Research On Single Radiator MIMO Antennas

The problem of designing a tightly coupled MIMO antenna in a limited volume is to eliminate the correlation.The research results related to its solution are employing de-correlation spatial structure,de-correlation network structure,polarization diversity and pattern diversity.The traditional method is to design a tightly coupled multi-antenna firstly and then perform de-correlation processing.In this paper,the design method is to solve the problem of port isolation first.A two-port single-radiator MIMO antenna model with port isolation is established according to a two-port passive circuit model with port isolation characteristics,then discuss and verify the decoupling effect and radiation ability,finally design the port matching through by loading a matching network or adjusting the antenna size parameters.This method can solve the de-correlation problem of MIMO antenna more easily and systematically.Based on this method,two simple basic topology——line type and ring type with port isolation are proposed.In this paper,two types of single radiator MIMO antenna models are designed by this method,and the corresponding dual frequency antenna is designed respectively.The main contents of this article are as follows:First part: A linear single-radiator MIMO antenna is designed.Firstly,a simple passive circuit model with port isolation feature is proposed by analyzing the scattering parameters.The dual-port linear circuit is used to verify and analyze the relevant parameters of the isolation characteristic in ADS.Then,a dual-port single-radiator MIMO antenna is designed according to the circuit model.The relationship between the structural parameters and the performance of the antenna is simulated and verified in HFSS.Finally,the parameters are optimized for the good matching and as small as possible size according to the relationship between the structural parameters and performance.Second part: Two ring single radiator MIMO antennas are designed,respectively,to load matching networks and do not load matching networks.Firstly,the condition of port isolation is obtained based on Y parameter analysis,and the simulation is verified in ADS.Then,the MIMO antenna model with port isolation and radiation characteristics is designed according to the port isolation condition.Finally,we use the method of loading matching network and adjusting antenna parameters to achieve antenna port matching.And the coupling factor and the radiation efficiency are used to analyze the different effects of the matching network under the two kinds of size parameters,which leads to a key problem that the antenna design method needs to pay attention to.Third part: A linear and a ring dual-band single-radiator MIMO antennas are designed respectively.The linear and ring basic structures are made a dual frequency expansion respectively.The first step is to design a linear and ring passive circuit model with dual band isolation characteristics,and then design the corresponding dual-frequency single-radiator MIMO antenna according to the circuit models.