Multiband Directional Antenna And Diplexers Design

The era of 5G is approaching,mobile communications are rapidly developing,and the construction of a new mobile communications network is in full swing.The outdoor coverage of mobile communications has gradually improved,but in areas where buildings and people are crowded,the coverage area,signal capacity,and communication quality of signals cannot be guaranteed.Outdoor mobile communication base stations cannot meet people's requirements.Therefore,there are still many aspects of indoor mobile communications that need further improvement.The indoor distribution system is mainly used to solve the indoor communication problem,and the role of the indoor distributed antenna is to evenly distribute the signals of the mobile base station indoors,thereby solving the indoor signal coverage problem.Therefore,the indoor distributed antenna is an important part of the indoor distribution system.The performance of the indoor antenna plays a decisive role in the merits of the indoor distributed system.Therefore,research on indoor distributed antennas is of great significance.In this paper,the multiband dual-polarized antenna and diplexers used in the indoor distribution system are studied.The main results of the research are as follows:According to different theories,three dual-polarized antennas are designed to work in different frequency bands.According to the basic theory of dipole antenna and type III microstrip balun feeding,a±45°dual-polarized antenna working at the frequency of 880MHz-960MHz is designed;Based on the basic theory of dipole antenna and type III coaxial balun feeding,a±45°dual-polarized antenna working at 1710MHz-2690MHz was designed;according to the differential feeding theory and patch antenna theory,a±45°dual-polarized antenna working at 3400MHz-3600MHz was designed.The main parameters that affect the performance of the antenna were simulated and analyzed.The antenna structure was optimized.The antenna was processed and measured according to the antenna's simulation results.The measured parameters included the antenna's S-parameter,direction pattern,and cross-polarization direction,gain,etc.The measurement results are basically consistent with the simulation results.Low-frequency antenna in the 880MHz-960MHz obtains|S₁₁|<-15dB,gain more than 8.3dB;Medium-frequency antenna in the 1710MHz-2690MHz obtains|S₁₁|<-12dB,gain more than 7.4dB;high frequency in the 3400MHz-3600MHz obtains|S11|<-10dB,gain more than 7.8dB.The antennas all have good beam width,front-to-back ratio,and cross-polarization ratio.In order to avoid space waste and reduce the number of cables and systems,according to the basic theory of the filter and microstrip line design method,a three-way combination road is designed to work in the range of 880MHz-960MHz,1710MHz-2690MHz,and 3400MHz-3600MHz.The design idea of the diplexers is introduced and processed and measured.The diplexers has a good S-parameter and can be applied in an indoor distribution system.