Polarizer-Assisted Star Isolation for RF Self-Interference
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Solution Overview
Problem
Current RF systems with high power transmitters and high sensitivity receivers face challenges in reducing Simultaneous Transmit and Receive (STAR) self-interference, often requiring a trade-off between transmission power and receiver sensitivity due to limitations in existing self-interference cancellation methods, particularly when antenna elements are at a fixed distance and have a set beam shape.
Innovation Solution
The implementation of a STAR system that uses signal polarizers to maintain far-field polarization efficiency for both transmission and reception while introducing a near-field polarization mismatch between the transmitter and receiver subsystems, reducing self-interference by converting the polarization of signals to orthogonal orientations, thereby minimizing coupling between the transmitter and receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the transmitter power is increased to maintain or increase operational range, then transmission effectiveness is improved, but receiver sensitivity is reduced due to self-interference
Solution Approach 1:
The patent segments the electromagnetic field interaction into two distinct polarization domains: the near-field region between transmitter and receiver uses orthogonal polarization to minimize coupling, while the far-field region maintains co-polarization for effective target interaction. This spatial segmentation of polarization strategies allows simultaneous high power transmission and high sensitivity reception.
Solution Approach 2:
The patent applies different polarization qualities to different spatial regions: orthogonal polarization is applied locally in the near-field region to reduce self-interference, while co-polarization is maintained in the far-field region for optimal target link performance. This local differentiation resolves the contradiction between transmission power and receiver sensitivity.
2Reliability
If cross-polarization isolation is used to reduce self-interference, then receiver sensitivity is improved, but far-field target link performance deteriorates due to polarization mismatch
Solution Approach 1:
The patent divides the electromagnetic propagation path into near-field and far-field segments, applying orthogonal polarization only to the near-field transmitter-receiver link while maintaining co-polarization for the far-field target interaction. This segmentation preserves both receiver sensitivity and target link effectiveness.
Solution Approach 2:
Different polarization qualities are applied to different parts of the signal path: orthogonal polarization locally at the receiver input to suppress self-interference, and co-polarization in the far-field for optimal target coupling. This resolves the contradiction between sensitivity and target link performance.
3Object-affected harmful factors
If physical barriers such as absorbers or reflective barriers are placed between transmitter and receiver, then self-interference is reduced, but system complexity and volume requirements increase
Solution Approach 1:
The patent replaces mechanical/physical barrier solutions (absorbers, reflective barriers, metasurfaces) with an electromagnetic field-based solution using polarization control. This substitution eliminates the need for bulky physical structures while achieving the same self-interference reduction goal, thereby reducing system complexity and volume requirements.
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 approach allows for higher transmission power without overwhelming the receiver, maintaining high sensitivity and reducing self-interference, thus enhancing the operational range and effectiveness of the system while preventing signal saturation.
Implementation Method 1
at least one polarizer between the remote target and the receiver subsystem operable to convert the polarization of the second signal to have a polarization that is orthogonal to the first signal and substantially the same as the polarization of the receiver subsystem
Data Source
AI summary
A Simultaneous Transmit and Receive (STaR) system utilizing high power transmitters and high sensitivity receivers in conjunction with one or more signal polarizers to maintain far-field polarization efficiency for both transmission and reception of same (or similar) frequency content at the same time. This STaR system maintains far-field polarization efficiency to remote target(s) while simultaneously introducing a near-field polarization mismatch between the transmission and receiver subsystems for higher isolation and reduced coupling.