RFID Antenna Interference for Spatial Detection Control

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Solution Overview

Problem

Existing RFID systems face challenges in reliably and inexpensively limiting the transmission range, particularly in UHF systems, due to varying transponder sensitivities and the difficulty in controlling the detection area, which leads to inefficient and incomplete detection of transponders.

Innovation Solution

The method involves using an additional antenna that generates a signal that interferes with the transmission signal of the main antenna, reducing the sensitivity of transponders and spatially limiting the transmission range by ensuring the additional antenna's signal is either of the same or a different frequency, modulated, or inverted, thereby disrupting communication between the transponder and the main antenna.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the transmission range is extended to detect more transponders, then the detection coverage is improved, but unintentional detection of transponders outside the intended zone occurs

Engineering Contradiction:
Improvedetection coverageVSAvoidspatial precision
Core Design Contradiction:
Area of stationary objectVSMeasurement precision

Solution Approach 1:

The patent applies preliminary anti-action by using additional antennas to transmit interfering signals that preemptively prevent transponders outside the intended zone from being detected. The interfering signals are transmitted in advance to create a null zone or dead zone where transponders cannot respond, thus preventing unwanted detections before they occur.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The patent converts the harmful effect of signal interference into a beneficial spatial filtering mechanism. By intentionally introducing interfering signals from additional antennas, the system creates controlled zones where transponders are prevented from responding, thus converting signal interference from a nuisance into a useful tool for defining precise detection boundaries.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If the transmission power is increased to improve detection reliability, then the detection reliability is improved, but the energy consumption increases

Engineering Contradiction:
Improvedetection reliabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies periodic action by transmitting interfering signals only during specific time intervals when detection is required, rather than continuously. The additional antennas transmit interfering signals periodically or on-demand based on detection needs, reducing overall energy consumption while maintaining detection reliability when required.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent changes transmission parameters dynamically by adjusting the power and timing of interfering signals from additional antennas based on detection requirements. The system modifies transmission parameters such as signal strength, duration, and timing to achieve reliable detection only when necessary, thereby reducing overall energy consumption.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If multiple directional antennas are used to limit transmission range, then the spatial precision is improved, but the device complexity increases

Engineering Contradiction:
Improvespatial precisionVSAvoidantenna system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies multi-functionality by using additional antennas that serve dual purposes: they both extend detection coverage in certain directions and simultaneously create interfering signals to prevent detection in other directions. This single component performs multiple functions, reducing the need for separate directional antennas and simplifying the overall system.

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

Solution Approach 2:

The patent inverts the conventional approach by using additional antennas not primarily for extending coverage but for creating controlled interference zones. Instead of using multiple directional antennas to shape the beam, the system uses omnidirectional or broad-beam antennas combined with interfering signals to achieve spatial precision, effectively inverting the traditional method.

Inventive Principle:
Principle #13The other way round (Inversion)

4Productivity

If continuous transmission is used to maintain detection capability, then the detection availability is improved, but the energy consumption increases

Engineering Contradiction:
Improvedetection availabilityVSAvoidenergy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent applies periodic action by implementing intermittent transmission schedules where the additional antennas transmit interfering signals only during specific intervals when detection is required. The system alternates between transmission and idle periods, maintaining detection availability when needed while significantly reducing overall energy consumption compared to continuous transmission.

Inventive Principle:
Principle #19Periodic action

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 approach effectively limits the transmission range to specific areas, preventing unintentional detection of transponders outside the intended zone, while reducing energy consumption and avoiding the need for continuous transmission, thus enhancing the efficiency and precision of transponder detection.

Implementation Method 1

the at least one additional antenna transmits at least one additional signal at least temporarily during the reception process of the transmission signal by the transponder, and that the additional signal disturbs or reduces in intensity the transmission signal received by the at least one transponder

Methodology Applied
Scientific EffectElectromagnetic interference: Interference

Implementation Method 2

In the RF range, energy and data transmission are based on the magnetic coupling of the alternating fields of the reader and the transponder in close proximity

Methodology Applied
Scientific EffectMagnetic coupling: Electromagnetic Induction

Implementation Method 3

The antenna coil and the resonant capacitor form an electrical resonant circuit and are tuned to their operating frequency

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP3734494A1Method for detecting at least one transponder with a radio system, and radio system
Publication Date: 2020.11.04 FEIG ELECTRONIC GMBH
  • EP3734494A1 patent drawingFigure 1
  • EP3734494A1 patent drawingFigure 2
  • EP3734494A1 patent drawingFigure 3

AI summary

The invention relates to a method for detecting at least one transponder with a radio system comprising at least one reader, at least one transmit/receive antenna, and at least one transponder, wherein: - at least one additional antenna is provided, - the at least one additional antenna transmits at least one additional signal at least temporarily during the reception of the transmitted signal by the transponder, - the additional signal interferes with or reduces the intensity of the transmitted signal received by the at least one transponder from the at least one transmit/receive antenna, - the at least one transmit/receive antenna and the at least one additional antenna have spatially distinct transmission ranges. Furthermore, the invention relates to a radio system.