal performance across a broad frequency range without requiring multiple fixed-geometry antennas.
2Adaptability or versatility
If the radiating elements follow pure helical paths, then the antenna structure is simple, but the phase progression required for circular polarization cannot be maintained across multiple frequencies
Solution Approach 1:
The patent applies local quality by introducing meandering to specific portions of the helical elements rather than uniformly modifying the entire structure. The meandering is applied locally to adjust the electrical length and phase characteristics of individual elements, enabling precise control over phase progression across frequencies while minimizing overall structural complexity. This localized geometric modification allows circular polarization to be maintained across multiple frequencies.
3Adaptability or versatility
If the phasing ring has uniform electrical length, then the manufacturing is simple, but it cannot provide resonant characteristics at multiple operating frequencies
Solution Approach 1:
The patent applies local quality to the phasing ring by creating regions with different electrical lengths. The phasing ring is designed with varying path lengths from the feed point to different radiating elements, with each section optimized to provide the appropriate phase shift for its associated element. This local variation in phasing path length enables the single phasing ring to support multiple resonant frequencies, resolving the contradiction between manufacturing simplicity and multi-frequency resonance capability.
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 stable circular polarization and resonant characteristics across a broad frequency range, enhancing its performance in satellite communication services by optimizing the phasing ring and radiating element configurations.
Implementation Method 1
the electrical length of the outer edge is different to the electrical length of the inner edge such that the outer edge of the conductive track resonates at a first frequency of said plurality of operating frequencies, and the inner edge of the conductive track resonates at a second frequency of said plurality of operating frequencies
Implementation Method 2
a substantially cylindrical electrically insulative core made of a high relative dielectric constant material such as barium titanate
Implementation Method 3
at least four elongate generally helical conductive radiating elements located on the core
Data Source
AI summary
A dielectrically loaded antenna comprising an insulative core having proximal and distal surface portions and, between the proximal and distal surface portions, a side surface portion, a pair of feed nodes, a plurality of helical conductive radiating elements located on the core and, arranged between and coupling together the feed nodes and the radiating elements, a phasing ring, the radiating elements being coupled to the phasing ring, and further comprising a conductive linking element extending around the side surface portion, wherein a first group of radiating elements extends from the phasing ring over the core side surface portion to closed-circuit terminations on the linking element and a second group of elements extends from the phasing ring to open-circuit terminations on the said side surface portion which are spaced from the linking element, and wherein each of the elements of one of said groups is meandered about a respective pure helix.