Deployable Low-Frequency Radar Antenna for Low-Elevation Detection
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Solution Overview
Problem
Existing low-frequency radar antennas with horizontal antenna planes struggle to detect aircraft at low elevation angles or high altitudes due to reduced performance and limited detection range, requiring increased transmission power for angles greater than 45°, and are difficult to implement and mobilize due to their large size.
Innovation Solution
A low-frequency radar antenna with a light and flexible antenna plane that can be deployed perpendicular to the ground, using a lifting device like an aerostat to maintain the plane in an optimal configuration, compensating for wind effects and deformations, and featuring a network of elementary antennas with a radiating plane and ground plane connected by spacing crosspieces for improved detection capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the antenna plane is positioned horizontally on the Earth's surface, then the radar can operate with a stable platform, but the detection range is limited to a cone with 45° half-opening around the vertical normal direction
Solution Approach 1:
The patent rotates the antenna plane from horizontal to vertical orientation, changing the spatial dimension of the antenna array. This allows the radiation pattern to scan a much wider elevation range (from -90° to +90°) compared to the limited 45° cone available with horizontal positioning, thereby dramatically extending the detection range while maintaining platform stability on the ground.
Solution Approach 2:
The patent changes the orientation parameter of the antenna plane from horizontal (parallel to Earth's surface) to vertical (perpendicular to Earth's surface). This parameter change transforms the radiation pattern coverage from a limited conical region to a hemispherical or full-spherical coverage, enabling detection of aircraft at all elevation angles including low-altitude and high-altitude targets.
2Length of moving object
If the antenna points in directions close to parallel with the antenna plane to detect low-elevation aircraft, then the detection range increases, but the radiation pattern performance (power, beamwidth, directivity) degrades
Solution Approach 1:
By positioning the antenna plane vertically, the patent enables the main beam to point in directions that were previously impossible with horizontal positioning. The normal to the vertical antenna plane is horizontal, allowing the radar to illuminate low-elevation targets (near the horizon) while maintaining optimal radiation pattern performance, avoiding the performance degradation that would occur with horizontal antenna positioning.
Solution Approach 2:
The vertical orientation creates an asymmetric configuration relative to the traditional horizontal setup. This asymmetry allows the radiation pattern's optimal performance region to align with low-elevation detection requirements, where the main beam can naturally cover directions close to the horizon without compromising power, beamwidth, or directivity.
3Length of moving object
If the antenna array size is increased to extend detection range, then the detection capability improves, but the device becomes difficult to implement and mobilize
Solution Approach 1:
The patent achieves extended detection range not by increasing the physical size of the antenna array beyond practical limits, but by changing its orientation to vertical. This dimensional change allows a moderately-sized array to cover a much wider angular sector (full 360° azimuth plus all elevation angles), effectively extending detection range without proportionally increasing array dimensions or complexity.
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 detection of aircraft within a wider elevation range, including low-altitude and stealth aircraft, with improved detection properties and extended range compared to traditional antennas, without the need for pointing directions close to parallel with the antenna plane, and allows for easier mobility and deployment.
Implementation Method 1
using a lifting device like an aerostat to maintain the plane in an optimal configuration
Data Source
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AI summary
This low-frequency radar antenna (10), comprising an array of elementary antennae, capable of operating at a predefined operating frequency, is characterized in that it comprises a light and flexible antenna plane (12), the antenna plane comprising a radiating plane (22) and a ground plane (24), the radiating plane carrying the array of elementary antennas (34), the antenna plane being able to be deployed from a folded state to a deployed state, in which it adopts a conformation substantially perpendicular to the land or sea surface.