Compact Over-the-Air Test System Using Indirect Far-Field Reflectors
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Solution Overview
Problem
Current measurement systems for testing over-the-air characteristics of communication devices, particularly those using millimeter waves, require large volumes due to the nature of electromagnetic signals, necessitating a compact solution for reliable test results.
Innovation Solution
A compact measurement system utilizing multiple antennas and reflectors oriented at specific azimuth and elevation angles to create an indirect far-field test zone, independent of signal frequency, which emulates three-dimensional spatial channel models and compensates for frequency-dependent test volume issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large measurement system is used to generate test zones for mmWave signals, then reliable test results and acceptable measurement uncertainties are obtained, but the system volume becomes excessively large (greater than 10 m)
Solution Approach 1:
The patent transitions from direct far-field testing (requiring large linear distances) to indirect far-field testing using reflectors. By introducing a reflector dimension, the system creates a virtual far-field environment where the electromagnetic signals are reflected to simulate plane wave conditions, enabling compact measurement while maintaining test reliability
Solution Approach 2:
The reflector acts as an intermediary element between the antenna and the device under test. It mediates the electromagnetic signal transmission by reflecting the signals to create the required far-field test conditions, allowing the measurement system to achieve reliable results without requiring physically large distances
2Volume of stationary object
If multiple reflectors are used to create indirect far-field conditions, then the test volume is reduced and frequency independence is achieved, but the device complexity increases
Solution Approach 1:
The measurement system is segmented into multiple independent reflector units, each oriented at specific azimuth and elevation angles. This segmentation allows the complex function of creating three-dimensional spatial channel models to be divided into manageable directional components, reducing the overall system complexity while maintaining the compact test volume
3Adaptability or versatility
If directive beam steered antennas are used for mmWave communication, then the observed channel power angular spectrum and total angular spread are reduced, but the measurement precision requirements increase
Solution Approach 1:
The measurement system incorporates dynamic positioning capabilities for both the device under test and the measurement antennas. This dynamic adjustment allows the system to precisely track and measure the narrow beam patterns of directive antennas, maintaining high measurement precision while accommodating the adaptability requirements of modern mmWave communication systems
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
Enables reliable and frequency-independent testing of over-the-air characteristics in a compact setup, effectively reducing the test volume and allowing for accurate reproduction of power angular spectra and spatial channel models, even at high frequencies.
Implementation Method 1
The electromagnetic signal is reflected by one of the reflectors so that the electromagnetic signal corresponds to a planar wave, thereby providing indirect far-field conditions for testing
Data Source
AI summary
The present disclosure relates to a measurement system for testing a device under test over-the-air. The measurement system comprises a signal generation and/or analysis equipment, several antennas, several reflectors and a test location for the device under test. The antennas are connected with the signal generation and/or analysis equipment in a signal-transmitting manner Each of the antennas is configured to transmit and/or receive an electromagnetic signal so that a beam path is provided between the respective antenna and the test location. The electromagnetic signal is reflected by one of the reflectors so that the electromagnetic signal corresponds to a planar wave, thereby providing indirect far field conditions for testing. A first reflector of the several reflectors is orientated at a first azimuth angle and at a first elevation angle with respect to a center of the test location. A second reflector of the several reflectors is orientated at a second azimuth angle and at a second elevation angle with respect to the center of the test location. The second elevation angle is different to the first elevation angle. The second azimuth angle is different to the first azimuth angle. Further, a method of performing an over-the-air test of a device under test is described.