| With the rapid growth of wireless communication technology,the demand of miniaturizated telecommunication devices and high communication transmission rate is increasing rapidly.In wireless communication systems,antenna is a key component which plays an important role in communication quality.Thus,to meet the needs of wireless communication system,the study of miniaturized,broadband and high-performance antennas has become a hotspot.Novel ferrite materials have attracted extensive attention due to that both the magnetic and dielectric properties of ferrite materials can be utilized to optimize antenna performance.Compared with no-magnetic substrate,the magnetic property of the ferrite material makes antenna design more flexible and diverse,and provides more possibilities for the realization of miniaturized,broadband and high-performance antennas.The application of ferrite magneto-dielectric materials in several antennas with different structures is studied in detail,and the influence of ferrite's dielectric and magnetic property on antenna performance is discussed.We also explored the influence mechanism of ferrite materials on antenna performance.The main work of this paper is as follows:1.Firstly,the role of ferrite partial loading technology in microstrip antenna is studied.By embedding the ferrite materials into the antenna substrate and combining the slotting technique and the floor extension structure,the antenna miniaturization is achieved.The influence of the ferrite size and the different embedding position on the antenna miniaturization is studied.Furthermore,for improving the radiation performance of the antenna,the influence of the bias magnetic field is studied as well.The results show that by utlizing the appropriate strength of the bias magnetic field,the ferrite material can improve the radiation gain of the antenna.The dimension of the desgined antenna is 0.101?0.433×0.108?0.433×0.022?0.433(?0.433 is the wavelength corresponding to 0.433 GHz in air),and the gain is 1.3 d Bi.2.In order to integrate the ferrite loading technology into the antenna design through a low-cost,low complexity and high degree of freedom way,this paper explores the combination of the dual-layer microstrip antenna structure and the ferrite partial loading technology.At first,a multi-frequency microstrip antenna is designed based on the slotting technology,the branch loading technology and the stacking technology.Air is used as the medium between the superstrate and the radiation patch.Studies reveal that the antenna performances can be effectively and flexibly modulated by the dimension,location and permittivity of the loaded ferrite materials in air layer without affecting antenna profile.The measured-10 d B impedance bandwidth of the antenna is 693 MHz(2.033-2.726 GHz),the relative bandwidth is about 30%,and the peak gain is 6.14 d Bi.3.A compact antipodal planar antenna based on ferrite substrate is presented.Compared with the antipodal planar antenna using FR-4 substrate,the proposed ferrite antenna shows wider bandwidth.In UHF band,the high permittivity and permeability of the ferrite material make the antenna have a lower operating frequency.Then,the operating frequency of the ferrite antenna is further expanded to lower frequency band by the U-shaped slots,and the optimized antenna size is 0.2?0.7×0.2?0.7×0.66 mm(?0.7 is the wavelength corresponding to0.7 GHz in air).The measured-10 d B bandwidth of the antipodal antenna is 0.657-3.8 GHz.4.Based on the frequency-dependent magnetic property of the ferrite,a harmonic suppressed ladder type antipodal Vivaldi ferrite antenna is proposed.Compared with the coplanar waveguide(CPW)feeding antenna and the exponential slot antenna,the proposed antenna exhibits better impedance matching,better harmonic suppression effect and higher gain,and also shows omnidirectional radiation property in the xoz plane.The size of the fabricated antenna is 0.15?0.9×0.165?0.9×0.006?0.9(?0.9 is the wavelength corresponding to0.9 GHz),and the measured suppression frequency range of the antenna is 1-2.5 GHz with-10 d Bi gain as the standard.The total research results show that the magneto-dielectric ferrite is an excellent material for realizing miniaturized and broadband antenna.The magnetic property of the ferrite materials provides new methods for designing high performance antennas.There is no doubt that the proposed ferrite antennas with new characteristics have a considerable development prospect in emerging wireless communication fields. |
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