Dual-Antenna RFID Tag Finder with Null Pattern Direction

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Solution Overview

Problem

RFID readers are omnidirectional and cannot determine the specific location of an RFID tag among a group of packages in environments like trucking and warehousing.

Innovation Solution

A mobile device with a dual-antenna system, comprising a first omnidirectional antenna for detecting the presence of a transponder and a second directional antenna with a null pattern that sweeps to determine the direction of the transponder, allowing for precise location identification by avoiding signal reception when the null is directed towards the tag.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an omnidirectional antenna is used for RFID reading, then the reader can detect transponders in all directions, but the reader cannot determine the specific location or direction of the transponder

Engineering Contradiction:

Improveomnidirectional detection capabilityVSAvoiddirection determination accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent divides the single omnidirectional antenna function into two separate antennas: an omnidirectional antenna for detecting transponder presence in all directions, and a directional antenna with null pattern for determining the specific direction. This segmentation allows each antenna to specialize in one function, resolving the contradiction between omnidirectional coverage and directional precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using a directional antenna that maximizes signal in one direction, the patent employs a directional antenna with a null pattern that minimizes signal in a specific direction. By detecting where the signal null occurs (where no signal is received), the system determines the transponder's direction. This inverted approach—detecting absence rather than presence of signal—enables precise directional determination while maintaining omnidirectional scanning capability.

Inventive Principle:

Principle #13The other way round (Inversion)

2Measurement precision

If a directional antenna with null pattern is used to determine direction, then angular resolution is improved, but the antenna cannot detect transponders in all directions simultaneously

Engineering Contradiction:

Improveangular resolutionVSAvoidomnidirectional coverage

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent combines the omnidirectional antenna and directional null-pattern antenna into a single RFID reader system. The omnidirectional antenna provides comprehensive coverage by detecting transponders in all directions, while the directional antenna provides precise angular resolution by identifying the specific direction through its null pattern. The combination of these two antennas resolves the contradiction between omnidirectional coverage and angular resolution.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The omnidirectional antenna performs preliminary detection to identify the general presence and approximate location of transponders. Once a transponder is detected, the directional antenna is activated to precisely determine its direction by scanning for the null pattern. This preliminary action by the omnidirectional antenna guides the subsequent precise measurement by the directional antenna, efficiently resolving the contradiction between broad coverage and precise measurement.

Inventive Principle:

Principle #10Preliminary 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

Enables accurate location determination of RFID tags within a larger group by using the omnidirectional antenna for initial presence detection and the directional null antenna for precise direction-finding, improving angular resolution and facilitating the identification of specific tags.

Implementation Method 1

a second antenna comprising a directional radiation pattern and that is configured to sweep the area to determine a direction of the transponder

Methodology Applied

Scientific EffectAntenna radiation pattern with null:

Data Source

PatentUS10289877B2Directional antenna for RFID tag finder

Publication Date: 2019.05.14 HAND HELD PRODS INC

AI summary

A system may include a mobile device comprising an antenna system. The antenna system may include a first antenna to determine a presence of a transponder within an area and a second antenna comprising a directional radiation pattern and that is configured to sweep the area to determine a direction of the transponder. The first antenna may be separate from the second antenna.