3D OTA Antenna Array for RF Channel Emulation
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Solution Overview
Problem
Current over-the-air (OTA) testing methods for multiple antenna devices require a large number of transmit elements to accurately emulate real-world radio frequency (RF) signals, which is costly and degrades the test chamber's characteristics due to additional reflections, and existing technologies struggle to efficiently model and generate test signals for diverse radio systems like WCDMA and OFDMA.
Innovation Solution
A method involving an antenna array with at least one center antenna and multiple perimeter antennas, forming a cone of RF signal angles of arrival that subtends a range of 20° to 90°, allowing for coordinated RF signal transmission to a device-under-test within an anechoic chamber, with adjustable azimuth and elevation angles to simulate real-world conditions effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of transmit elements (probes) are used to accurately emulate real-world RF signals, then the accuracy of channel emulation is improved, but the cost increases and the test chamber characteristics are degraded due to additional reflections
Solution Approach 1:
The patent transitions from a two-dimensional planar probe arrangement to a three-dimensional spherical probe configuration. By positioning probes at multiple distances from the DUT (near field and far field regions) and distributing them spherically, the system achieves accurate channel emulation with fewer probes. This dimensional change allows the probe array to capture spatial signal characteristics more efficiently, resolving the contradiction between accuracy and complexity.
Solution Approach 2:
The patent divides the probe array into multiple groups positioned at different spherical distances from the DUT. Each group operates in different field regions (near field, far field), allowing segmented measurement of channel characteristics. This segmentation enables accurate channel emulation by capturing both near-field and far-field propagation effects without requiring a uniformly dense probe distribution, thus reducing the total number of probes needed.
2Area of stationary object
If a large number of probes are deployed in the test chamber, then the RF signal coverage is improved, but the test chamber characteristics are degraded due to additional reflections
Solution Approach 1:
By arranging probes spherically in three dimensions rather than in a two-dimensional plane, the system achieves comprehensive RF coverage with fewer probes. The spherical geometry naturally provides omnidirectional coverage while minimizing the total probe count, thereby reducing harmful reflections in the chamber.
Solution Approach 2:
The patent uses a limited number of probes to create virtual representations of multiple transmit antennas through signal processing. By measuring channel responses from the probe array and computing correlation matrices, the system synthesizes virtual MIMO channel characteristics without requiring physical copies of multiple transmit elements, thus avoiding the reflection problems associated with deploying many probes.
Data Source
AI summary
A method of emulating real world conditions of a radio frequency (RF) signal reaching a device-under-test (DUT) includes exposing the DUT to a cone of RF signal angles of arrival transmitting coordinated RF signals from an antenna array. The antenna array has at least one antenna located at a center of the antenna array and at least three antennas located at substantially equal distance from the center and from each other. Such configuration of the antennas in the antenna array defines a base of the cone to have a range of angles of 20° to 70°. The cone of RF signal angles of arrival and the DUT may be enclosed in a chamber such as an anechoic chamber. The method sets an azimuth angle and/or an elevation angle of the DUT with respect to the transmitted RF signals.