Compact Passive Repeater for Wireless Sensing
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Solution Overview
Problem
Existing wireless sensing technologies face challenges in achieving a compact, passive device with low externally provided power requirements and sufficient wireless transmission range, particularly in applications like structural health monitoring where on-board energy may not be feasible.
Innovation Solution
The development of compact passive repeaters using harmonic repeaters with conjugate-matched three-dimensional antennas and diode-based frequency multipliers, which re-radiate return signals at twice the frequency of the interrogation signal, enabling efficient wireless transmission over long distances with minimal power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If passive wireless sensing devices are used to reduce power consumption, then energy requirements are reduced, but wireless transmission range is limited to short distances
Solution Approach 1:
The patent introduces an active repeater node as an intermediary between the passive sensing device and the remote monitoring system. The repeater receives weak signals from passive tags, amplifies them, and retransmits them at higher power, enabling long-range communication while keeping the passive device itself low-power consuming
Solution Approach 2:
The system is segmented into three functional components: passive sensing tags (ultra-low power), active repeater nodes (moderate power for signal boosting), and central monitoring systems. This segmentation allows each component to operate at appropriate power levels, with the repeater handling the power-intensive transmission function
2Length of stationary object
If on-board energy resources are used to sustain active sensing devices, then wireless transmission range is improved, but device complexity and size increase
Solution Approach 1:
The patent extracts the power-intensive functions (signal amplification, long-range transmission) from the sensing device itself and relocates them to separate repeater nodes. The sensing device retains only the simple passive tagging function, eliminating batteries and complex power management circuitry
3Ease of operation
If compact geometry is used for deployment ease, then ease of installation is improved, but antenna performance and transmission efficiency deteriorate
Solution Approach 1:
The patent employs three-dimensional printed antennas that utilize vertical and lateral spatial dimensions to achieve resonant lengths appropriate for RF operation. This allows compact form factors while maintaining the electrical length required for efficient radiation, solving the contradiction between physical size and antenna performance
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
These repeaters achieve a communication range of greater than 50 meters using a 2 W source in a free-space environment, providing effective wireless sensing capabilities with reduced power requirements and compact geometry, suitable for embedded monitoring applications.
Implementation Method 1
the repeater has a communication range of greater than approximately 50 m using a 2 W source in a free-space environment
Data Source
AI summary
In one embodiment, a repeater for wireless sensing includes a base substrate, a front substrate, a rear substrate, a receive antenna formed on the front substrate, a transmit antenna formed on the rear substrate, and a frequency multiplier formed on the base substrate between the antennas.