Same-Aperture STAR System T/R Isolation via Signal Differencing
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Solution Overview
Problem
Current technologies face limitations in achieving sufficient transmit-to-receive (T/R) isolation over a wide bandwidth for same-aperture any-frequency simultaneous transmit and receive (STAR) systems, primarily due to the narrow bandwidth of ferrite circulators and the physical constraints of antenna return loss improvement.
Innovation Solution
The implementation of a three-port signal connector with a signal isolator and a differencing device that subtracts the transmit signal from the receive path, combined with various impedance matching and signal processing techniques to enhance T/R isolation, including the use of photonic and electronic differencing devices and signal isolators, allows for improved isolation across a broader bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferrite circulators are used to achieve T/R isolation, then isolation performance is improved, but bandwidth is limited
Solution Approach 1:
The patent segments the isolation function into multiple components: ferrite circulator provides initial isolation, while additional isolators and a differencing device provide further isolation stages. This segmentation allows each component to operate within its optimal bandwidth range while the combined system achieves wide bandwidth coverage.
Solution Approach 2:
The patent combines multiple isolation mechanisms (ferrite circulator, isolators, and differencing device) into a unified T/R isolation system. The ferrite circulator and isolators work together in parallel, with the differencing device providing additional isolation, achieving both high isolation performance and wide bandwidth coverage.
2Reliability
If antenna return loss improvement is pursued, then T/R isolation is enhanced, but physical constraints limit the improvement
Solution Approach 1:
The patent introduces isolators as intermediary devices between the antenna and the receiver to protect the receiver from transmit signal interference. These isolators act as mediators that absorb or reflect unwanted signals, enhancing T/R isolation without requiring complex antenna redesign.
Solution Approach 2:
The patent replaces purely mechanical/physical antenna modifications with electronic signal processing approaches. The differencing device uses electronic subtraction of the transmit signal from the receive path, achieving isolation without physical constraints of antenna design.
3Reliability
If multiple antenna elements are arranged to place receive antenna in null of transmit pattern, then T/R isolation is achieved, but bandwidth is limited
Solution Approach 1:
The patent employs dynamic signal processing through the differencing device that adaptively subtracts the transmit signal from the receive path. This dynamic approach allows the system to maintain high T/R isolation across varying frequencies and conditions, unlike static spatial nulling approaches.
4Reliability
If signal processing is used to extend T/R isolation, then isolation performance is improved, but the bandwidth over which sufficient isolation can be achieved remains limited
Solution Approach 1:
The patent designs the differencing device to perform multiple functions: it subtracts the transmit signal, provides additional isolation, and operates across wide bandwidth. This universal device handles various signal conditions and frequency ranges, extending the effective bandwidth beyond what single-function devices can achieve.
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 enables T/R isolation exceeding 60 dB over a wide bandwidth, effectively reducing the transmit signal interference in the receive path, thereby enhancing the performance of same-aperture any-frequency STAR systems.
Implementation Method 1
A signal isolator is connected between the transmit signal path and the three-port signal connector. The isolator is configured to isolate a transmit signal from an antenna from a receive signal at the receive signal path.
Implementation Method 2
A differencing device is connected between the three-port signal connector and the receive signal path. The differencing device is configured to subtract a transmit signal from a receive signal at the receive signal path.
Data Source
AI summary
A same-aperture any-frequency simultaneously transmit and receive (STAR) system includes a signal connector having a first port electrically coupled to an antenna, a second port electrically coupled to a transmit signal path, and a third port electrically coupled to receive signal path. The signal connector passes a transmit signal in the transmit signal path to the antenna and a receive signal in the receive signal path. A signal isolator is positioned in the transmit signal path to remove a residual portion of the receive signal from transmit signal path. An output of the signal isolator provides a portion of the transmit signal with the residual portion of the receive signal removed. A signal differencing device having a first input electrically coupled to the output of the signal isolator and a second input electrically coupled to the third port of the signal connector subtracts a portion of the transmit signal in the receive signal path thereby providing a more accurate receive signal.