Near-Field OTA Measurement of RIS Reflection Patterns
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Solution Overview
Problem
Existing methods for testing reconfigurable intelligent surfaces (RIS) in wireless communication require large spatial setups and additional equipment, leading to high manufacturing costs and inefficient use of resources.
Innovation Solution
An over-the-air (OTA) measurement system that utilizes a positioner unit to hold the RIS in adaptable positions, with RF antennas positioned in the near-field region to transmit and receive signals, and an analysis circuit to determine a corrected equivalent source, reducing spatial requirements and eliminating the need for additional components like reflectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bistatic antenna OTA measurement system with feed antenna and probe antenna in far-field region is used, then beamforming capabilities of RIS can be tested, but spatial requirements become rather large
Solution Approach 1:
The patent changes the measurement parameter from far-field to near-field conditions. By performing measurements in the near-field region where electromagnetic field characteristics differ, the system achieves accurate beamforming capability assessment without requiring large spatial distances, thus resolving the contradiction between measurement precision and spatial requirements
Solution Approach 2:
The patent uses an equivalent source model that mathematically represents the RIS structure. This equivalent source copying approach allows the measurement system to characterize RIS beamforming capabilities through near-field measurements and equivalent source reconstruction, eliminating the need for large far-field measurement spaces while maintaining measurement accuracy
2Area of stationary object
If a compact antenna test range with reflector is used, then spatial requirements are reduced, but additional equipment such as reflectors is required
Solution Approach 1:
The patent extracts and removes the reflector component from the measurement system. By eliminating the reflector and performing direct near-field measurements between the antenna and RIS, the system achieves compact spatial requirements without the complexity of additional equipment, resolving the contradiction between reduced area and device complexity
Solution Approach 2:
The patent enables the measurement system to perform self-characterization through near-field scanning and equivalent source reconstruction. The system uses the antenna itself to both illuminate and measure the RIS without requiring external reflectors or additional measurement equipment, achieving simplicity while maintaining compact dimensions
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 allows for efficient and cost-effective testing of RIS by minimizing spatial needs and enhancing dynamic range, particularly at high frequencies, while reducing the influence of stray signals and enabling accurate determination of reflection patterns.
Implementation Method 1
transmit the stimulus RF signal to the passive RF structure in a first polarization and/or in a second polarization
Implementation Method 2
configured to reflect impinging electromagnetic waves in a certain defined manner
Implementation Method 3
receive the reflected signal from the passive RF structure in the first polarization and/or in the second polarization
Data Source
AI summary
A system includes a positioner unit configured to hold a passive RF structure in an adaptable position. The system also includes an instrument configured to generate a stimulus RF signal and an RF antenna being connected to the instrument. The RF antenna is configured to transmit the stimulus RF signal to the passive RF structure in a first polarization and/or in a second polarization and to receive a reflected signal from the passive RF structure in the first polarization and/or in the second polarization. The instrument further is configured to obtain measurement data based on the stimulus RF signal and the reflected signal. An analysis circuit determines a corrected equivalent source of the passive RF structure based on a distance between the RF antenna and the passive RF structure and based on the measurement data, wherein the corrected equivalent source is corrected for an influence of the RF antenna.