Research And Design Of Compact Multiband Antenna For Handsets Application

With the rapid development of wireless communication systems,communication systems have experienced rapid development from 1G to 4G,and will move towards 5G in the future.The development of wireless communication systems also has a profound impact on mobile phone terminals.The communication speed of mobile phone terminals becomes faster,and its functions become more diversified.As an important component of the mobile phone terminal,the size and performance of the mobile phone antenna has an important influence on the overall appearance and user experience of the mobile phone.In the early stage of mobile phone development,mobile phones were only used as a tool for daily communication.People often pay more attention to its communication performance when they choose to buy mobile phones.In order to satisfy the needs of consumers,the traditional mobile phone antenna must be able to cover a wide commercial communication band,and achieve the great far-field radiation performance that meets the industrial standards.However,With the development of science and living standard,consumers pay more attention to the quality of products,including the more beautiful appearance of mobile phones.In order to improve the overall visual effect and touch feel of the mobile phone,the mobile phone is developing towards the direction of large screen and metal integration.On the one hand,for large-screen mobile phones,designers need to minimize the dimension of clearance to reserve more space for the screen and other components.However,the development of the communication system,the communication band is increasing and expanding,which will inevitably increase the space occupied by the mobile phone antenna.How to reduce the size of the clearance area while satisfying the normal communication of mobile phones has become a big problem in the design of large-screen mobile phones.On the other hand,for the metal-rimmed mobile phones,by loading the metal frame around the mobile phone,it will improve the overall mechanical strength and texture of the mobile phones to satisfy the aesthetic needs of the consumers.But its disadvantages can not be ignored.As a metal shielding structure,the metal frame encloses the internal antenna.The radiation signal of the internal antenna will be seriously interfered and weakened by the metal frame,so the comprehensive performance of the mobile phone will be greatly reduced.Therefore,in the design of mobile phone antenna with metal frame,how to solve the interference of metal frame to the built-in antenna signal is also a big problem for designers.Aiming at the two problems in the design of mobile phone antenna design process,this paper proposes different schemes and designs two corresponding antennas:1.In order to realize the miniaturization of the antenna clearance area and satisfy the the requirements of multi frequency points and wide band coverage,we design coupled feed mobile phone antenna based monopole structure.The monopole radiation branches of different shapes and different lengths are used in nested coupling,and lumped elements are added at the feed port to form a matching network,so that the designed antenna can achieve LTE / WWAN/Wi MAX bands coverage and good far-field radiation performance with a relatively small clearance area,which makes the designed antenna more competitive in 4G and future 5G wireless terminal applications.2.In order to solve the electromagnetic interference of external metal frame to internal antenna of metal frame mobile phone antenna,we design a metal frame mobile phone antenna,which could cover the LTE / WWAN frequency bands.The designed antenna is mainly divided into two parts: metal frame and built-in antenna.The substrate is surrounded by a rectangular metal frame.The metal frame and the internal antenna are coupled fed by an inverted L-shaped feeding strip.The metal frame is used to generate a low frequency resonant mode,and the internal antenna is used to generate a high frequency resonant mode.The basic structure of the proposed antenna in this design includes loop structure,slot structure and monopole structure.Firstly,many kinds of resonant modes are generated by coupling feed.Then by adjusting the length,shape and relative position of each radiation branch,the impedance matching of the whole antenna is improved,and the good performance of the antenna is realized.In addition to testing the basic performance parameters of traditional mobile phone antenna,the design also considers the influence of human body on the performance parameters of mobile phone antenna.By holding in different positions of mobile phones by human hand,we can observe the influence of antenna return loss,gain,efficiency and other different parameters at different positions.