True Time Delay Module With RF MEMS Switches
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Solution Overview
Problem
Existing electronically steerable array antenna systems face challenges in developing small, low-power, broadband antenna systems due to high power dissipation and interference between signal transmission lines, leading to poor beam steering performance and increased size and cost.
Innovation Solution
A true time delay (TTD) module with a substrate and transmission lines of varying lengths, incorporating high-speed RF MEMS switches and intermediate switching elements that divide delay lines into shorter segments, reducing electromagnetic coupling and insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional phase shifters and high power components are used for beam steering, then beam steering functionality is achieved, but power dissipation increases and system complexity increases
Solution Approach 1:
The patent replaces traditional electronic phase shifters and high-power components with a true time delay module using RF MEMS switches. This mechanical/electromechanical substitution eliminates the need for high-power dissipation components while maintaining beam steering functionality through precise time delay control of RF signals.
Solution Approach 2:
The invention changes the beam steering mechanism from phase shifting to true time delay control. By using multiple transmission lines with different lengths and selecting specific paths via RF MEMS switches, the system achieves beam steering through time delay parameter variation rather than phase shifting, resulting in lower power dissipation.
2Measurement precision
If multiple transmission lines are used to achieve desired delay, then time delay precision is improved, but electromagnetic coupling between lines increases causing interference
Solution Approach 1:
The patent segments the transmission path into multiple discrete transmission lines of different lengths, each controlled by individual RF MEMS switches. This segmentation allows precise time delay selection while the compact integration and switching architecture minimizes electromagnetic coupling between the segmented paths.
Solution Approach 2:
The RF MEMS switches act as intermediaries between the multiple transmission lines and the output. These switches selectively connect only the desired transmission line to the output at any given time, preventing electromagnetic coupling and interference between adjacent transmission lines while maintaining precise time delay control.
3Loss of time
If long electrical length transmission lines are used to achieve half wavelength resonances, then desired delay time is achieved, but signal transmission quality deteriorates due to suckout resonance
Solution Approach 1:
The patent uses dynamically controllable RF MEMS switches to select among multiple fixed-length transmission lines. This dynamic selection allows the system to achieve the desired delay time without being constrained by fixed long transmission lines that would cause half-wavelength resonances and signal degradation.
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
The solution effectively eliminates unwanted bandstop resonances, maintains good signal transmission across broadband frequency applications, and enables the fabrication of low-cost, small-scale, and lightweight ESA or PAA systems with reduced power dissipation.
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
The amount of time it takes for a signal to be transmitted between the electronics and the antenna is controlled by selecting a particular combination of transmission lines, which imparts a desired amount of phase or time delay on the RF signal
Implementation Method 3
TTD modules may experience interference between the individual signal transmission lines, which degrades the beam steering performance of the TTD module. Such interference is especially prevalent in TTD modules utilized in broadband frequency signal processing applications as a result of the large number of transmission lines utilized to achieve the desired delay
Data Source
AI summary
A true time delay (TTD) module includes a substrate and a transmission line formed on the substrate. The transmission line includes time delay lines that define signal paths of varying lengths between a signal input and a signal output of the TTD module. A plurality of switching elements are positioned along the transmission line and are selectively controllable to define a signal transmission path between the signal input and the signal output. The switching elements include an input switching element positioned at a first end of each of the plurality of time delay lines, an output switching element positioned at a second end of each of the plurality of time delay lines, and at least one intermediate switching element positioned between the input switching element and the output switching element of at least one of the plurality of time delay lines.