Coax-Fed Spar Buoy Antenna for Mobile VLF/LF Coverage
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Solution Overview
Problem
Existing VLF and LF transmitters for command and control of submerged platforms are large and costly, with inefficient direct underwater signal transmission and limited coverage due to reliance on ionospheric propagation and massive monolithic structures.
Innovation Solution
A spar buoy system with a coaxial feed and antenna extending above the waterline, coupled with an energy storage and power generation subsystem below the waterline, allowing for distributed, low-power transmission using a conductive structure and aerial vehicle support for improved signal coverage and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large monolithic VLF transmitter structures are used, then signal transmission capability is improved, but system size and operational cost increase significantly
Solution Approach 1:
The invention divides the transmitter system into modular components: a buoyant platform, antenna assembly, power system, and control electronics. This segmentation allows the system to achieve VLF transmission capability without requiring a single massive structure, thereby reducing overall system size and deployment cost while maintaining signal transmission effectiveness.
2Device complexity
If direct underwater VLF transmission is used, then transmission path is simplified, but signal attenuation increases significantly
Solution Approach 1:
The invention uses the air-water interface as an intermediary transmission medium. The antenna transmits signals through the air above the water surface, leveraging the lower attenuation characteristics of air compared to water at VLF frequencies. This intermediary approach reduces signal attenuation while maintaining relatively simple transmission path architecture.
3Area of stationary object
If ionospheric propagation is used for VLF coverage, then areal communications coverage is improved, but signal interception becomes easier
Solution Approach 1:
The invention employs directional antenna elements and localized beamforming techniques to concentrate transmission energy in specific directional sectors rather than omnidirectional ionospheric propagation. This creates localized communication zones with improved coverage efficiency while reducing the overall broadcast area, thereby decreasing vulnerability to interception while maintaining adequate communications coverage for the intended operational area.
4Reliability
If massive transmitter infrastructure is deployed, then transmission reliability is improved, but mobility and adaptability are reduced
Solution Approach 1:
The invention employs a buoyant, mobile platform that can be deployed and repositioned as needed. The system includes stabilizing mechanisms and adjustable antenna elements that adapt to different sea conditions and operational requirements. This dynamic design maintains transmission reliability through active stabilization and signal processing while providing the mobility and adaptability needed for various deployment scenarios and locations.
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
Enables efficient, low-power VLF and LF signal transmission over a contained area without massive infrastructure, enhancing mobility and control of communication coverage while reducing power requirements and signal attenuation.
Implementation Method 1
a first portion of the spar buoy extending above a mean water line comprising a conductive structure comprising a coaxial feed, and an antenna coupled to the coaxial feed and extending above the conductive structure
Data Source
AI summary
A spar buoy for very low frequency (VLF) or low frequency (LF) transmission including a first portion of the spar buoy extending above a mean water line including a conductive structure including a coaxial feed, and an antenna coupled to the coaxial feed and extending above the conductive structure, and a second portion of the spar buoy below the mean water line including a transmitter coupled to the coaxial feed, an energy storage subsystem coupled to the transmitter and an electric power generation subsystem coupled to the energy storage subsystem.