Tunable EM Chamber for Uniform Field Testing
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Solution Overview
Problem
Conventional TEM cells require multiple orientations and repeated measurements to fully characterize the EMC/EMI properties of electronic devices, as they generate EM waves with fixed polarization, failing to emulate the real-world EM wave environments effectively.
Innovation Solution
A compact reverberation chamber with tunable electromagnetic surfaces that allow dynamic 3D manipulation of EM field polarization, enabling uniform field distribution without the need to rotate the device under test, using phase shifting walls and varactor diodes to control surface impedance and wave propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional TEM cells are used to generate EM waves with fixed polarization, then the measurement process requires multiple orientations and repeated measurements, but this increases the testing time and complexity
Solution Approach 1:
The patent applies the dynamics principle by making the chamber walls electronically tunable rather than static. The phase shifting walls with variable surface impedance allow the EM field polarization and propagation characteristics to be dynamically adjusted during testing, eliminating the need for multiple physical reorientations of the DUT while maintaining complete EMC/EMI characterization capability
Solution Approach 2:
The patent implements parameter changes by controlling the surface impedance of the chamber walls through phase shifters and varactor diodes. By changing the electrical parameters (phase shift, surface impedance) of the walls, the system generates EM waves with different polarization states and propagation directions, enabling complete device characterization through parameter variation rather than physical reorientation
2Adaptability or versatility
If conventional TEM cells with fixed polarization are used, then the device structure is simple, but it fails to emulate the real-world EM wave environments effectively
Solution Approach 1:
The patent applies universality by designing the reverberation chamber to perform multiple functions: it can generate EM waves with any polarization state, control wave propagation directions, and simulate various real-world electromagnetic environments. The phase shifting walls enable the same chamber structure to emulate different environmental conditions (multipath, indoor, outdoor) without requiring separate testing apparatus for each scenario
Solution Approach 2:
The patent replaces mechanical reorientation systems with an electronic control system. Instead of mechanically rotating or repositioning the DUT or antennas, the system uses phase shifters and varactor diodes to electronically control the EM field characteristics, substituting a complex mechanical system with a more compact and controllable electronic system
3Ease of operation
If phase shifting walls with varactor diodes are used to enable dynamic 3D manipulation of EM field polarization, then complete EMC/EMI testing can be achieved without device reorientation, but the device complexity increases
Solution Approach 1:
The patent applies self-service by implementing automated control of the phase shifting walls and varactor diodes through a computer system. The testing process is self-managing, where the control system automatically adjusts the EM field parameters according to the testing requirements, eliminating the need for manual intervention or complex operator procedures while handling the increased device complexity through automation
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 solution allows for complete and efficient EMC/EMI testing without device reorientation, generating a uniform and pseudo-random EM field environment, reducing the size and complexity of the testing setup while meeting IEC standards for field uniformity.
Implementation Method 1
By controlling the activation of each tunable surface, the device of the present invention is able to control the wave propagation direction and tune the polarization inside the reverberation chamber in three dimensions
Implementation Method 2
employing a plurality of tunable electromagnetic surfaces to construct the walls of a reverberation chamber
Implementation Method 3
A reverberation chamber may artificially generate a random or pseudo-random EM field distribution inside of a chamber to mimic an actual multipath environment that electronic equipment may encounter
Implementation Method 4
reverberation chamber, which can generate uniform field distribution that mimics planar incident EM wave's in the real world
Data Source
AI summary
A method and apparatus provide an improved EM reverberation chamber which facilitates the dynamic three dimensional (3D) manipulation of EM field polarization within the chamber and produces a uniform field distribution inside the chamber. The chamber includes one or more walls with tunable lumped elements. A controller is provided to generate one or more control signals that are applied to the lumped elements and tunes their impedance in response to the one or more control signals. The result is to generate, within the chamber an electromagnetic field that appears to be random or pseudo-random in polarization, but which is sufficiently uniform in magnitude for EM testing.