Same-Aperture STAR System T/R Isolation via Signal Subtraction
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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 simultaneous transmit and receive (STAR) systems, particularly due to the narrow bandwidth of ferrite circulators and the physical constraints of impedance matching, which restricts the ability to simultaneously transmit and receive signals in the same frequency band.
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, including photonic and electronic differencing devices, to enhance T/R isolation and enable STAR operations across a broader frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferrite circulators are used to achieve T/R isolation, then transmit-to-receive isolation is improved, but bandwidth is limited due to the narrow bandwidth of ferrite circulators
Solution Approach 1:
The patent divides the T/R isolation function into multiple independent paths: (1) a ferrite circulator providing initial isolation, (2) an impedance matching network addressing reflections, and (3) a signal subtractor combining outputs from multiple paths. This segmentation allows each component to operate within its optimal bandwidth range while the combined system achieves wideband performance.
Solution Approach 2:
The patent merges multiple signal paths with different isolation characteristics into a single combined output through the signal subtractor. By combining the ferrite circulator path, impedance matching path, and their complementary outputs, the system achieves T/R isolation across a wide bandwidth that exceeds the capability of any single component.
2Productivity
If impedance matching techniques are applied, then signal transmission efficiency is improved, but T/R isolation is restricted due to physical constraints of impedance matching
Solution Approach 1:
The patent introduces an impedance matching network as an intermediary component between the antenna and the signal processing paths. This network optimizes signal transmission efficiency by matching impedances while its output is fed to the signal subtractor, which then restores T/R isolation by subtracting the matched signal from the total received signal.
3Reliability
If multiple antenna elements are arranged with receive antenna in null of transmit antenna pattern, then T/R isolation is achieved, but bandwidth is limited
Solution Approach 1:
The patent employs dynamic signal processing through the signal subtractor that actively combines and processes signals from multiple paths in real-time. This dynamic approach allows the system to maintain T/R isolation across varying frequencies by adaptively processing signals, unlike static spatial nulling methods that are frequency-dependent.
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.