| Since 1901,when the first wireless communications came true by Marconi,so many wireless products have emerged,which makes people’s lives become more and more convenient.The rapid development of wireless communication technology and the wide range of the application mean scientific and technological progress and the needs for the improvement of the quality of people’s life.In wireless communication system,antenna is a key device,which is responsible for receiving and transmitting electromagnetic waves.The performance parameters of the antenna directly affect the operation of the whole system.There are many kinds of antennas,different applications have the corresponding antenna to be equipped with.The quardrifilar helix antenna not only has good circular polarization performance,but also has high sensitivity,so it is very suitable to be used as a receiving antenna in GPS(Global Positioning System).As we all know,with the development of wireless communication technology,the global positioning system has been not limited to military applications,and has been used into the social development,economic development and other fields gradually.More and more widely application usually means higher and higher standard,and more and more in-depth research will be needed.Especially for the antenna which plays a decisive role in the signal reception in systems.Based on these,through combined with ceramic,LTCC and other new technologies,the research and design of the quardrifilar helix antenna are made in this paper.Firstly,the background of the study is presented in detail and a detailed analysis of the theoretical basis of the quardrifilar helix antenna is given.To achieve excellent circular polarization,the quardrifilar helix antenna which is four-arm structure needs the feed with the same amplitude and the orthogonal phase,the antenna design project not only to consider the characteristics of antenna,the feed network is also an important problem.Another noteworthy feature is the combination of new materials and new technologies,which is the antenna development trend.Secondly,this paper introduces a kind of a small quadrifilar helix antenna by using a ceramic dielectric column as the medium load.On the road for the miniaturization of antenna,the high dielectric constant ceramic material loading is an important milepost.On this basis,this design combines a method,adding short arms beside the main radiation arms to broadening the bandwidth of the antenna.Through simulation and optimization,the antenna is only the size of a cylinder with the diameter of 10mm,height of 12mm,the half power beam width can reach more than 120?,and it’s bandwidth up to 15%.Besides,it achieves a good right-hand circular polarization characteristic.After that,this paper designs a kind of square printed quadrifilar helix antenna.The antenna give up the traditional column winding structure,then the four arms are printed on the adjacent four faces of the cube.This design combines the good circular polarization characteristic of quadrifilar helix antenna and the advantages of easy processing and product of microstrip antenna.At the same time,in order to increase the input impedance of the antenna,the radiation arm of the quadrifilar helix antenna adopts a spiral inverted F antenna(IFA).Then we have to feed the antenna with the same amplitude and phase difference of 90~o.Through the simulation and optimization,front to back ratio more than20dB,and AR is less than 3dB in the angle of?90?,so the antenna realize a good polarization performance.The results of physical test and simulation results are basically the same.This square printed quadrifilar helix antenna is a good choice for GPS receiving equipment.Finally,a feed network with a working bandwidth of 1.34GHz-1.73GHz for quadrifilar helix antenna is designed,which combined with two 3dB directional coupler(90~ophase shift)and a Marchand balun(180~ophase shift).The LTCC technology not only effectively realizes the miniaturization of the feed network,but also improves the bandwidth,accuracy and reliability.After the optimization,the feed network can operate in a wide range of1.34GHz-1.73GHz,and has a good range of amplitude and phase response balance for the application of the quadrifilar helix antenna. |
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