PCB Resonator Shell via Inverted Recess for Radar Level Measurement

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Solution Overview

Problem

Current microwave and radar-based level measurement devices face challenges in achieving low electrical losses and mechanical stability due to the need for a resonator at the waveguide transition, which often requires a cup-shaped resonator integrated into the printed circuit board, leading to contamination and compromised electrical and mechanical properties.

Innovation Solution

A printed circuit board with a non-conductive planar substrate and a micro-strip microwave guide is designed, featuring an annular connection region for the waveguide, a recess on the rear side forming a resonator shell, and plated-through holes for electrical connection, allowing for efficient microwave signal transmission and reception without separate insulation recesses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a cup-shaped resonator is integrated into the printed circuit board at the waveguide transition, then electrical losses are reduced and signal coupling is improved, but the mechanical stability deteriorates and contamination risk increases

Engineering Contradiction:

Improveelectrical lossesVSAvoidmechanical stability

Core Design Contradiction:

Loss of energyVSStability of the object's composition

Solution Approach 1:

Instead of creating a recess (removing material) to form the resonator cavity, the patent builds up the resonator by adding material - specifically by bonding a metal plate to the rear side of the printed circuit board in the region corresponding to the desired resonator volume. This inverted approach (adding vs. removing material) fundamentally resolves the mechanical stability issue while maintaining the electromagnetic resonator function.

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of operation

If a recess is introduced in the printed circuit board substrate to accommodate the resonator, then the resonator can be spatially arranged at the waveguide end, but contamination occurs and electrical properties are compromised

Engineering Contradiction:

Improvespatial arrangement of resonatorVSAvoidcontamination

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the conventional approach by not creating a recess (negative space) but instead building up the resonator structure by bonding a metal plate to the rear side of the PCB. This eliminates the open recess that would be susceptible to contamination while maintaining the resonator's spatial position at the waveguide end and its electromagnetic functionality.

Inventive Principle:

Principle #13The other way round (Inversion)

3Object-affected harmful factors

If a cover is used to close the recess, then contamination is avoided, but the electrical and electromagnetic properties deteriorate

Engineering Contradiction:

Improvecontamination protectionVSAvoidelectrical and electromagnetic properties

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

Rather than closing a recess with a cover (which interferes with electrical properties), the patent eliminates the recess entirely by building up the resonator structure with a bonded metal plate. This inverted approach simultaneously achieves contamination protection (no open recess) and maintains electrical/em electromagnetic properties (no cover interference).

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The resonator is formed as a composite structure combining the printed circuit board substrate with a bonded metal plate. This composite construction integrates the mechanical support function of the PCB with the electromagnetic resonator function of the metal plate, eliminating the need for separate covers or recesses.

Inventive Principle:

Principle #40Composite materials

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 enhances mechanical stability, electromagnetic reliability, and accuracy by integrating the resonator as a negative shape on the printed circuit board, reducing losses and simplifying the structure while maintaining high-quality signal transmission and reception.

Implementation Method 1

a microwave guide (16) for coupling a microwave signal into a waveguide (14) and vice versa

Methodology Applied

Scientific EffectElectromagnetic wave propagation: Electromagnetic Induction

Implementation Method 2

a resonator shell in which a bottom side of the waveguide is formed as a mirror image of a front side of the printed circuit board substrate

Methodology Applied

Scientific EffectElectromagnetic resonance: Resonance

Data Source

PatentUS10616996B2Printed circuit board for a radar level measurement device with waveguide coupling

Publication Date: 2020.04.07 VEGA GRIESHABER GMBH & CO

AI summary

A printed circuit board for a radar level measurement device with a printed circuit board substrate is provided, wherein a microwave signal is coupled via a microwave conductor into a waveguide. A connection region on a front side of the printed circuit board substrate serves to receive the waveguide. A shape of a resonator shell is generated inversely by producing an annular peripheral recess whose wall has an electromagnetically reflecting coating on a rear side of the printed circuit board substrate. The annular peripheral recess on the rear side, together with a region surrounded by the recess, forms a resonator for the injected microwave signals.