Single-Antenna Microwave Motion Detection With Impedance Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing motor vehicle detection systems face limitations in range and complexity, particularly with near-field radiofrequency antennas and far-field microwave systems that require multiple antennas, complex digital processing, and high power consumption, leading to inefficiencies and increased costs.
Innovation Solution
A device using a radiating impedance module with a detection antenna, MOSFET transistor, and impedance matcher forms a closed-loop electrical circuit that detects movement by analyzing impedance changes through a single antenna, utilizing analog components to simplify detection and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If far-field microwave detection is implemented using multiple antennas and digital processing, then detection range is improved (up to 30 meters), but device complexity and power consumption increase significantly
Solution Approach 1:
The patent combines transmitting and receiving functions into a single antenna system. The same antenna that transmits microwave pulses also receives reflected signals, eliminating the need for separate transmitting and receiving antennas. This merging reduces component count and system complexity while maintaining far-field detection capability up to 30 meters.
Solution Approach 2:
The single antenna serves multiple functions: it acts as both a transmitting antenna for sending microwave pulses and a receiving antenna for capturing reflected signals from moving targets. This multi-functionality reduces the number of components needed while achieving the desired detection range and performance.
2Length of stationary object
If far-field microwave detection with multiple antennas is used, then detection range is improved, but power consumption increases due to complex digital processing and multiple transmitting antennas
Solution Approach 1:
By merging transmitting and receiving functions into a single antenna, the system eliminates the power consumption associated with operating multiple high-power transmitting antennas. The single antenna alternates between transmission and reception modes, significantly reducing overall power requirements while maintaining detection range.
Solution Approach 2:
The system uses periodic pulsed transmission instead of continuous wave transmission. The single antenna transmits microwave pulses at intervals and listens for reflected signals during the off periods. This periodic operation reduces average power consumption compared to continuous transmission by multiple antennas, while still achieving far-field detection capability.
3Device complexity
If near-field radiofrequency antennas are used, then device complexity is reduced, but detection range is limited to less than 5 centimeters
Solution Approach 1:
The patent changes the operating parameters of the antenna system by using wideband microwave pulses instead of continuous near-field signals. By transmitting short microwave pulses and analyzing the time-of-flight and Doppler shift of reflected signals, the system achieves far-field detection capability while maintaining relative system simplicity. The single antenna operates in pulsed mode with controlled impedance matching to optimize both range and simplicity.
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 provides efficient, reliable, and cost-effective movement detection with reduced power consumption, enabling detection over a range of up to 10 meters and integration with existing communication modules, while adhering to radio approval thresholds.
Implementation Method 1
a detection antenna (112) configured to resonate at a predetermined fixed frequency to transmit microwaves and to receive microwaves reflected from the person
Implementation Method 2
a MOSFET transistor and an impedance matcher forming a closed-loop electrical circuit oscillating at the predetermined fixed frequency
Implementation Method 3
the impedance matcher being installed between the gate and the drain of the transistor and being configured to match the impedance of the detection antenna to the impedance of the transistor
Implementation Method 4
The impedance being stable when the frequency of the waves reflected from the person is equal to the frequency of the waves transmitted at the predetermined fixed frequency, indicating an absence of movement of the person, and different when the frequency of the waves reflected from the person differs by a frequency difference of greater than a threshold with respect to the predetermined fixed frequency, indicating the detection of a movement of the person
Data Source
AI summary
A device for detecting movement of a person by microwaves for a motor vehicle, the device including a radiating impedance module configured to be powered by a DC voltage supply and including a detection antenna, a MOSFET transistor and an impedance matcher forming a closed-loop electrical circuit oscillating at the predetermined fixed frequency when the circuit is powered by the voltage provided by the DC voltage supply.