| Co-frequency Co-time Full Duplex technology can improve the spectrum efficiency effectively.Comparing to the single antenna system,Co-frequency Co-time transceiver system arrays is faced with more complex multi-dimensional cross coupling strong selfinterference,which puts forward higher requirements and attention for the means and ability of self-interference suppression.This thesis mainly researches the low cost and miniaturization of active phased array antenna on board and the spatial self-interference suppression problem in the scenario of Co-frequency Co-time transmission and reception of the array.The specific research content is as follows:Firstly,a low cost and miniaturized active phase array antenna on board,which is applied in mm-wave communication is designed.In this section,the requirements of active phase array antenna are analyzed,and the related system architecture is proposed.Then analyzing the design indicators of passive arrays and active transceiver components,respectively.At last,the active phase array antenna with complicated technique is designed and implemented on an 18-layer printed circuit board.Furthermore,the proposed active phase array antenna has two transmitting arrays and two receiving arrays,which can support beam scanning in the ±45° range.In addition,each array contains 256 elements.Secondly,passive and active spatial self-interference suppression methods are proposed for the Co-frequency Co-time receiving and transmitting circumstance of arrays.Passive suppression method uses a hexagonal electromagnetic bandgap structure for suppressing the surface waves excited by coplanar antennas.By simulating the scaled model of an active phased array,the results show that the proposed structure can effectively reduce the coupling between the transmit and receive arrays.The active suppression changes the weight of transmit beamforming,reducing the self-interference power received by the receiving array while the transmission gain degradation is minimum.A mathematical model for self-interference optimization is established and zero space mapping principle and maximum self-interference power constrained methods are used for optimization.Simulation results verify that the zero space mapping principle optimization method can suppress the self-interference signal by 32 dB at a gain loss of1.2dB,while the constrained optimization method can suppress the self-interference signal by 25 dB at a gain loss of 1dB.Thirdly,an active phased array test platform is built and self-interference suppression experimental tests are completed on it.The test results illustrate that the equivalent omnidirectional radiation power of the active phased array exceeds 54 dBm,and the directional pattern is good.In addition,using passive suppression methods can exhibit isolation levels of 104.5dB,93.2dB,and 109.1dB in microwave anechoic rooms,indoor office environments,and outdoor open environments,respectively.Moreover,in a microwave anechoic room,using zero space mapping optimization and maximum receiving power constraint optimization can improve the transmit and receive isolation of10.5dB and 19.4dB at the expense of 1.2dB and 1.6dB antenna gain on the basis of passive suppression.The maximum isolation of the transmit and receive array can up to about123 dB.Eventually,the feasibility of applying the active phased array system to full duplex communication is proved through full duplex communication experiments.The research in this thesis provides a design scheme for a miniaturized mm-wave base station antenna,and provides a solution to the problem of spatial self-interference suppression in Co-frequency Co-time Full Duplex array systems. |
