Microwave properties of diluted composites made of magnetic wires with giant magneto impedance effect

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Microwave properties of diluted composites made of magnetic wires with giant magneto impedance effect

Olivier Acher, Marc Ledieu, Olivier Reynet, Anne-Lise Adenot

To cite this version:

Olivier Acher, Marc Ledieu, Olivier Reynet, Anne-Lise Adenot. Microwave properties of diluted composites made of magnetic wires with giant magneto impedance effect. Magnetics Conference, 2003. INTERMAG 2003. IEEE International, Mar 2003, France. pp.10.1109/INTMAG.2003.1230313,

�10.1109/INTMAG.2003.1230313�. �hal-00911564�

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MICROWAVE PROPERTIES O F DILUTED COMPOSITES M A D E OF MAGNETIC WIRES W I T H GlANT MAGNETO IMPEDANCE EFFECT

0. Acher, M. Ledieu, 0. Reynct, and A.-L. Adenot C E A Le Ripault, BP16. F-37260 Mom, France lntruductivn

The possibility of engineering microwave composites with new and attractive propenies has artrocfed considerable attention. since the Dioneerine. work of Pendrv I I I and Smith I2 I. These

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composites have n negative refraction index due to a negative permeability and permittivity.

They arc denominated either left-hmded materials. negative index materials or mcunidcridl*. Thc ticgativc pcnnillivily pnrpcrlic.; are cnmnionly achicvcd thmugh a w i i r media consisting of an a m y of wires.

We report here significant advances on wire media based on magnetic m i c m w i m . We have estahlished the theoretical description of wire media made o f WilgneliC wires, rupponed ^{h y} experimental results [3]. In particular. we show that there i s

close link between the Giant Magneto lmpcdance Errcecl (GMI) in individual wiics, and the kc-spacc niicmwwc propenies of the composite wire media. A s a consequence. the extended knowledge on FMI materials and effects developed in recent years may he readily used to design wire media with new dielectric properties. For example, the demonstration of composites with tuneahle dielectric consunt under a static magnetic field i s easily described using the G M I approach.

Ex~erimental details and results

Lattices of continuom parallel wires have been manufactured using several types of amorphous glass-coillcd CoFcSiB m i c m w i i n with diftcrcnt magtictic propcnics. 7 h c

of the lattices are 3Wmmx300mm. Free-space reflection and transmission microwave measurements have been performed to detcrmine the effective permittivity of these composites, in

configuration sketched on Fig. I. The permittivity o f a wire media mode of wires with an axial magnetization i s reported in fig. 2. Unlike traditional metallic lattices [I], thc diclcctric rcsponrc is clearly rwonant. 1 . a ~ ~ ncgativc pcrniittivitics arc ohtaincd in thc 4.5 to I I GHz range. I n contrast. wire media made using wires with circumferential magnetization exhibit propenies similar to h i t of metiillic non magnetic wire media.

Analvlical model

A n elcctric ticld i\ produccd hy tlic micnwirc in rcc’ipoiisc

thc incidcnt planc

Thc effective permittivity o f the wire media is the ratio of the spatial average o f electrical displacement <D>, over thc sp;ai;tl ovenige of the elcclric field <E>. <D> is cssentiiilly ilflecled by the conductivity of the wire over the \kin depth. This leads to

ftctor in the exprer~ion of t h e effective permittivity that is dependent on the ratio of the microwave impedance over D C resistance. This is the same quantity that cm be mcerured thmugh CMI experiments. <O is affected by the long range radiation of the different wires in the whole space, leadinx l o a fistor similar lo that established for mefitllic non magnetic wires.

where ZiRa i s the GMl ratio, A an

only dependent o n the genmclr).. f the \nlunx rraciiw or wire and

the uanductivity or the wire. A wnmpariaon hetween theory and mensurements is reponed in ti$. 2. A g d apeement is nchicvcd.

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Radar nhwrbing

2 4 0 9 10 12 Id 16 IR

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Figure 2 : Compnnson hetween calculated and mcasured Dcrmittivitv ora wire medium. Illhe Figure I : wire ,medium and

polarization of interest. miignctostrictiori cocfficicnr of thc alloy i5 posirivc.

Dielectric resnonse tuned usins a static mametic field

It has been demonstrated that the permittivity of these composites can he tuned by applying a static magnetic field. Permittivity me;si~rementa performed in a trmsmirsion line

reported

fig. (4).

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References

( I ] J . B. Pendry, A. J. Holden, D. J. Rohhins. and W. J. Stewart, J. Phys. Condens. Matter.

10.4785 (1YY8)

121 D. Smith. W. Padillil. D. Vier, S. Ncmot-Nawerand S. Schull,.. Phys. Rev. Lcll. R4,41R4 (2000).

(31 0. Reynet, A.-L. Adenot, S. Deprot, 0. Acher and M. htrach. Phys. Rev. B 66.0Y44 12 (2002)

fie effecliv~permiltivily ofthe wire media i s shown to be :