The Study And Design Of Miniaturized Multiband Microstrip Antennas

With the continuous improvement of the level of science and technology,people have a demand for miniaturization and versatility of wireless communication systems.Antennas,as energy converters in wireless communication systems,play an important role in converting guided waves and free space waves to each other.Due to the high degree of integration of the functions of the wireless communication system,the electronic equipment therein requires the installation of multiple antennas,and the miniaturization of the equipment leads to a smaller and smaller distance between the antennas,which results in strong electromagnetic interference between the antennas,and affects the entire system working properly.In order to solve this problem,a solution for installing a miniaturized multi-band microstrip antenna is proposed.Based on the above background,this paper has carried out research and design work on miniaturized multi-band microstrip antennas,and the main research contents are as following:(1)Contrary to the complex structure and large size of the current multi-band microstrip antenna,this paper designs a miniaturized triple-band microstrip antenna based on a multibranch structure.The antenna mainly adopts bent branches to achieve antenna's miniaturization.By increasing the number of branches to increase the effective path of the current,multiple resonance points are generated and a multi-band design is realized.The proposed antenna adopts microstrip feed and the three branches of the antenna generate three resonant frequency bands,covering the sub-band 2.4-2.484 GHz of WLAN,WiMAX(3.3-3.69 GHz)and the 5G band(3.3-3.6GHz,4.8-5.0GHz),which is newly allocated by the Ministry of Industry in 2017.Modeling and Simulation of Antennas through High Frequency Structure Simulation,results show that the antenna in the working band has S11 <-10 dB,VSWR <2,and the input impedance Z11 is equal to about 50 Ohm,so the antenna has a good impedance matching characteristics;at the same time,the antenna in the operating frequency band has omnidirectional radiation characteristics.(2)A like-rivet miniaturized dual-band microstrip antenna with smaller size and simpler structure is proposed.The slotted semicircular patch is used to take place of the traditional rectangular patch.At the same time,the antenna is miniaturized by the bending method.The designed antenna adopts a hybrid feeding method combining microstrip feeding and coupling feeding,and it can work in WLAN(5.725-5.825GHz)and 5G(4.8-5.0GHz)wireless communication system.The dual-band microstrip antenna is modeled and simulated by HFSS.The simulation results show that the antenna has S11<-10 dB,VSWR<2,and input impedance Z11 approximately equals to 50 Ohm in the operating frequency band,achieving good impedance matching;and the antenna has good omnidirectional radiation characteristics.Finally,the miniaturized dual-band microstrip antenna is fabricated,and its reflection coefficient and directional pattern are measured.The test results are in good agreement with the simulation results,which proves the rationality and validity of the antenna design and the correctness of the simulation.