Research And Application Of The Sparse Method For Phased Array Antennas

Phased array antennas have the advantages of beam fast scanning.After decades of rapid development,currently applications of the phased arrays have extended to many fields such as radar systems and wireless communications.With the increasing demand for antenna performance in different fields,the research on phased array antennas is continuously being performed.This thesis has carried out in-depth research on the requirements of large-scale phased arrays for low-cost,wide-angle scanning in the "satcom on the move" systems.This can be divided into two aspects: on one hand,aperiodic array synthesis is used to reduce the number of elements/channels in order to reduce the overall cost of phased array antenna while maintaining its scanning performance.On the other hand,a dual circularly polarized phased array antenna is designed for low-cost and wide-angle scanning performance.The main contents are as follows:1.An improved real number genetic algorithm is introduced as an optimization tool.The preliminary study on thinned and sparse arrays are performed based on linear arrays.Then a hybrid sparse method is proposed for reducing the number of elements in largescale phased arrays while considering engineering practicability.This method combines thinned arrays,sparse arrays and subarrays.An octagonal area array is divided into a number of modular subarrays,and the aperture is sparse in the subarray level,and thinned in the element level.The number of bits of phase shifters in the element level is limited to further reduce costs.In one example,the pattern of the optimized array has no grating lobes in the range of ±60° conical scanning,and the sidelobe levels are less than-16 dB.Compared with a uniform array with the same gain,the number of elements can be reduced by more than a half after employing the proposed method.2.A dual linear polarized wide-angle scanning planar phased array antenna is designed first.An improved patch antenna with coupled feed structure is used to achieve 26% relative bandwidth with VSWR?2.Both vertical and horizontal polarizations can scan to ±60° in the E-plane and the H-plane,respectively.A feed network is added on the basis of the former,and a dual circularly polarized planar phased array antenna is designed with a relative bandwidth of 15%.Both right-handed and left-handed circular polarization can scan to ±60° in the XOZ plane and the YOZ plane,respectively.The axial ratios of the pattern are all less than 3dB within the operating bandwidth.The 8 × 8 and 6 × 6 array prototypes are fabricated for experimental verification.The measured results including VSWR and radiation pattern of the finite array are in good agreement with the simulation results.3.Finally,the above hybrid sparse method is applied to the specific phased array antenna for local verification.The work of sparse post-processing on the simulation and test data of the above-mentioned dual linearly polarized finite array is performed and compared with the theoretical calculation results.It can be seen that the sparse processing has relatively minor impact on the active VSWR of most of ports in the array.The simulation patterns of a finite array are similar to the calculated results.The levels,shapes and positions of the sidelobes are relatively consistent.The patterns of the synthesized octagonal planar array are also consistent with the calculated one.Therefore the effectiveness of the sparse method in this thesis is verified.