| With the rapid development and progress of the information era,Wireless systems are developing toward miniaturization,integration,high performance and multi-function.The antenna as the physical carrier of communication signal,its development also required to be small size,multi band and broadband.Owe to the different characteristics as low loss,broadband,unusual phase constant and so on,composite right/left-handed?CRLH?transmission line has been widely applied in microwave devices and antenna design.Based on the application of CRLH transmission line in the antenna,this paper explores the way to realize miniaturization and broadband antenna.The main work of this thesis can be list as follows:1.This paper briefly introduces the basic concepts of metamaterials and CRLH and points out its important research significance,and then organizes the domestic and foreign research achievements about the meta-material antenna.Then the electromagnetic characteristics of Meta-materials,the equations of left-handed materials and right-handed materials,the basic principle of CRLH and zero-order resonator have been studied in detail,which lays a solid foundation for the antenna design.2.The equivalent circuit parameters extraction method used for composite right/left-handed transmission line is improved in this paper because the traditional parameters extraction method can not accurately describe the CRLH transmission line structure of multi unit,and the results will fluctuate in a certain frequency range.Besides,two kinds of CRLH transmission lines are designed to verify the proposed method.The experimental results show that this new extraction method not only takes into account the coupling effect between the units of the CRLH transmission line and the loss of the transmission line which makes the extracted results are accurate,but also has the advantage of simple in calculation and suitable for various CRLH transmission line structure.3.The relations between zero order resonance antenna bandwidth and capacitance and inductance of CRLH transmission line is studied and the bandwidth formula based on equivalent circuit parameters is derived in this paper.By this formula,the wide bandwidth antenna based on CRLH transmission line is designed.Then,CRLH transmission line structure of parallel patch is analyzed based on parameter extraction method.The analysis focus on the relationship between the physical structure of CRLH transmission line and equivalent circuit parameters,and gives the trend of equivalent circuit parameters corresponding to the change of various physical structures.According to the parameters of the equivalent circuit to calculate the resonant bandwidth of the antenna,and comparing results with the antenna simulation results,it shows that the calculation results of bandwidth formula and simulation results are consistent,which illustrates that the bandwidth formula has certain reliability.Finally,the initial structure of the antenna is optimized according to the correlation between the bandwidth and the physical structure achieves the purpose of bandwidth extension.It provides a new guidance of designing wide bandwidth antenna based on CRLH tranmission line.4.A wideband LTE antenna based on CRLH transmission line has been proposed in this paper.The antenna is designed on the basis of the monopole loaded CRLH transmission line of the upper and lower patch structure.The introduction of monopole can make the antenna not only resonates in the low frequency,but also integrates the adjacent bands to expand the bandwidth in high frequency.The test results show,under the condition of S11<-10 dB,the antenna cover the band 680MHz910 MHz and 1.9 GHz2.7 GHz,which satisfies the communication needs of LTE mobile phone antenna.And the size of the antenna is only60 mm*18 mm*1 mm,it proves the proposed antenna has compact size and wide bandwidth. |
PDF Full Text Request