TEM Waveguide Coupling Structure for Antenna In-Band Testing
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Solution Overview
Problem
Conventional methods for testing the in-band amplitude-phase characteristics of antennas require high-calibration accuracy and specific test sites, such as microwave anechoic chambers, which are costly and difficult to manage, especially for temperature range testing.
Innovation Solution
A transmission absorbing structure and antenna in-band characteristics test system using a TEM waveguide formed by equivalent electric and magnetic walls, allowing for energy coupling with the antenna in a closed induction field area, eliminating the need for anechoic chambers and enabling self-calibration and temperature range testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional near-field or far-field methods are used for antenna testing, then in-band amplitude-phase characteristics can be obtained, but high requirements for test sites (microwave anechoic chambers) and complicated calibration processes are required
Solution Approach 1:
The patent extracts the essential function of anechoic chambers (electromagnetic wave absorption) and replaces it with a simplified calibration-free test structure consisting of a feed antenna and a standard antenna positioned at specific distances. This eliminates the need for complex anechoic chamber environments while maintaining measurement accuracy for in-band amplitude-phase characteristics.
Solution Approach 2:
The test system performs self-calibration by using the relationship between the feed antenna and standard antenna measurements. The system automatically determines the in-band characteristics through comparative measurement and calculation, eliminating the need for manual calibration procedures and reducing operational complexity.
2Measurement precision
If microwave anechoic chambers are used for antenna testing, then accurate measurements can be achieved, but the test sites are costly and difficult to manage, especially for temperature range testing
Solution Approach 1:
The patent removes the requirement for microwave anechoic chambers by using a different measurement approach based on near-field coupling and standard antenna comparison. This allows measurements to be performed in ordinary environments including temperature chambers, significantly improving ease of operation and reducing costs while maintaining measurement precision.
Solution Approach 2:
The patent changes the measurement parameters from far-field radiation patterns to near-field coupling coefficients. By measuring the coupling between the feed antenna and standard antenna at close distances, the system achieves accurate in-band characteristics without requiring anechoic chamber environments, enabling flexible temperature range testing.
3Measurement precision
If conventional test methods are used, then in-band characteristics can be measured, but the calibration process is complicated and calibration accuracy is poor
Solution Approach 1:
The system performs self-calibration by using the known characteristics of the standard antenna to automatically determine the feed antenna's in-band characteristics. The calibration process is integrated into the measurement procedure, eliminating separate calibration steps and improving both calibration accuracy and operational simplicity.
Solution Approach 2:
The standard antenna serves as an intermediary reference element that mediates between the feed antenna and the measurement system. By comparing the coupling characteristics with the standard antenna, the system achieves accurate calibration and measurement without requiring complex external calibration equipment or procedures.
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 provides accurate in-band characteristics testing with reduced electromagnetic leakage, no need for absorbing materials, and the ability to test antennas in a wide temperature range, improving calibration precision and site requirements.
Implementation Method 1
the coupling slots are configured for energy coupling with a to-be-tested antenna
Implementation Method 2
the two equivalent electric wall structures and the two equivalent magnetic wall structures are together configured to enclose the coupling feed structure, and form a transverse electromagnetic mode (TEM) waveguide
Data Source
AI summary
This application provides a transmission absorbing structure and an antenna in-band characteristics test system, relating to design of microwave antennas for radar and communication systems. The transmission absorbing structure includes a coupling feed structure provided with coupling slots for energy coupling with a to-be-tested antenna, two equivalent electric wall structures parallel to each other, and two equivalent magnetic wall structures parallel to each other. The two equivalent electric wall structures and the two equivalent magnetic wall structures together enclose the coupling feed structure, and form a transverse electromagnetic mode (TEM) waveguide. The system includes a vector network analyzer, a to-be-tested antenna electrically connected to the vector network analyzer, and a transmission absorbing structure.