Asymmetrical Yagi-Uda Antenna for Aircraft Radar Mapping
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Solution Overview
Problem
Conventional radar systems for terrain mapping face limitations in antenna size due to aircraft constraints, leading to reduced image quality and mutual interference issues when using multiple antennas for wider coverage.
Innovation Solution
The design features asymmetrical vertical and symmetrical azimuthal radiation patterns achieved by modifying the Yagi-Uda antenna layout, with directors positioned along a curved axis and fed by a compact balun, allowing for reduced ground radiation and increased bandwidth, enabling effective use on small to medium-sized aircraft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the antenna physical size is increased to improve image quality, then the mapping accuracy is improved, but the aircraft size requirements increase
Solution Approach 1:
The patent applies asymmetry by positioning the reflector at an angle of 45 degrees relative to the driven dipole, creating an asymmetrical Yagi-Uda antenna structure. This asymmetrical configuration produces a radiation pattern with enhanced gain in the azimuthal plane while maintaining compact physical dimensions suitable for small to medium-sized aircraft, thereby resolving the contradiction between mapping accuracy and aircraft size requirements
2Area of stationary object
If two antennas with beams pointing to sides are used to increase coverage width, then the terrain coverage is improved, but mutual interference between antennas increases
Solution Approach 1:
The asymmetrical Yagi-Uda antenna design with 45-degree reflector positioning creates a directional radiation pattern that concentrates energy in the azimuthal plane. This asymmetrical beam shaping allows for better spatial separation of signals from multiple antennas, reducing mutual interference while maintaining wide terrain coverage capability
Solution Approach 2:
The patent employs a curved boom structure to support the directors and reflector elements, creating a three-dimensional curved antenna geometry. This curvature optimizes the radiation pattern by directing beams more effectively across the terrain while minimizing side lobes that could cause interference between adjacent antennas in the array
3Device complexity
If conventional symmetrical radiation patterns are used, then the antenna structure is simple, but the ground radiation causes mutual interference
Solution Approach 1:
The patent introduces asymmetry through the 45-degree angled reflector positioning relative to the driven dipole, transforming the conventional symmetrical Yagi-Uda structure into an asymmetrical configuration. This modification redirects the radiation pattern to reduce groundward energy, minimizing mutual interference while maintaining structural simplicity
Solution Approach 2:
The patent applies local quality by specifically modifying the reflector positioning angle to 45 degrees, creating a localized asymmetrical feature in the antenna structure. This targeted modification at the reflector-dipole interface produces the desired radiation pattern optimization without requiring complete redesign of the entire antenna system
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 configuration enhances radar system performance by increasing antenna gain, reducing interference, and expanding the usable frequency range, resulting in improved mapping efficiency and reduced time required for area coverage.
Implementation Method 1
The use of radar waves to carry out such surveys is highly advantageous, since the propagation of electromagnetic waves in certain frequency ranges is not affected by weather conditions
Implementation Method 2
successive radar signals are emitted and returning echoes are received
Data Source
Figure 1~2
Figure 3~5
Figure 6(A)~8
AI summary
Asymmetrical three-dimensional radiating system composed by a modified Yagi-Uda (YU) antenna (10, 10'), whose asymmetrical radiating pattern in elevation is provided by a three-dimensional antenna structure. The structure is formed by the positioning of the parasitic elements (12a, 12b, 12c, 12d) progressively farther away from the antenna longitudinal axis (15), substantially horizontal, the parasitic elements position are located along a curved axis (18) with the said concavity facing down and whose proximal portion is tangent to the longitudinal axis (15) and the provision of a conductive material reflector plane. The antenna is fed through a microstrip balun (14), usually used in Quasi-Yagi antennas (QY).