Antenna Base for Signal Transmission Through Metallic Housing

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Solution Overview

Problem

RFID and NFC transponders face challenges in transmitting signals through metallic housings due to the conductive nature of these materials, which are impermeable to electromagnetic waves, leading to signal loss and inefficiency.

Innovation Solution

A device that couples electromagnetic waves from a primary antenna to secondary antennas inside and outside the housing using guided waves, with a dielectric filler to reduce losses and a common antenna base for minimal field interference, allowing for low-loss transmission and broadband capability by optimizing antenna lengths and shapes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a metallic housing is used for field devices, then mechanical strength and sealing are improved, but electromagnetic wave transmission is blocked causing signal loss

Engineering Contradiction:
Improvemechanical strengthVSAvoidsignal loss
Core Design Contradiction:
StrengthVSLoss of energy

Solution Approach 1:

The housing is segmented by creating a localized opening or aperture in the metallic housing, allowing electromagnetic waves to pass through while maintaining the overall structural integrity and sealing of the housing. The antenna system is divided into multiple components (primary antenna inside, secondary antenna outside) connected through the housing wall.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A dielectric material is introduced as an intermediary substance filling the housing opening, providing a transition medium that allows electromagnetic wave coupling between the interior and exterior environments while maintaining the housing's protective function.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If antennas are installed inside and outside the housing, then signal transmission through the housing is improved, but device complexity increases

Engineering Contradiction:
Improvesignal transmissionVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The antenna base serves multiple functions: it provides mechanical support for both the primary and secondary antennas, acts as a reference plane for electromagnetic field distribution, and serves as a mounting structure that integrates with the housing opening. The dielectric material simultaneously provides electrical insulation and mechanical filling.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The primary antenna inside the housing and the secondary antenna outside the housing are merged into a single functional system through the housing wall opening, creating a transmission path that couples the two environments without requiring separate independent systems.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If the housing opening is sealed with dielectric material, then airtightness is maintained, but antenna positioning requires additional holding devices

Engineering Contradiction:
ImproveairtightnessVSAvoidholding devices
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The dielectric filling material serves itself by providing both the sealing function and the mechanical support function. The material's physical presence in the housing opening automatically positions the antennas through its dielectric properties and physical constraints, eliminating the need for separate holding devices.

Inventive Principle:
Principle #25Self-service

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

Enables efficient and broadband transmission of RFID or NFC signals through metallic housings with reduced signal loss, maintaining the housing's seal and allowing for retrofitting without additional holding means, suitable for various frequency bands.

Implementation Method 1

The dielectric filling material shields the electromagnetic waves emitted by the first or second secondary antenna, thereby reducing losses

Methodology Applied
Scientific EffectDielectric shielding: Dielectric

Implementation Method 2

The transmission from the inside of the housing to the outside of the housing is effected by means of guided waves, the losses of which are lower than those of free waves

Methodology Applied
Scientific EffectGuided wave transmission: Waveguide

Data Source

PatentEP3231035B1Device for transferring signals from a metal housing
Publication Date: 2021.08.11 ENDRESS & HAUSER GMBH & CO KG
  • EP3231035B1 patent drawingFigure 1~2
  • EP3231035B1 patent drawingFigure 3
  • EP3231035B1 patent drawingFigure 4~5

AI summary

The invention relates to a device for transferring signals from at least one housing opening (2) of a housing (3), which is metallic at least in part, by means of electromagnetic waves (4) of at least one specific wavelength, comprising a transmitting/receiving unit (5) arranged in the housing (3) for generating and receiving the electromagnetic waves (4), at least one primary antenna (6) arranged in the housing (3) for decoupling the generated electromagnetic waves (4) of the transmitting/receiving unit (5) and for coupling and transferring received electromagnetic waves (4) to the transmitting/receiving unit (5), a first secondary antenna (7) for receiving the electromagnetic waves decoupled from the primary antenna (6), wherein the first secondary antenna is arranged within the housing (3) on the housing opening (2), a second secondary antenna (8) for receiving the electromagnetic waves (4) transferred from outside the housing (3), wherein the second secondary antenna (8) is arranged outside the housing (3) on the housing opening (2), wherein a reflection point (9) is arranged between the first and second secondary antennas (7, 8), such that an impedance jump occurs between the first and second secondary antennas (7, 8).