Compact Ultra-Broadband Antenna with Doughnut Radiation Pattern
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Solution Overview
Problem
Current omni-directional antennas exhibit elevation angle lobes and nulls, making 3D power-based geolocation challenging, and existing broadband antennas are either directional, expensive, or have large footprints, which are impractical for indoor use and high wind loads.
Innovation Solution
A compact, ultra-broadband antenna with a doughnut-like radiation pattern is designed using a pair of helmet-shaped antenna assemblies with hemispherical geometries on truncated cones, connected by a coaxial cable, which extends the impedance bandwidth and maintains azimuthal symmetry while minimizing elevation angle nulls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional broadband antennas (discone, biconical) are used to achieve wide impedance bandwidth, then the operating frequency range is extended, but the elevation angle pattern develops multiple lobes and nulls, and the antenna footprint increases
Solution Approach 1:
The antenna is divided into two distinct hemispherical assemblies positioned at opposite ends of a coaxial cable. Each hemisphere functions as an independent radiating element, and their combined effect produces a simplified elevation pattern without the multiple lobes and nulls that characterize conventional broadband antennas. This segmentation allows each element to contribute to a uniform omnidirectional pattern while extending the impedance bandwidth.
Solution Approach 2:
The invention transitions from planar or conical geometries to three-dimensional hemispherical structures. By positioning hemispheres at the ends of a coaxial cable along the vertical dimension, the antenna achieves a doughnut-like radiation pattern that maintains azimuthal symmetry while eliminating elevation angle nulls. This dimensional approach allows the antenna to maintain a simple elevation pattern across a wide frequency range.
2Shape
If biconical antennas are used to achieve broadband doughnut-like pattern, then the radiation pattern is simplified, but the antenna footprint and wind load increase
Solution Approach 1:
The two hemispherical assemblies are positioned at the ends of a coaxial cable, effectively nesting the radiating elements within a compact vertical structure. The coaxial cable serves as both the feed line and the structural support, allowing the hemispheres to be positioned close together while maintaining electrical isolation. This nested arrangement achieves a compact footprint compared to the large spread required by biconical antennas.
Solution Approach 2:
The hemispherical assemblies can be constructed using thin conductive materials or flexible shells, reducing the overall mass and wind loading while maintaining the required radiation characteristics. The hemispherical shape itself acts as a streamlined form that reduces wind resistance compared to the rigid, wide structure of biconical antennas.
3Shape
If dipole antennas are used to achieve simple doughnut pattern, then the elevation pattern is simplified, but the bandwidth is limited
Solution Approach 1:
The invention merges two hemispherical radiating elements positioned at opposite ends of a coaxial cable. Each hemisphere contributes to the overall radiation pattern, and their combined effect extends the impedance bandwidth while maintaining a simple doughnut-like elevation pattern. The coaxial cable structure provides a broadband feed mechanism that couples both hemispheres effectively across a wide frequency range.
Solution Approach 2:
The coaxial cable serves multiple functions: it provides the feed line for both hemispherical elements, acts as a structural support, and contributes to the overall resonance characteristics across a wide frequency range. This multi-functionality allows the antenna to achieve ultra-broadband operation while maintaining a simple geometric structure and doughnut-like radiation pattern.
Data Source
AI summary
A compact, ultra-broadband antenna with doughnut-like radiation pattern is provided as including a first assembly having first and second ends; a second assembly having first and second ends, the first and second ends each configured to have a substantially hemispherical shape; and a cable configured to extend through the first and second assemblies and out each of the first and second ends.