Research On New Type Microwave Patch Antenna

The antenna is one of the core components of the wireless communication system,and its performance largely determines the performance of the whole communication system.With the development of modern communication systems,many communication devices are becoming smaller and more integrated.Because the patch antenna has many advantages such as low profile,easy conformity,its working performance is not easily influenced by the rest of the components of the communication device,easy integration with the active circuit,and easy realization of circular polarization,it is widely used at microwave band.However,the gain of traditional patch antenna is low and traditional patch antenna can only achieve horizontal polarization,which greatly restricts the application of the traditional patch antenna in the current communication system.This thesis designs a magnetic dipole patch antenna which can realize the vertical polarization,and introduces the metarmaterials into antenna design to improve the gain of the patch antenna.On the other hand,base stations of wireless communication systems,including antennas,are installed on high-rise buildings and communication towers,this leads to the main beam of antenna need to be tilted at an angle.Therefore,two beam tilting antennas are designed in this thesis.The main achievements of this thesis are:1.When the traditional planar I-shaped resonator and the vertically polarized antenna are integrated into the same substrate,the I-shaped resonator cannot be excited.In order to slove this problem,a vertical I-shaped resonator with a 3D structure is proposed.The periodic arrangement of the vertical I-shaped resonators can constitute a single negative(SNG)metamaterials.The metamaterials has a higher refractive index when the frequency is lower than the resonant frequency,and the S-parameter extraction method is used to obtain the electromagnetic parameters of designed metamaterials.2.According to the traditional Yagi antenna and metamaterials,a magnetic dipole Yagi antenna I based on metamaterials is designed.The antenna consists of a director,an reflector,and a magnetic dipole antenna.The final simulation results show that the gain of the antenna has been significantly improved and vertical polarization is achieved.According to the experience of the traditional Yagi antenna,it can be seen that the gain of antenna would increase as the number of directors increased.In order to further improve the gain of the antenna,a magnetic dipole Yagi antenna II based on metamaterial is designed.Different form the Yagi antenna I,Yagi antenna II has four directors.The Yagi antenna I and the Yagi antenna II were finally processed and tested.The test and simulation results are in good agreement,which further illustrate realizability of the design.3.According to magnetic dipole antenna and metamaterials,a beam tilting antenna based on metamaterials is designed.Simulation results show that the main beam of the antenna in H-plane is tilted by 17? and the gain of the antenna is also improved.In order to further improve the tilt angle of antenna,a beam tilting antenna based on gradient refractive-index media is designed.Simulation results show that the main beam of the antenna in H-plane is tilted by 23?.