Phased Array Antenna Null Steering for RFID Interference

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Solution Overview

Problem

Existing tag communication systems face interference issues due to radio waves emitted by multiple tag communication devices, which can lead to reduced system speed, increased costs, and limited flexibility in arrangement, especially when devices are moved or rearranged.

Innovation Solution

The system employs array antennas with controlled directivity, where nulls are positioned to oppose each other and main lobes are directed away from interfering paths, using phased array antennas with phase shifters to minimize interference between tag communication devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If multiple tag communication devices are arranged to perform wireless communication, then communication coverage is improved, but radio wave interference occurs between devices

Engineering Contradiction:

Improvecommunication coverageVSAvoidradio wave interference

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating directional radiation patterns with distinct main lobes and nulls for each antenna. Each antenna transmits radio waves with enhanced intensity in specific directions (main lobes) while creating zero-intensity regions (nulls) in other directions. This allows multiple antennas to operate simultaneously in different spatial zones without interfering with each other, thus improving communication coverage while preventing interference.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent resolves the interference problem by transitioning from a two-dimensional planar arrangement to a three-dimensional spatial arrangement of radiation patterns. By controlling the vertical and horizontal radiation characteristics to form specific main lobes and nulls, the system utilizes spatial dimensionality to separate communication channels. This allows multiple devices to coexist in the same physical space by occupying different spatial radiation zones, thereby expanding coverage without causing interference.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If synchronization methods are used to prevent interference, then interference is reduced, but system speed is reduced due to time division communication

Engineering Contradiction:

ImproveinterferenceVSAvoidsystem speed

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent enables continuous useful action by allowing all tag communication devices to transmit radio waves simultaneously without time division. The directional control of main lobes and nulls ensures that simultaneous transmissions do not cause interference, as each device's radiation is confined to specific spatial zones. This eliminates the need for time-synchronized transmission gaps, maintaining maximum system speed while preventing interference through spatial separation rather than temporal separation.

Inventive Principle:

Principle #20Continuity of useful action

3Object-affected harmful factors

If antenna direction adjustment methods are used, then interference is prevented, but arrangement flexibility is reduced and additional costs are incurred

Engineering Contradiction:

ImproveinterferenceVSAvoidarrangement flexibility

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics by making the radiation pattern adjustable and adaptable rather than fixed. The system can dynamically control the direction and shape of main lobes and nulls based on the actual spatial arrangement of devices. This dynamic control allows the system to adapt to various deployment scenarios and device positions without requiring physical reconfiguration or additional hardware, thus maintaining arrangement flexibility while preventing interference.

Inventive Principle:

Principle #15Dynamics

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 reduces mutual interference between tag communication devices, enhancing system reliability and flexibility by ensuring that radio waves are directed away from interfering paths, even when devices are moved or rearranged.

Implementation Method 1

the system employs array antennas with controlled directivity, where nulls are positioned to oppose each other and main lobes are directed away from interfering paths, using phased array antennas with phase shifters to minimize interference between tag communication devices

Methodology Applied

Scientific EffectPhased Array:

Implementation Method 2

plural tag communication devices for performing wireless communication with a RFID tag attached to a moving body through a radio wave

Methodology Applied

Scientific EffectElectromagnetic Radiation:

Data Source

PatentUS7701351B2Tag communication system having a controlled antenna array to prevent interference

Publication Date: 2010.04.20 OMRON CORP

AI summary

The invention provides a tag communication system, an interference preventing method and a tag communication controller suitable for prevention of a radio wave interference able to be caused by radio waves mutually emitted when plural tag communication devices are arranged. Plural reader-writers are oppositely arranged through a belt conveyer for conveying an article. A null of the reader-writer is opposed to a null of the reader-writer. A null of the reader-writer is opposed to a null of the reader-writer. Main lobes are directed to a direction causing no mutual interference.