Study On New Fourth Generation Mobile Communication Antenna

At present,the 4G communication network based on LTE technical standards coexist with 2G and 3G networks.Mobile communication services are distributed in many frequency bands,with relatively wide ranges of band distribution.The key technology of 4G communication is to realize high-quality antenna coverage of all these frequency bands for spatially limited mobile communication base stations and mobile terminals.At present,the mobile base station antenna usually adopts a combination of multiple antennas working in different frequency bands,and the mobile terminal usually uses an integrated design of multi-radiating elements.The current design results in issues such as radiation blind spots caused by antenna interference in the relatively small space inside the antenna system,relatively large gain differences when working in different bands,and increase in installation and post maintenance costs.Therefore,a multiband,multi-standard,single radiating element antenna design suitable for 4G communication system is of great significance.In the thesis,a series of innovative designs has been conducted for the 4G communication system macro base stations,the indoor distribution system,and antennas on the three types of mobile terminal platforms.The main research content and innovations include the following:1.Two types of compact balun are designed using the radiation cancellation mechanism of leakage current when folded into a quarter-wavelength structure caused by unbalanced port matching.Both types of balun have the microstrip structure with wide bands and are easy to fabricate.They can be used for the unbalance – balance conversion and impedance matching between the coaxial feeder and the dipole antenna on the other side of the antenna arm,in order to produce the multi-standard small antenna suitable for 4G communication applications.2.In this thesis,the dual-band dipole antenna construction of balun uses the open ends of the antenna arms for stepped shaping to achieve the current multipath radiation,broadening the antenna frequency band.Furthermore,the load capacitor is used to achieve band migration.A single radiating element mobile terminal antenna with a size of only 49 mm × 34 mm × 1.6mm that can over all bands of TD-LTE standard is designed.3.An aperture coupled dipole antenna is designed.In the design,the coupling between the seam and the microstrip enables the antenna-radiating mask to obtain balanced feed.A dumbbell-shaped seam,dumbbell-shaped microstrip-radiating element,and stepped feeder are designed to realize ultra-wide antenna.The antenna only has one radiating element,and the operating band can cover all service bands of 2G,3G,4G,Bluetooth,and WLAN except for GSM900 of 2G and service bands corresponding to the CDMA communication standard.The antenna size is only 52 mm × 18 mm × 1.6mm,which can be used as an internal antenna for the mobile terminal.4.An indoor distributed system with omnidirectional ceiling antenna is designed.The design uses monopole radiation arm forming and the meander technology to realize ultra-wideband antenna,which can cover all service bands of 3G,4G,and WLAN,as well as some 2G bands.The antenna has only one radiating element,which overcomes the disadvantages of poor radiation directivity and gain instability caused by other sub-system multi-antenna combinations.Simulation results in the background of simulated buildings show that the antenna performance is relatively satisfactory.5.A wall-mounted directional antenna for 4G distributed system is designed.The oscillator arms of the antenna are on different sides,so that the structure has a small size.Based on the design concept of the Yagi-Uda antenna,four directors are designed for the antenna to achieve high gain.Simulation results from simulation within a building environment show relatively satisfactory radiation characteristics.6.A phase shifter realized by equivalent change in dielectric constant by sliding the dielectric block is designed using the effect of change in dielectric constant of the medium on the electromagnetic wavelength.Through the phase shifter,the intelligent regulation of radiation directions of antenna arrays suitable for 4G communication is further achieved.In this design,the antenna array has relatively large tolerance for the sliding wear of the dielectric block,which can effectively improve the lifespan of the phase shifter,which in turn reduces operating costs.