Coaxial Probe Fluid Level Sensor Using Microwave Pulse Analysis
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Solution Overview
Problem
Existing methods for detecting fluid levels and contaminants in containers, particularly in aviation fuel tanks, are inaccurate, unreliable, and fail to meet electromagnetic interference (EMI) and electrostatic discharge (ESD) safety requirements, and do not effectively monitor the presence and amount of contaminants like water.
Innovation Solution
A coaxial probe system using Micropower Impulse Radar (MIR) technology with a digital signal processor (DSP) to provide time domain reflectometric readings, allowing for accurate level measurement and contaminant detection by analyzing the propagation speed of microwave pulses through the fluid, while being hermetically sealed and low-voltage operated to meet aircraft safety standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional radar technology is used to detect fluid levels, then measurement capability is provided, but electromagnetic interference sensitivity and failure to meet EMI/ESD safety requirements occur
Solution Approach 1:
The patent replaces traditional radar electromagnetic sensing with a time-domain reflectometry system using a coaxial probe that transmits microwave pulses through the fluid medium. This substitution of the sensing mechanism achieves fluid level measurement while significantly reducing electromagnetic interference sensitivity and meeting aviation EMI/ESD safety requirements.
Solution Approach 2:
The patent introduces a coaxial probe as an intermediary element that physically contacts the fluid to transmit microwave pulses. This intermediary approach allows measurement of fluid level and dielectric properties through direct contact, eliminating the need for traditional electromagnetic radar waves that cause interference issues.
2Measurement precision
If conventional level sensing methods are used, then basic level detection is achieved, but accurate contaminant detection and fluid characterization are not provided
Solution Approach 1:
The patent makes the coaxial probe system multi-functional by enabling it to perform multiple measurements: fluid level detection, dielectric constant measurement, and contaminant identification. The same hardware platform provides comprehensive fluid characterization without requiring separate specialized devices for each function.
Solution Approach 2:
The patent measures changes in the dielectric constant of the fluid by analyzing the reflection coefficient of transmitted microwave pulses. This parameter change approach enables differentiation between clean fuel and contaminated fuel, as well as determination of fluid level, using variations in electromagnetic wave propagation characteristics.
3Reliability
If high-power radar systems are used for fluid measurement, then measurement range is extended, but electromagnetic interference and noise generation increase
Solution Approach 1:
The patent uses periodic transmission of low-power microwave pulses through the coaxial probe into the fluid. This periodic pulsed action allows accumulation of signal data over multiple cycles, improving measurement reliability in noisy environments while maintaining low average power output that minimizes electromagnetic noise generation.
Solution Approach 2:
The patent employs feedback processing of the reflected microwave pulse signals to enhance measurement reliability. By analyzing the reflection coefficient and comparing it against known dielectric constant values, the system can reliably identify fluid type and level even in the presence of environmental noise, without requiring high transmission power.
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 system achieves precise fluid level measurement and contaminant detection, even in noisy environments, with improved signal clarity and reduced noise interference, ensuring safe and reliable operation while meeting EMI and ESD requirements.
Implementation Method 1
circuitry designed to provide time domain reflectometric readings to determine the level of, and presence of, impurities in a liquid
Implementation Method 2
sending a very low microwave pulse along a waveguide, a probe
Implementation Method 3
At least part of the pulse is reflected at the fluid being measured
Implementation Method 4
The propagation speed of the microwave pulse through a material can be used to ascertain the identity of the material through which the pulse is traveling. The propagation speed is directly related to the material's dielectric constant
Data Source
AI summary
A liquid characterization and level sensor with a coaxial probe attached to a closed loop servo circuitry combined with a DSP and novel algorithms to scan, lock and track signals to ascertain the level and purity of fluid in a container.