True Time Delay Beamforming with Make-Before-Break Switching
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Solution Overview
Problem
True time delay (TTD) beam formers using RF MEMS switches face challenges with hot switching, which leads to increased risk of switch failure due to micro arcing, while cold switching requires shutting down the RF input, causing circuit complexity and degradation of the antenna beam pattern.
Innovation Solution
Implementing a make-before-break switching technique and sparse matrix control strategy to activate parallel signal transmission paths within TTD modules, allowing beam steering without shutting down the input signal and minimizing micro arcing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hot switching is used to keep TTD module continuously operational, then productivity is improved, but reliability deteriorates due to micro arcing at switch contacts
Solution Approach 1:
The patent applies preliminary action by closing the second switch before opening the first switch during the switching sequence. This ensures that the RF signal path is established through the second switch before the first switch opens, preventing interruption of the RF signal and avoiding micro arcing at the first switch contacts. The make-before-break switching sequence is implemented by controlling the switches in a specific order where the incoming switch is closed before the outgoing switch is opened.
2Reliability
If cold switching is used to protect RF MEMS switches from micro arcing, then reliability is improved, but device complexity increases due to need to shut down RF input
Solution Approach 1:
The patent implements continuity of useful action by maintaining the RF signal continuously flowing through the TTD module during switching operations. The make-before-break switching sequence ensures that there is always an active RF signal path from input to output, eliminating the need to shut down the RF input signal during switching. This keeps the TTD module continuously operational while protecting the switches from micro arcing damage.
3Reliability
If RF input is shut down for cold switching, then reliability is improved, but productivity deteriorates due to signal interruption
Solution Approach 1:
The patent uses an intermediary approach by introducing a parallel switching path with a second switch that provides an alternative RF signal route. When switching between delay lines, the RF signal is redirected through the second switch before the first switch opens, maintaining continuous signal flow. The second switch acts as an intermediary path that allows seamless transition without interrupting the RF signal to the antenna element.
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 enhances the reliability and lifetime of switching elements by preventing micro arcing and maintaining an ITU-compatible radiation pattern during beam steering, enabling continuous operation without degrading the TTD modules or distorting the beam.
Implementation Method 1
These RF MEMS switches use an electrically actuated mechanical movement to achieve an open circuit or a closed circuit in a RF transmission line
Implementation Method 2
Hot switching occurs when an RF MEMS switch is actuated from the off position to the on position while a large voltage potential exists across the terminals of the RF MEMS switch or when an RF MEMS switch is de-actuated from the on position to the off position while a large current is flowing through the closed contacts of the RF MEMS switch. In either instance of hot switching, micro arcing occurs at the RF MEMS switch contacts, which exacerbates the degradation of the material
Data Source
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AI summary
An antenna system includes a plurality of true time delay (TTD) modules, each having a plurality of switching elements configured to selectively define alternative RF signal transmission paths between a signal input and a signal output of the TTD module. A controller is programmed to control the plurality of TTD modules to steer a beam according to a make-bef ore-break switching technique by closing a first pair of switching elements within at least a subset of the plurality of TTD modules to activate a first RF signal transmission path; closing a second pair of switching elements of the subset of the plurality of TTD modules to activate a second RF signal transmission path in parallel with the first RF transmission path; and opening the first pair of switching elements of the subset of TTD modules after closing the second pair of switching elements.