Auxiliary Antenna for High-Altitude Radar Detection
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Solution Overview
Problem
Air traffic control radars have a 'cone of silence' above the horizon, which affects detection of high-altitude and maneuvering flights, as current antennas are not designed to handle targets beyond 50° elevation, leading to gaps in surveillance coverage.
Innovation Solution
A secondary radar system with a main antenna and an auxiliary beam antenna, featuring three radiation diagrams (sum, difference, and control), where the auxiliary antenna is inclined to maximize gain in the cone of silence, ensuring detection beyond 90° elevation, and coupling means adjust the radiation patterns for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional LVA antenna with cosecant-square radiation pattern is used, then the received signal level is constant for targets at constant altitude, but the antenna gain collapses at high elevations beyond 50°, creating a cone of silence
Solution Approach 1:
The antenna system is divided into two separate antenna devices: a main LVA antenna for low-to-medium elevation coverage and an auxiliary antenna for high-elevation coverage. Each antenna is optimized for its specific elevation range, with the auxiliary antenna specifically designed to provide gain in the 60°-90° elevation range where the main antenna fails.
Solution Approach 2:
The solution adds a spatial dimension by introducing an auxiliary antenna positioned and inclined at a different orientation than the main antenna. The auxiliary antenna is inclined at an angle between 10° and 30° relative to the vertical, allowing it to cover the high-elevation cone of silence that the vertically-oriented main antenna cannot reach.
2Power
If the antenna is designed for long-range enroute detection at low elevations, then the maximum gain is optimized for 5°-10° elevation, but the cone of silence becomes too large to cover high-altitude flights
Solution Approach 1:
The elevation coverage area is segmented between two antennas: the main LVA antenna handles low-to-medium elevations (5°-40°) where long-range enroute detection is needed, while the auxiliary antenna handles high elevations (60°-90°) for high-altitude flight coverage. This segmentation allows each antenna to be optimized for its specific elevation band without compromise.
Solution Approach 2:
Each antenna is given different local qualities optimized for its operational range. The main antenna maintains its cosecant-square pattern with maximum gain at 5°-10° for enroute detection, while the auxiliary antenna is specifically designed with beam-width and gain characteristics optimized for the 60°-90° elevation range, providing locally optimized performance in each zone.
3Reliability
If dual radar coverage is used to overcome the cone of silence, then high-altitude targets can be detected, but the system complexity and cost increase significantly
Solution Approach 1:
Instead of using two complete separate radar systems, the invention merges the high-elevation coverage function into the existing radar system by adding an auxiliary antenna device that works in conjunction with the main LVA antenna. The two antennas share the same radar transmitter and receiver, combining their coverage areas to provide complete spherical surveillance without requiring duplicate radar systems.
Solution Approach 2:
The auxiliary antenna is designed to be multi-functional, serving both as a high-elevation surveillance antenna and as part of the overall radar system architecture. It can operate independently for high-elevation targets while also potentially contributing to medium-elevation coverage, providing universal coverage across multiple elevation bands with a single antenna device.
Data Source
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AI summary
The radar is equipped with a main antenna (1, 12) having three radiation patterns, sum, difference and control, corresponding to said antenna (1, 12), said radar further comprises an auxiliary antenna device (41, 42), composed of an antenna (41) and a rear radiating element (42) located at the rear of said antenna (41), fixed above said antenna (1, 12) and coupling means, said auxiliary antenna device (41, 42): - having three radiation patterns, sum, difference and control, said control pattern being ensured for the direction opposite to the antenna (1) by said rear radiating element; - the antenna (41) being inclined to guarantee a maximum gain of its sum pattern in the elevation domain (60° - 90°).