UAS Antenna Pattern Measurement With Aerostat Ground Isolation
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Solution Overview
Problem
It is challenging to perform free-space, three-dimensional far-field radiation pattern measurements of high-frequency antennas due to their large size and electrically large wavelengths, making traditional measurement techniques like anechoic chamber mapping impractical, and requiring alternative methods for accurate characterization.
Innovation Solution
The use of small unmanned aerial systems (sUAS) and helium-filled aerostats to elevate antennas above the ground, allowing for near-free space measurements by flying a sUAS with onboard RF measurement equipment to map the radiation patterns of high-frequency antennas, specifically employing a three-dimensional pattern and rotating the antenna to capture full radiation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional anechoic chamber mapping is used for high-frequency antennas, then measurement accuracy is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent uses an aerostat (balloon) as an intermediary platform to carry the antenna under test above ground level, eliminating the need for complex ground-based anechoic chambers. The aerostat serves as a mobile measurement platform that provides free-space conditions without requiring expensive fixed facility infrastructure, thus reducing device complexity while maintaining measurement accuracy.
Solution Approach 2:
The patent replaces the mechanical anechoic chamber structure with an aerodynamic solution (aerostat). Instead of using absorptive materials and complex chamber walls to achieve free-space conditions, the system uses atmospheric buoyancy and altitude to naturally provide free-space radiation conditions, simplifying the overall measurement system.
2Measurement precision
If antenna height is increased to minimize ground interactions, then measurement accuracy is improved, but supporting structure complexity increases
Solution Approach 1:
The patent uses aerostat buoyancy to counteract the weight of the antenna and supporting structure, eliminating the need for tall, complex mechanical support towers. The aerostat provides an upward buoyant force that balances the gravitational force on the antenna system, allowing the antenna to be positioned at high altitudes without requiring equally complex ground-based support structures.
Solution Approach 2:
The aerostat acts as an intermediary platform that carries the antenna above ground level, providing the necessary height to minimize ground interactions without requiring complex tall support structures. This intermediary platform uses atmospheric buoyancy to achieve elevation, simplifying the supporting structure requirements.
3Loss of information
If three-dimensional measurement patterns are implemented, then measurement completeness is improved, but measurement time increases
Solution Approach 1:
The patent uses a dynamic measurement approach where the aerostat moves through three-dimensional space to collect radiation pattern data from multiple positions and angles. Instead of using a static measurement setup that would require reconfiguring equipment for each measurement plane, the system dynamically captures complete spatial information during the aerostat's flight path, reducing total measurement time while maintaining data completeness.
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 method enables accurate, cost-effective airborne measurements of high-frequency antennas, minimizing ground interactions and providing reliable radiation pattern data, particularly for frequencies in the HF and VHF bands, as demonstrated by successful tests with dipole antennas.
Implementation Method 1
an aerostat and configured to suspend the first antenna at a height above ground
Data Source
AI summary
An unmanned, automated aerial system is programmed to fly in a set pattern around an antenna. The antenna is supported by a structure on the ground, or attached to an aerostat, according to its operational wavelength, in order to avoid ground effects. The radiation pattern of the antenna under test is measured by an antenna onboard the aerial system. The positional data of both antennas is logged to account for any interference in the measurements due to atmospheric conditions.