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Anisotropic Z-type hexagonal ferrite and antenna using same

A hexagonal ferrite, anisotropic technology, applied in the direction of antenna, inorganic material magnetic, electrical components, etc., can solve the problem of using frequency limit, reduce antenna bandwidth, low impedance, etc., achieve high cut-off frequency, high dielectric constant , the effect of high permeability

Inactive Publication Date: 2010-08-11
SOUTHWEST JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the use of high dielectric constant materials to design miniaturized antennas has the following disadvantages: 1. The dielectric region of high dielectric constant is capacitive so that most of the field is confined, thereby reducing the bandwidth of the antenna
2. The intrinsic impedance of materials with high dielectric constant is usually relatively low, which makes the impedance matching of the antenna more difficult
[0005] Due to the unsatisfactory performance of other types of ferrite magnetic materials in the ultra-high frequency and microwave frequency bands, the use of ferrite materials in antennas is still relatively small, and ferrite materials are mainly used as loop coil antennas. The working frequency of the magnetic core and the antenna is also relatively low
When using ferrite magnetic materials for microstrip antennas, such as spinel ferrite, according to the Snoek formula, the maximum use frequency of Mn-Zn and Ni-Zn ferrite with spinel structure is limited by the cubic crystal structure limits
At present, Ni-Zn ferrite is a soft ferrite material widely used in the medium and high frequency band up to 100MHz, but in the frequency band exceeding 200MHz, the skin effect and eddy current loss caused by electromagnetic induction will lead to significant performance degradation, and because its material The limitation of its own cutoff frequency makes it impossible to use

Method used

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  • Anisotropic Z-type hexagonal ferrite and antenna using same
  • Anisotropic Z-type hexagonal ferrite and antenna using same
  • Anisotropic Z-type hexagonal ferrite and antenna using same

Examples

Experimental program
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Effect test

Embodiment 1

[0014] Example 1 (Ba 3 Co 2 Fe 24 O 41 )

[0015] The material uses metal oxides and carbonates with purity higher than 99% as raw materials, BaCO 3 , Co 2 O 3 And Fe 2 O 3 According to molecular formula weight ratio, using conventional ceramic technology, pre-sintering temperature 1180~1240℃, sintering temperature 1200~1280℃, adding trace Bi 2 O 3 And MnCO 3 Adjust (addition amount is 0.005~0.01% by weight), the real part of dielectric constant ε'is about 8~18, the real part of complex permeability μ'is about 5~10, in the frequency range of 100MHz~2G The imaginary part ε", μ" that can maintain the dielectric constant and permeability is small, that is, the loss of the Z-type ferrite is small, and the loss tangent angle is generally less than 0.06. Moreover, the present invention can also control the process and formula to make the anisotropic Z-type hexagonal ferrite reach a certain frequency

Embodiment 2

[0016] Example 2 (Using this material to design UHF RFID microstrip antenna)

[0017] Using the process and material of Example 1 (anisotropic Z-type hexagonal ferrite ε′=17, μ′=7, tgδ ε =0.01, tgδ μ =0.05) Manufacturing UHF RFID microstrip antenna for magnetic substrate, the antenna structure is as figure 1 with figure 2 As shown in the figure, 1 is the grounding plate, 2 is the rectangular patch, 3 is the feed point, 4 is the anisotropic Z-shaped hexagonal ferrite, and 5 is the feed probe; patch size L=16mm, W= 18mm, the ground plate LG=WG=30mm.

[0018] The resulting antenna S 11 Curve like image 3 (Antenna bandwidth (S 11 <-10dB) is 918MHz~939MHz); the antenna gain is about 1.76dBi.

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Abstract

The invention discloses an anisotropic Z-type hexagonal ferrite which is suitable for high and ultrahigh frequency band antennas and has the components: Ba3Me2Fe24O41, wherein Me is one of Co, Zn, Ni, Mg and Cu. The sintering temperature of the anisotropic Z-type hexagonal ferrite is controlled to be from 1150 DEG C to 1300 DEG C; trace oxides are added for regulating a dielectric constant, permeability and the sintering temperature; therefore, a real part epsilon' of the dielectric constant is from 1 to 20; a real part mu' of complex permeability is from 1 to 10; and the dielectric constant or the permeability is basically unchanged as certain values within a certain frequency band of 100 MHz to 3 GHz. The hexagonal ferrite has high cut-off frequency, high dielectric constant and high permeability due to higher magnetic anisotropy field, and can be applied to miniaturization of the sizes of the high and ultrahigh frequency band antennas.

Description

Technical field [0001] The invention belongs to the field of wireless communication antennas, especially microstrip antenna manufacturing. Background technique [0002] Due to the rapid development of wireless communication technology, various types of mobile communication systems working in different frequency bands have emerged. For example, wireless communication systems DCS1800 (1.71~1.88GHz), PCS1900 (1.85~1.99GHz), WCDMA (1.92~2.17GHz), UMTS (1.92~2.17GHz), WLAN (2.4~2.484GHz), DMB and DVB-H( 170~800MHz) and so on. In addition, for the RFID system in the Internet of Things that has attracted much attention in recent years and has developed rapidly, various regions of the world also have different UHF operating frequency bands, which are 866-869MHz in Europe, 902-928MHz in North and South America, and 840-845MHz in my country. 920~925MHz, while Japan and some Asian countries are 950~956MHz. It can be seen that the antenna working frequency band in the RFID system can cover...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F1/11C04B35/64H01Q13/08
Inventor 冯全源
Owner SOUTHWEST JIAOTONG UNIV
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