Dual-Reflector OTA Feed Layout for Stable Wideband Quiet Zones
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Solution Overview
Problem
Current over-the-air (OTA) measurement systems for testing devices under test require multiple feed antennas and positioners to cover wide frequency ranges, leading to increased costs and potential shifts in the quiet zone, which affects testing accuracy.
Innovation Solution
An OTA measurement system utilizing a reflector array with a main reflector and a sub-reflector, where multiple feed antennas are positioned such that the second feed antennas are offset from the focal point of the sub-reflector, allowing for reduced off-orthogonal angles and maintaining the quiet zone's center position, thereby eliminating the need for additional positioners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple feed antennas are mounted to a positioner to move each feed antenna into the phase center, then the frequency range coverage is improved, but the system costs increase due to the necessary positioner
Solution Approach 1:
The system divides the feed antenna array into multiple independent feed antennas that can be individually positioned at different locations relative to the reflector. This segmentation allows each antenna to cover specific frequency bands without requiring a complex positioner system, as the antennas are strategically placed to collectively cover the entire frequency range.
Solution Approach 2:
The reflector is designed to serve multiple functions: it reflects signals from feed antennas located at different positions (including offset positions) to create overlapping quiet zones that collectively cover a wide frequency range. This multi-functionality eliminates the need for a positioner while maintaining broad adaptability.
2Adaptability or versatility
If offset feed antennas are used to cover wide frequency range, then the frequency range coverage is improved, but the quiet zone shifts away from the center requiring a positioner for the device under test
Solution Approach 1:
The system transitions from a single-dimensional approach (one feed antenna at the phase center) to a multi-dimensional arrangement by positioning multiple feed antennas at different lateral offsets from the reflector's focal point. This spatial distribution in multiple dimensions allows the creation of multiple quiet zones that overlap to form a stable, centered composite quiet zone across wide frequency ranges.
Solution Approach 2:
Multiple quiet zones generated by offset feed antennas are merged through spatial overlap to create a composite quiet zone that remains centered. The combination of signals from multiple offset antennas produces a stable measurement region that does not shift with frequency changes, eliminating the need for device repositioning.
3Measurement precision
If a positioner is added to re-position the device under test, then the quiet zone position stability is improved, but the system costs increase
Solution Approach 1:
The system achieves quiet zone stabilization through the self-organizing properties of electromagnetic wave interference. Multiple offset feed antennas automatically create overlapping fields that form a stable, centered quiet zone without requiring active control or repositioning mechanisms. The system self-regulates the quiet zone position through the physical principles of wave propagation and interference.
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 configuration enables wideband testing across various frequency ranges without shifting the quiet zone, reducing costs and ensuring accurate far-field conditions for device testing, as the offset feed antenna arrangement effectively covers the entire frequency range with minimal impact on the quiet zone's center.
Implementation Method 1
at least one reflector is used that is located in a beam path established between the test location and a respective antenna in order to increase the traveling distance of the electromagnetic waves
Implementation Method 2
The plurality of feed antennas comprises a first feed antenna and at least one second feed antenna. The first feed antenna is located at the focal point of the sub-reflector. The at least one second feed antenna is located offset from the focal point of the sub-reflector.
Data Source
Figure 1~2
Figure 3~4
AI summary
An over-the-air (OTA) measurement system for testing a device under test (12), with a plurality of feed antennas (24, 26), a test location (16) for the device under test (12), and a reflector array (28) with a main reflector (30) and a sub-reflector (32). The plurality of feed antennas (24 ,26) face the sub-reflector (32). The reflector array (28) is located such that a signal path (24) is established between the plurality of feed antennas (24, 26) and the test location (16) via the sub-reflector (32) and the main reflector (30). The sub-reflector (32) has at least one focal point (36). The plurality of feed antennas (24, 26) comprise a first feed antenna (24) and at least one second feed antenna (26). The first feed antenna (24) is associated with the focal point (36) of the sub-reflector (32). The at least one second feed antenna (26) is located offset from the focal point (36) of the sub-reflector (32). Further, a method of testing a device under test (12) over-the-air is described.