| The miniaturized ultra-wideband MIMO antenna combines ultra-wideband technology with MIMO antenna technology and antenna miniaturization technology,so that it has the advantages of ultra-wideband communication technology such as high transmission capacity,high speed and low power consumption,but also has the advantages of MIMO communication technology such as high transmission reliability and solving multipath effect,therefore,this technology has been a hot spot for domestic and international research.In order to avoid interference between the miniaturised ultrawideband MIMO antenna and other frequency bands,it is also important to study the miniaturised ultra-wideband MIMO antenna with wave trapping function.However,a fixed structure of a miniaturised UWB MIMO antenna capable of filtering a given frequency band is not flexible enough to cope with the various situations that may arise in practice.Therefore,the following work has been done to combine UWB technology and MIMO technology while miniaturising the antenna and reconfiguring the trap frequency.Firstly,a combination of miniaturisation,trap frequency reconfiguration and ultrawideband antenna technology was developed to achieve a coupling of less than-15 d B in the ultra-wideband range and less than-20 d B in the 7GHz-11 GHz range.By etching Lslots and U-slots on the antenna surface,the antenna has trap characteristics in the5.1GHz-6GHz and 7.2GHz-9GHz bands.Finally,the antenna has four operating states by adding an ideal switch at the trap structure.Secondly,a miniaturised ultra-wideband MIMO antenna with trap frequency reconfigurable function using PIN diodes is investigated in order to achieve on-demand switching of the trap band in a trap frequency reconfigurable ultra-wideband MIMO antenna controlled by an RF switch.Firstly,the coupling of a MIMO antenna composed of a monopole antenna is reduced by using a T-shaped floor branch;secondly,the antenna is given 3.0GHz-4.2GHz and 4.8GHz-5.9GHz trap bands by etching a CSSR ring on the antenna radiation patch and a rectangular thin slot on the floor,and then a PIN diode and a corresponding biasing circuit are added at the appropriate position of the trap structure to control the switching of the antenna operating mode using The PIN diode controls the switching of the antenna operating mode.Finally,a miniaturised four-port UWB MIMO antenna with PIN diode switching is designed in order to investigate the application of trap reconfigurability and antenna miniaturisation techniques to UWB MIMO antennas with a large number of ports.A miniaturized ultra-wideband monopole antenna is firstly obtained by the half-cut method,and then the four unit antennas are placed orthogonally to reduce the coupling,and the antenna is etched with fine slots on the radiation patch to achieve the trap characteristics at 4.9GHz-6.2GHz and 3.1GHz-4.1GHz.Finally,the four operating states of the antenna are implemented and switched by loading the trap structure with a PIN diode and its biasing circuit. |
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