Design Of Coupled Feed Microstrip Antenna Array

In recent years,coupled feed microstrip array antenna is a hot research direction.The antenna array is fed by electromagnetic coupling,which can not only broaden the antenna bandwidth effectively,but also can improve the freedom and flexibility of the array design which make the design of radiation part and feeder optimal.In addition,as a new type of guided wave structure,substrate integrated waveguide plays an important role in the array antenna.Based on the new trend of the development of coupled feed microstrip antenna array and combining the actual demand of the project,this thesis studies and designs two kinds of microstrip array antenna for wireless communication system and automobile anti-collision system,respectively.The main contents of this thesis are as follows:1.An 8-channel receiving microstrip patch antenna array is designed,which can be used in the MIMO system.Each receiving antenna is a 1×3 array made of microstrip patch antenna,and the 8 antennas corresponding to the 8 receiving channels are arranged in the equal distance.First,a broadband microstrip patch cell is designed by reducing the equivalent circuit Q value and using slot coupled feed broadband technology.Then,the three-way equal divider is designed by parallel feed mode,and the traditional microstrip transmission lines are used to achieve equal amplitude and in phase feeding.In the working frequency band of 5.25GHz?5.8GHz,the VSWR of each receiving antenna is below 2,and the gain is above lO.OdB.The MIMO received array antenna has a compact structure.The coupling effect between channels is small,and the isolation between them is above 15dB.The MIMO received array antenna has a good channel consistency,and it is competent for the wireless communication system.2.Design of a 4×10 microstrip array antenna fed by the combination of microstrip transmission line and SIW coupled slot is presented.The antenna array has a shaped beam pattern.In the one-dimensional antenna array design located in the azimuth plane,the edge-fed microstrip rectangular patch is selected as the antenna element,and the amplitude distribution of the array element is obtained by Chebyshev synthesis to meet the requirement of the sidelobe level.Series feed design is adopted to reduce the loss of feeder.The feed amplitude distribution and impedance matching of the 5-element series fed microstrip array on single side are realized by combining the tapered microstrip gradient line with the conventional microstrip transmission line.On this basis,the differential evolution algorithm is used to form the shaped beam in the elevation plane,and the feed amplitude and phase distribution of the 4-element sub array are obtained.In order to realize the shaped beam in the elevation plane,the feed network based on SIW is adopted to realize the current distribution with unequal amplitudes and different phases.The feed network is composed of SIW-slot-microstrip coupling structure,SIW power divider,SIW phase shifter and cone-shaped SIW-microstrip line converter.By optimizing the structural parameters of each part in the feed network,it can achieve the excitation requirement of shaped beam.Eventually,the maximum radiation in the elevation plane is pointing to about ?=30°,and the gain is more than 14dB with the sidelobe level below-9dB.The measured results show that the array antenna has good radiation performance and can be applied to the vehicle collision avoidance radar system.