Research And Application Of Miniaturized Low-frequency Metamaterials

Electromagnetic metamaterials as a artificial materials has been concerned widely and studied deeply in recent years.Because it has a lot of special properties which have great value, now widely used in communications, radar and other fields. However,putting the electromagnetic material into the production of a device is affected by the frequency.As you known, the large size of low-frequency electromagnetic material limits its application, although there is lots of research on the low-frequency electromagnetic material in these wave band such as GHz, THz,lightwave,MMs design in MHz band is still a difficult because it limited by the unit dimensions and dielectric loss of the resonant MMs model. So look for a simple and effective design on miniaturization is particularly important.First, this paper introduces the background of the researching,the developmental status of electromagnetic metamaterials and several common electromagnetic metamaterials, and then for the resonant electromagnetic metamaterial introduces its physical mechanism of receiving equivalent constitutive parameters,and several method of researching on selectromagnetic metamaterials, including S-parameters inversion and equivalent circuit.In addition, it designed two single negative material by CST simulation software,one is simple split ring resonator (SRR) structure to achieve magnetic resonance,the other is simple "1" type resonant structure to achieve electrical resonance.Both structures constituted by the metal cladding layer and the dielectric substrate layer,by S-parameter analysis to verify its single negative characteristic.By making use of analytical methods of equivalent circuit model and analyzing their surface current, lumped elements are loaded in their specific position. By changing the size of lumped parameter, the structure achieved a adjustable resonance frequency, a low-frequency absorbing characteristic and a optional low-frequency characteristic in the same size.Then,it proposed composite structures on the basis of the previous two simple electrical and magnetic resonant structure,the first design is a double negative materials which loaded by a single adjustable capacitor, this structure is composed by a metallic copper strips which provides negative permittivity and the SRR which provides negative permeability.Moreover,it designed adjustable double negative materials loaded double-capacitor that is composed by a copper strips and a square ring SRR each loaded with a capacitive element to achieve the double negative characteristics of the material.Then,we combined the structure of three layers metal copper strip to design a adjustable frequency absorbing material,each copper strips was loaded with a resistor element used to achieve absorbing characteristics and a capacitive element used to achieve frequency adjustable characteristics.The absorbing coefficient of the structure was controlled by adjusting the resistance we loaded and the spacing between neighboring copper strips.Finally,we designed another absorbing materials with adjustable frequency by combining copper strip and SRR ring.Compared with multilayer structure,this model has lager absorption coefficient close to 1,but the defect is that the bandwidth of the maximum absorption peak is narrow.By inverting the S-parameter,we foud that it is an effective means to miniaturize the size of the materials by loading lumped elements on it and using loaded resistor element is an effective way to achieve absorbing characteristic.The researching on the miniaturized electromagnetic metamaterials makes it having a broader application prospect and researching value.