Directional Antenna Array Omnidirectional Pattern Generation
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Solution Overview
Problem
Current antenna systems require separate directional and omnidirectional antenna arrays, increasing the number of antennas mounted on aircraft and complicating operations as both host and threat aircraft, necessitating a method to generate omnidirectional patterns from directional surveillance antennas.
Innovation Solution
Incorporating RF switches and a detuning network into the antenna array to decouple inactive elements, allowing a directional antenna to operate independently and produce an omnidirectional pattern without additional elements or mounting space, leveraging the antenna reciprocity theorem for both transmit and receive modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate directional and omnidirectional antenna arrays are used, then the directional surveillance function and omnidirectional transponder reply function are both satisfied, but the number of antennas mounted on aircraft increases and device complexity increases
Solution Approach 1:
The directional antenna array is designed to perform multiple functions: it provides directional surveillance patterns during host aircraft operations and can be switched to provide omnidirectional patterns during threat aircraft transponder reply operations. This multi-functionality eliminates the need for separate antenna arrays, reducing device complexity while maintaining adaptability.
Solution Approach 2:
The antenna array configuration is made dynamic through the use of switches and detuning networks that can reconfigure the antenna elements in real-time. The system transitions from a static directional configuration to a dynamic system that can switch between directional and omnidirectional patterns as needed, allowing a single array to fulfill multiple operational requirements.
2Adaptability or versatility
If separate directional and omnidirectional antenna arrays are used, then both transmission and reception functions are satisfied, but the mounting space and weight on aircraft increase
Solution Approach 1:
The invention merges the directional surveillance antenna array and the omnidirectional transponder antenna into a single integrated array. By combining these previously separate functions into one physical structure with reconfigurable elements, the total weight and mounting space requirements are significantly reduced while maintaining full operational flexibility for both host and threat aircraft modes.
3Adaptability or versatility
If directional antenna elements are activated for omnidirectional operation, then additional omnidirectional capability is achieved, but antenna asymmetry increases and pattern quality deteriorates
Solution Approach 1:
The detuning network extracts or removes the asymmetry-causing elements from the active radiation pattern during omnidirectional operation. By selectively detuning certain antenna elements through the network, the system eliminates their contribution to pattern asymmetry while maintaining their structural presence, thereby achieving a symmetric omnidirectional pattern from the directional array.
Solution Approach 2:
The system changes the electrical parameters (impedance, resonance frequency) of antenna elements dynamically using the detuning network. By adjusting these parameters, elements that would normally create asymmetry in directional mode are transformed to become electromagnetically inactive or symmetric during omnidirectional mode, thereby maintaining pattern quality across different operational modes.
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 approach reduces antenna asymmetry and adds an omnidirectional pattern to existing directional arrays without extra hardware, enhancing operational flexibility and reducing the number of antennas needed on aircraft.
Implementation Method 1
a feed network including a switch controller, a first RF switch, a second RF switch, and a detuning network electrically connected to the second antenna element and configured to transform an impedance of the second antenna element
Data Source
AI summary
An antenna system. The system includes a feed network with first input/output terminals and second output/input terminals, and antenna elements forming an array. In a first configuration: each of the second plurality of output/input terminals is connected to one of the antenna elements, the array operating according to a different radiation pattern based on which one of the first plurality of input/output terminals carries a signal into the feed network. In a second configuration: a selected antenna element is disconnected from the second plurality of output/input terminals and receives a direct signal, bypassing the feed network, and operates according to its independent radiation pattern. Also, in the second configuration each remaining antenna element is disconnected from the second plurality of output/input terminals and connected directly to a detuning network, causing these antenna elements to have a minimal effect on the independent radiation pattern of the selected antenna element.