Stacked Waveguide Calibration Network for Phased Array Antennas
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Solution Overview
Problem
Conventional calibration networks for phased array antennas are complex, costly, and sensitive to external objects, requiring precise adjustments to maintain accurate signal amplitude and phase across antenna elements, which is challenging due to changes in ambient temperature and component characteristics.
Innovation Solution
A calibration network system utilizing vertically stacked rectangular waveguides with coaxial transmission lines, incorporating RF power dividers, phase shifters, and dummy loads to provide a compact and efficient method for calibrating phased array antennas, reducing complexity and sensitivity to external reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional calibration networks are used for phased array antennas, then calibration functionality is provided, but the system becomes complex, costly, and sensitive to external reflections
Solution Approach 1:
The patent extracts the calibration signal path from the main antenna radiation path by using a separate feed mechanism. The calibration signal is injected through a feed horn that couples to the waveguide without requiring the antenna elements to be part of the calibration network, thereby simplifying the overall system while maintaining calibration accuracy
Solution Approach 2:
The patent introduces an intermediary coupling mechanism between the calibration signal source and the antenna elements. The waveguide acts as an intermediary that distributes the calibration signal to multiple antenna elements without direct connection, reducing the complexity of the calibration network while maintaining signal integrity
2Measurement precision
If conventional calibration networks are used, then calibration is achieved, but the system requires precise adjustments to maintain accuracy under temperature changes
Solution Approach 1:
The patent segments the calibration network into modular components including separate waveguide sections, individual antenna element feeds, and distinct calibration signal injection points. This segmentation allows each component to be optimized for thermal stability independently, reducing the cumulative effect of temperature variations on overall system accuracy
Solution Approach 2:
The patent designs the waveguide and feed structures with specific geometric parameters that are optimized for thermal stability. The waveguide dimensions and feed horn characteristics are selected to minimize thermal expansion effects on signal propagation, maintaining amplitude and phase accuracy across temperature variations
3Measurement precision
If complex calibration networks are used, then calibration accuracy is maintained, but manufacturing cost and sensitivity to external objects increase
Solution Approach 1:
The patent extracts the calibration function from the main antenna radiation pattern by using a separate feed horn that couples energy into the waveguide system without requiring the antenna elements to radiate during calibration. This separation removes the calibration process from the radiation environment, eliminating sensitivity to external reflections while maintaining signal distribution accuracy
Solution Approach 2:
The patent creates a simplified copy of the signal distribution path specifically for calibration purposes. The waveguide feed system replicates the signal distribution function without using the actual antenna radiating elements, providing an accurate model for calibration that is isolated from external environmental factors
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
The system enables simple and reliable calibration of phased array antennas by minimizing the influence of external reflections and temperature changes, maintaining accurate signal distribution across antenna elements, thus ensuring consistent performance and reducing maintenance costs.
Implementation Method 1
A calibration network system utilizes vertically stacked rectangular waveguides with coaxial transmission lines
Implementation Method 2
The vertically stacked rectangular waveguides are spaced apart at a distance of about a quarter of a desired operating wavelength of the array antenna between centers of the rectangular waveguides
Implementation Method 3
portions of coaxial transmission lines that have a length of about a quarter of wavelength, thereby to provide a phase shift to the calibration signal of plus 90 degrees
Data Source
AI summary
A calibration network system for an array antenna and method for calibrating of the array antenna are described. The system includes a pair of rectangular waveguides stacked in parallel relation to each other and spaced apart at a distance of a quarter of an operating wavelength. The rectangular waveguides includes through-holes extending through a side-wall of the stacked rectangular waveguides from a bottom of a lower waveguide to a top of an upper waveguide to accommodate coaxial transmission lines. The side-wall has openings between the through-holes and an interior region of the rectangular waveguides in order to provide coupling of the coaxial transmission lines into the pair of rectangular waveguides. The system includes 90 degree phase shifter coupled to the upper rectangular waveguide, and a power divider/combiner coupled to a reference T/R Module, to the 90 degree phase shifter and to the lower rectangular waveguide.