Design And Research Of Novel Wideband MIMO Antennas

With the development of social economy and culture,all kinds of multimedia services are emerging,and the requirement of wireless communication system is increasing.In the communication system capacity,transmission rate and so put forward new requirements.The use of multi-antenna systems,especially the use of multiple-input multiple-output(MIMO)systems,is an effective way to increase channel capacity,speed up transmission rates and enhance reliability within a limited bandwidth.However,setting multiple antenna elements in a smaller space will cause the coupling between the antenna elements to stimulate the coupling surface current,thus affecting the overall performance of the antenna.How to enhance the isolation to become the core of MIMO antenna technology development.And how to maintain good isolation between the antenna elements of the MIMO antenna in the broadband range is also an important research direction.The main contents of this paper are as follows:1.A 4 × 4 wideband high-isolation MIMO antenna is designed with a working frequency of 4.3-15.5GHz.Based on the principle of stub loading,with good isolation,the isolation in the working bandwidth of more than 15 dB,in most of the bandwidth of more than 20 dB.The antenna size of 40 × 40mm~2,using FR4 dielectric substrate,the relative dielectric constant of 4.4,the thickness of 0.8mm.The antenna unit is designed as a coplanar waveguide antenna,the ground itself can produce a similar role with the traditional ground stubs,change the coupling current distribution,and enhance the isolation between ports.And by further designing the relative position of the antenna elements,the effect of further reducing the coupling is realized.2.A compact multiple-input-multiple-output(MIMO)antenna with a small size of 25×40×1.6mm~3 is proposed.The two antenna elements with microstrip-fed printed on the substrate and placed symmetrically to operate at 5.8 GHz.The reduction of mutual coupling between the two antenna elements is achieved by using metamaterials structure,placed in the space between the antenna elements to provide an effective means of limiting the surface waves between them.The designed antenna elements have better than-24 dB coupling isolation between the two inputs and required good radiation pattern,efficiency and gain.3.A planar monopole miniaturized UWB MIMO antenna is designed.The antenna introduces the ground stub between the two planar monopole antenna elements,optimizing the impedance matching bandwidth and improving the isolation of the antenna by optimizing the parameters of the ground stub.The miniaturized MIMO antenna operating frequency band is 3-10.7GHz,the size is only 30 × 40mm~2,suitable for ultrawideband wireless communication system.