Folded Dipole Antenna Using Hexagonal Ferrite for UHF RF Tags
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Solution Overview
Problem
Conventional RF tags operating in the UHF band are too large to be attached to small articles and suffer from frequency characteristic fluctuations when near dielectric materials, leading to poor durability and limited application, especially under severe conditions.
Innovation Solution
A folded dipole antenna using hexagonal ferrite as a magnetic material with a radiation and reflection element structure, allowing for a smaller size and improved frequency stability when attached to various materials, including metals and dielectrics, enabling reliable communication and high heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional UHF band antenna is used in an RF tag, then the antenna can communicate at a distance of several meters or more, but the antenna size becomes too large to be attached to small articles
Solution Approach 1:
The patent changes the magnetic permeability parameter by introducing a magnetic material (ferrite) into the antenna structure. This parameter change allows the antenna to achieve the same electrical length and radiation performance with a physically smaller dimension, resolving the contradiction between communication distance and antenna size.
Solution Approach 2:
The patent uses a composite structure combining conventional antenna materials with magnetic material (ferrite). This composite approach enables the antenna to maintain its radiation characteristics while reducing its physical size, allowing attachment to small articles while preserving UHF band communication capability.
2Adaptability or versatility
If the antenna is disposed close to or attached to dielectric materials such as resin, metal, paper, or water, then the RF tag can be attached to various articles, but the frequency characteristics of the feeding point impedance fluctuate and reading characteristics deteriorate
Solution Approach 1:
The introduction of magnetic material changes the electromagnetic parameters of the antenna system, making the frequency characteristics less sensitive to variations in surrounding dielectric materials. This parameter change stabilizes the feeding point impedance across different attachment environments.
Solution Approach 2:
The patent converts the harmful effect of dielectric materials (which cause impedance fluctuation) into a beneficial configuration by using magnetic material that is less sensitive to dielectric interference. This allows the antenna to maintain stable frequency characteristics even when attached to various articles with different dielectric properties.
3Length of moving object
If the antenna size is reduced to attach to small articles, then the RF tag can be used on smaller objects, but the frequency characteristics become more sensitive to ambient environment and durability decreases
Solution Approach 1:
The use of magnetic material (ferrite) in the antenna structure provides inherent environmental stability. This composite approach creates an antenna that is both small in size and resistant to environmental factors such as humidity and temperature variations, improving durability while maintaining compact dimensions.
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
The RF tag achieves a significant size reduction, enhanced communication reliability, and improved environmental resistance, allowing it to be mounted on printed electronic circuit boards using standard methods like reflow soldering, with minimal impact from ambient environments.
Implementation Method 1
an antenna for communicating the data with an outside are mounted on a flat thin base sheet formed of a resin, a paper or the like. The RF tag is attached to an article to be managed, and communicates necessary information data with a reader/writer using a radio wave.
Implementation Method 2
a hexagonal ferrite has been proposed as a magnetic material that can be used in a UHF band. The folded dipole antenna comprising a magnetic material in which a radiation element and a reflection element each having a folded dipole structure are disposed
Data Source
AI summary
The present invention relates to a folded dipole antenna comprising a magnetic material comprising a hexagonal Z-type ferrite and/or a hexagonal Y-type ferrite as a main component in which a radiation element and a reflection element each having a folded dipole structure are disposed, and an RF tag comprising the folded dipole antenna and an IC chip connected to the folded dipole antenna. The RF tag according to the present invention has a smaller size than that of the conventional RF tags and is not susceptible to adverse influence from ambient environments, and can be operated at an UHF band or surrounding frequency bands thereof.