Microwave Planar Sensor PCB Cavity Packaging
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Solution Overview
Problem
Existing microwave planar sensors face challenges with high manufacturing costs, laborious assembly processes, inconsistent geometrical structures, and inadequate electromagnetic shielding, which affect their reliability and efficiency in detecting moving targets.
Innovation Solution
A microwave planar sensor design featuring a three-layered microwave board with an oscillator/mixer layer, antenna layer, and ground layer, bonded together, and a support board with a continuous cavity for improved mechanical and electrical integration, along with an adjustable baseboard for tuning the detecting angle and frequency, eliminating the need for conductive adhesives and enhancing electromagnetic shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If metal casting process is used for packaging microwave circuits, then electromagnetic shielding is provided, but manufacturing cost increases and assembly complexity increases
Solution Approach 1:
The patent replaces the metal casting process with a PCB-based packaging structure that uses circuit board layers and soldering techniques instead of traditional metal enclosures. The PCB ground layers and metallic vias provide electromagnetic shielding through conductive pathways integrated into the board structure, eliminating the need for separate metal casting and conductive adhesive application processes.
Solution Approach 2:
The patent combines the electromagnetic shielding function with the structural support function by integrating ground layers and shielding elements directly into the PCB packaging structure. The ground layers serve dual purposes as both structural components and electromagnetic shields, reducing the need for separate shielding components and simplifying manufacturing.
2Object-affected harmful factors
If metal casting process is used for packaging microwave circuits, then electromagnetic shielding is provided, but assembly time increases due to curing time for conductive adhesives
Solution Approach 1:
The patent replaces conductive adhesive bonding with standard PCB soldering techniques. The metallic vias and ground layers are electrically connected through solder joints during normal PCB assembly processes, eliminating the need for adhesive application and curing time. This allows for faster assembly using conventional automated soldering equipment.
3Ease of manufacture
If metal stamping process is used for packaging, then manufacturing cost is reduced, but geometrical consistency and precision deteriorate
Solution Approach 1:
The patent replaces metal stamping with PCB fabrication processes. The PCB packaging structure is manufactured using standard circuit board manufacturing techniques including copper foil lamination, photolithography, and etching, which provide superior dimensional consistency and precision compared to metal stamping. The rigid PCB substrate maintains precise geometrical relationships between components without the variability inherent in stamped metal parts.
4Object-affected harmful factors
If conductive adhesives are used for connecting metal components, then electromagnetic shielding is achieved, but connection strength is insufficient
Solution Approach 1:
The patent replaces conductive adhesive bonding with solder joints for connecting metallic vias and ground layers to the PCB. Soldering provides both strong mechanical bonding and reliable electrical connection, eliminating the weak connection strength issue associated with conductive adhesives while maintaining electromagnetic shielding effectiveness through the continuous conductive pathways.
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
This design reduces manufacturing costs, improves connection reliability, maintains geometrical consistency, and provides effective electromagnetic shielding, allowing for efficient detection of moving targets with adjustable sensitivity and frequency tuning.
Implementation Method 1
an oscillator configured to generate at least one microwave signal
Implementation Method 2
a transmit antenna coupled to the oscillator for transmitting a microwave signal generated by the oscillator into the detection area
Implementation Method 3
a receive antenna coupled to the signal mixer for receiving a reflected signal reflected by the target
Implementation Method 4
the microwave signal is reflected back (echo) from such movement and is modulated due to the Doppler Effect. When a signal is reflected from a moving object, it is shifted in frequency. The shift in frequency is called the Doppler Effect
Data Source
AI summary
A microwave planar sensor for detecting the presence and movement of a target in a detection area, including a microwave board and a support board. The microwave board includes an oscillator/mixer layer, an antenna layer and a ground layer sandwiched between the oscillator/mixer layer and the antenna layer, when the oscillator/mixer layer and the antenna layer are bonded together. The oscillator/mixer layer includes an oscillator configured to generate at least one microwave signal and a signal mixer electrically coupled to the oscillator. The signal mixer is configured to combine a microwave signal generated by the oscillator and a reflected signal reflected by the target in the detection area, thereby generating an intermediate frequency signal having a Doppler frequency. The antenna layer includes a transmit antenna coupled to the oscillator for transmitting a microwave signal generated by the oscillator into the detection area and a receive antenna coupled to the signal mixer for receiving a reflected signal reflected by the target. The support board includes a top surface bonded to the microwave board through a first metal layer coated on the top surface. The support board further includes a continuous cavity extending from the top surface for accommodating the oscillator and the mixer of the oscillator/mixer layer, the surface of the cavity coated with a second metal layer.