Design And Research Of Ultra-wideband Multi-notch MIMO Antenna Based On Fractal Structure

As an important part of sending and receiving electromagnetic signals,the antenna is an indispensable component in the communication transmission system.UWB communication system has the characteristics of high transmission efficiency,wide frequency band and low delay,and its core component UWB antenna has become one of the key research objects of scholars.In the transmission process,the UWB system is affected by the multipath fading problem,and the MIMO technology of multiple input and multiple output can be used to improve the transmission efficiency of the transmission system.Therefore,the combination of the two UWB antennas has attracted extensive attention.There are multiple narrow-band operating bands in UWB systems,and antennas with notch performance can be designed to avoid electromagnetic interference in these bands.Therefore,in view of the design of multinotch and high-isolation UWB MIMO antennas,this paper proposes two ultra-wideband multinotch MIMO antennas based on fractal theory by studying broadband technology,notch technology and decoupling technology.The design of ultra-wideband MIMO antenna with notch function is mainly as follows:1.Design of four-element ultra-wideband MIMO fractal antenna with notch characteristicIn this paper,the "Sierpinski" fractal structure is used to design the antenna unit.After three iterations of fractal,the working bandwidth of the antenna reaches 13 GHz,and then grooves are etched on the microstrip line to eliminate the electromagnetic interference from the X-band."The decoupling structure is used to design a quaternary ultra-wideband MIMO antenna.By simulating the near-field current distribution of the antenna,comparing the model without the fractal structure to verify the feasibility of the decoupling structure,the antenna is finally processed.The actual measurement shows that the size of the antenna is 65 mm×50mm,the working bandwidth is 13 GHz,the working frequency band is 3.1-16 GHz,and the antenna gain is maintained at 6 d Bi.Isolation,the actual measurement shows that the isolation between units is always greater than 15 d B.2.Design of two-element ultra-wideband MIMO fractal antenna with three notches characteristicIn this paper,a two-element ultra-wideband MIMO fractal antenna with a bandwidth of up to 8.6 GHz is designed based on the "Minkowski" fractal structure,and then two "C"-shaped grooves and split-ring resonators in the same direction are etched on the radiating element to ensure that the antenna eliminates three Electromagnetic interference in narrow bands(WIMAX band,WLAN band,X band),and then use a "hybrid" decoupling structure(orthogonal structure and introduction independent branches)to improve isolation,and simulate and compare single decoupling structure and hybrid decoupling The near-field current distribution of the structure verifies that the isolation effect of the hybrid structure is better.Finally,the antenna is processed and tested.The actual measurement shows that the size of the antenna is 50 mm×30 mm,and the working frequency band of the antenna is 2.2-10.8 GHz.The "hybrid" decoupling structure adopted can effectively improve the mutual coupling effect between the units.The actual measurement shows that the isolation between the antenna units is greater than 25 dB,and the antenna radiation Patterns are always omnidirectional...