Research On Dual-band Dual-polarization Microstrip Filter Antenna

Antenna and filter play a very important role in the RF front-end of wireless communication system.The research on the integration of filter antenna can not only greatly reduce the size of RF front-end,but also avoid the insertion loss caused by matching network in traditional design methods.On the other hand,with the rapid development of wireless communication technology,more and more user groups also put forward higher requirements for antenna performance.Single frequency band antenna with single function can not meet the requirements,and multi-frequency antenna has been widely used.In order to reduce the mutual interference between each working frequency band of the antenna,different radiation frequency bands often adopt different polarization methods.For example,Antennas working in GPS band generally have circular polarization characteristics,while antennas working in Wi-Fi bands and GSM bands mostly adopt linear polarization.In this context,it is necessary to design an antenna that can meet the characteristics of multi-band and multi-polarization.This thesis mainly studies and designs the dual band dual polarization micro-strip filter antenna.The research work is mainly divided into the following parts:1.A dual-band dual-polarization filter antenna array is proposed.Based on the current distribution law of the terminal open circuit micro-strip line and the coupling feeding mode,rectangular patches are periodically arranged in the longitudinal direction of the micro-strip line to form a micros-trip antenna array.By choosing the appropriate patch size and coupling region,the radiation of specific frequency band and high out of band suppression can be realized.Two patches of different sizes are staggered to form a dual frequency antenna array.Due to the orthogonal direction of the coupling current,the polarization directions of the two frequency bands are also perpendicular to each other,which has a very high degree of polarization isolation.In addition,the CSRR structure is etched on the low-frequency patch to realize harmonic suppression and reduce the interference of high-order harmonics of low-frequency patch to high-frequency patch.The working frequency bands of the antenna array are 2.49 GHz-2.52 GHz and 4.84 GHz-4.92 GHz,and the maximum gain is more than 12d Bi.The antenna is processed.The S-parameters and pattern of the antenna are tested in the darkroom environment.The test results are almost consistent with the simulation results,which verify the effectiveness of the antenna design.2.A dual-layer dual-band dual-polarization filter antenna is proposed.The antenna completes the radiation of two frequency bands of 3.13 GHz-3.17 GHz and 5.73 GHz-5.87 GHz respectively by using two layers of patches.The polarization directions of the two frequency bands are perpendicular to each other.The coaxial probe is used to feed the high-frequency patch and the micro-strip line is used to feed the low-frequency patch.The dual polarization characteristic is realized by adjusting the feed structure.The CMRC low-pass filter structure is loaded on the micro-strip line to filter the second harmonic of the low-frequency patch,and the slot is etched on the high-frequency patch and the radiation zero point is introduced to improve the roll off degree of S₁₁ curve in the high-frequency band of the antenna.