Microwave Motion Sensor Reflector for Downward Detection
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Solution Overview
Problem
Existing microwave motion sensors with reflectors enhance detection underneath the sensor by reflecting part of the main beam, which can be detrimental to the protected region by altering the radiation pattern.
Innovation Solution
A microwave motion sensor with an array of radiating elements and a reflector positioned above the antenna to shape the radiation pattern, allowing the main beam to remain unaffected while enhancing detection by reflecting side lobe energy downward.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reflector is used to reflect part of the main beam downward to enhance detection underneath the sensor, then detection capability beneath the sensor is improved, but the radiation pattern in the protected region is altered and detection performance deteriorates
Solution Approach 1:
The reflector is designed with specific geometric parameters (width, height, curvature radius) to create different radiation characteristics in different spatial regions. The reflector shape is optimized to direct side lobe energy downward while leaving the main beam intact for protected region coverage, achieving local optimization of detection capability without compromising overall system performance
Solution Approach 2:
The patent optimizes specific parameters of the reflector including its width (0.5λ to 2λ), height (0.3λ to 1λ), and curvature radius (0.2λ to 0.5λ) to control the radiation pattern. By adjusting these parameters, the system achieves enhanced downward detection through side lobe reflection while maintaining the main beam characteristics for protected region monitoring
2Area of stationary object
If a reflector is added to enhance downward detection, then detection coverage underneath the sensor is improved, but device complexity increases
Solution Approach 1:
The reflector employs a curved surface (cylindrical or spherical curvature) rather than a flat surface to achieve better radiation pattern control. The curvature allows the reflector to shape the side lobe energy more effectively and creates a more compact structure that integrates well with the antenna element, reducing overall device complexity while enhancing downward detection coverage
3Power
If the reflector reflects main beam energy downward, then signal strength underneath the sensor is improved, but energy distribution in the protected region becomes unbalanced
Solution Approach 1:
The radiation energy is segmented into different functional components: the main beam maintains its original direction for protected region coverage, while only the side lobe energy is redirected downward by the reflector. This segmentation allows the system to enhance downward detection without compromising the energy distribution balance in the protected region
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 enhanced detection beneath the sensor without affecting the main beam, improving coverage and meeting requirements like the 2006/2007 draft EN50131-2-4 G3 crawl test by ensuring detection of objects below the sensor.
Implementation Method 1
A reflector is disposed above the antenna for downward shaping the radiating signal, where the antenna(s) with the reflector provide a radiation pattern in which a main beam is transmitted in a direction orthogonal to a surface of said antenna(s) and a side lobe transmitted downward below the microwave motion sensor
Implementation Method 2
A MW motion sensor transmits a microwave signal toward a region to be monitored and in the event that movement is detected within the region, the microwave signal is reflected back (echo) from such movement and is modulated due to the Doppler Effect
Data Source
AI summary
A microwave motion sensor including a patch antenna having a plurality of microwave radiating elements for transmitting and receiving a microwave signal where each microwave radiating element is of the antenna in an array configuration. A reflector is disposed above the antenna for downward shaping the radiating signal, where the microwave radiating elements together with the reflector provide a radiation pattern where a main beam is transmitted in a direction orthogonal to a surface of said antenna and a sided lobe transmitted downward in amplitude below the microwave motion sensor.