Study On Technology Of Millimeter Wave Planar Endfire Antenna

With the rapid technological development in the wireless communication,the resources of the lower microwave band become increasingly crowded.What is more,the interference effects among various applications become more and more serious.As a conclusion,the operating frequency range of the wireless communication system is developing towards to the higher band,especially the millimeter wave.Many countries have invested a lot of manpower and money in the research and development of the millimeter wave communication.The 45 GHz band has obtained the extensive attention of China and other countries because of its unique advantages.With the completion of the deployment and maturation of the fourth generation mobile communication technology,the development and exploration of the fifth generation mobile communication has obtained more and more attention.Many countries have gradually released the frequency planning of the fifth generation mobile communication technology in the millimeter wave.The millimeter wave will become more and more important in wireless communication in the future.In this dissertation,considering the requirements of millimeter wave antenna miniaturization,wideband,high gain and easy integration,three planar endfire antennas with high performance are analyzed and designed.The study of this dissertation can be summarized as the following four aspects.(1)The research background and development status of the millimeter wave planar endfire antennas are analyzed.What is more,the antenna theory involved in this dissertation is introduced and summarized,which lays a theoretical foundation for the follow-up research.(2)The study of the log-periodic dipole array antenna to enhance the directivity is carried out.Based on the theory and principle of the log-periodic dipole array antenna,the method,which is used to enhance the directivity of the antenna,is proposed from two aspects.On the one hand,based on the principle of the quasi-Yagi and the bow-tie antenna,the bow-tie directors are added in the radiation direction.The directivity of the antenna is increased by the couple-interaction between the bow-tie directors and log-periodic cell and the guiding effect of the director cell on the antenna radiation energy in the radiation direction of the antenna.On the other hand,the parasitic patches are added to increase the antenna gain by expanding the transverse radiation aperture of the antenna.The parasitic patches with the same structure and size of the directors are added on the left and right sides of the director cell for the log-periodic dipole array antenna.These patches construct the similar array structure with the director cells,which is used to improve the directivity of the log-periodic dipole array antenna.Based on the proposed improved method,the printed log-periodic dipole array antenna is designed and simulated.The actual antenna is manufactured based on the simulation model.It can be obtained from the test results that the designed antenna has good performance,which verifies the effectiveness of the proposed method.(3)The method to extend the bandwidth of the quasi-Yagi antenna is studied.According to the composition structure of the quasi-Yagi antenna,the method of extending the bandwidth is proposed from three aspects through analyzing the structure and principle of the Yagi-Uda antenna.Firstly,the wideband feed structure is analyzed.Through comparing all kinds of feeder structures,analyzing the characteristics and suitable occasions of all kinds of feeder structures,the Grounded Coplanar Waveguide,which has the advantage of the wideband,small size and little loss in the millimeter wave frequency,is chosen as the feed structure of the quasi-Yagi antenna.Secondly,the wideband driver dipoles are used to improve the bandwidth of the quasi-Yagi antenna.The bow-tie dipole is used to replace the original planar dipoles as the driver dipole of the quasi-Yagi antenna.The bandwidth of the quasiYagi antenna is expanded without changing the overall size of the antenna through rounding off the joint between the balanced double line and bow-tie dipole and the end of bow-tie driver dipole.In order to further improve the antenna gain,the wideband dual driver dipoles are used to increase the number of the resonant frequency of the driver dipole to expand the antenna bandwidth.Finally,the structure of the director is changed to increase the coupling between the director and the driver which will also affect the current distribution of the driver dipole,extending the bandwidth of the antenna.In order to verify the validity of the proposed approach,the corresponding wideband quasi-Yagi antenna is designed,simulated,manufactured and tested.The simulated and measured results are in good consistency which proves the effectiveness of the proposed method.(4)The method to increase the directivity of the tapered slotline antenna is researched.The structure and principle of the tapered slotline antenna are analyzed.Then,the method to enhance the directivity of tapered slotline antenna is put forward from three aspects.Firstly,based on the principle of the printed log-periodic dipole array antenna and the wideband quasi-Yagi antenna with multiple driver dipoles,the outside edge of the radiating patch of the tapered slotline antenna is changed to the structure of the dipoles whose length varies according to a scale factor like the log-periodic antenna without increasing the size of the antenna.In different frequency,different dipoles with different lengths resonate,which can enhance the directivity of the tapered slotline antenna in the direction of radiation.Secondly,the vertical rectangular slots are etched on the top of the radiating patch to guide more energy into the radiation direction,increasing the directivity of the tapered slotline antenna.Thirdly,because that the tapered slotline antenna is a planar endfire antenna as log-periodic dipole array antenna and quasi-Yagi antenna,the directors are added in the direction of the antenna radiation to improve the directivity of the antenna.In order to verify the effectiveness of the proposed methods,the antipodal exponentially tapered slotline antenna with high gain is designed,simulated,manufactured and tested.The simulated and measured results are in good consistency.The antenna has good impedance matching and radiation characteristics,which shows the effectiveness of the proposed method.