Antenna Phase Calibration via Sub-Multiple Frequency Signals
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Solution Overview
Problem
Current Traffic Collision Avoidance System (TCAS) installations are expensive due to the extensive cabling required for dual installations, which increases weight and cost, and existing methods for phase calibration of two-element arrays are not applicable.
Innovation Solution
A two-element array antenna system with frequency multipliers that transmit sub-multiple frequency signals for phase calibration, using a single transmission element per antenna, reducing the number of cables needed and enabling phase calibration without affecting regular system operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If four-element planar array antennas are used for TCAS installation, then bearing estimation capability is achieved, but the number of cables increases to eight total cables (four to top and four to bottom), resulting in considerable weight and expense
Solution Approach 1:
The patent divides the four-element planar array into two separate two-element arrays, with one array on the top surface and another on the bottom surface of the aircraft. Each two-element array requires only two cables instead of four, reducing the total cable count from eight to four while maintaining the bearing estimation capability through the combined use of both arrays.
2Measurement precision
If four-element planar array antennas are used for TCAS installation, then bearing estimation capability is achieved, but the number of cables increases to eight total cables, resulting in increased expense
Solution Approach 1:
The patent segments the antenna system into two independent two-element arrays, each requiring fewer cables and associated hardware. This segmentation reduces the overall material cost, installation complexity, and maintenance requirements while preserving the essential bearing estimation function through coordinated operation of both arrays.
3Manufacturing precision
If existing phase calibration methods for four-element arrays are used, then phase calibration is achieved, but these methods cannot be employed for phase calibration of two-element arrays
Solution Approach 1:
The patent modifies the phase calibration approach by transmitting calibration signals at a sub-multiple frequency and using frequency multipliers at each antenna element to generate the actual operating frequency. This parameter change in the calibration process enables phase calibration to be performed on two-element arrays using a method that can be adapted from four-element array calibration techniques.
Solution Approach 2:
The patent introduces frequency multipliers as intermediary devices at each antenna element that convert the sub-multiple frequency calibration signal into the actual operating frequency. This intermediary mechanism allows the calibration system to operate at a different frequency than the operating system, enabling phase calibration without interfering with normal TCAS operations and making the method applicable to two-element arrays.
4Manufacturing precision
If frequency multipliers are added to each antenna element for phase calibration, then phase calibration of two-element arrays becomes possible, but system complexity increases
Solution Approach 1:
The frequency multipliers are designed to serve dual functions: they operate during normal TCAS signal transmission and reception, and they also function during phase calibration by multiplying the sub-multiple frequency calibration signal. This multi-functionality reduces the need for separate calibration-specific hardware, thereby limiting the increase in system complexity while enabling phase calibration capability.
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 the number of cables required for TCAS installations from eight to four, lowering weight and cost while allowing for effective phase calibration of the antenna system.
Implementation Method 1
The antenna includes, for example, a frequency multiplier or mixer. The TCAS or system that requires phase calibration of the cables transmits a signal at a sub-multiple of the desired calibration frequency. The frequency multiplier at the antenna then generates the desired frequency.
Data Source
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AI summary
A two-element array antenna system includes a first antenna element (42) and a second antenna element (44). The first and second antenna elements respectively include first and second frequency multipliers (265, 270). A transmitting, receiving, and processing (TRP) system (49) is coupled to the first and second antenna elements via, respectively, a single first transmission element (52a) and a single second transmission element (52b). The TRP system is configured to transmit to the first antenna element a first input signal at a sub-multiple of a first frequency, receive from the first frequency multiplier a first calibration signal based on the first input signal, transmit to the second antenna element a second input signal at a sub-multiple of the first frequency, receive from the second frequency multiplier a second calibration signal based on the second input signal, and determine, based on the calibration signals, a relative phase difference between the first and second transmission elements.