Circular Polarization Wide Beam Antenna Element And The Array

In communication technology,it is very critical to reduce the transmission loss caused by polarization mismatching and to ensure the polarization matching of the transmitting antenna.In this regard,circular polarization has advantages like that a circularly polarized antenna can receive arbitrary polarization so that it can effectively reduce the influence of multipath reflection and suppress the effect of depolarization caused by rain and fog climate.With the rapid development of wireless communication,the antenna is facing higher requirements such as high gain,narrow beam,low sidelobe and beam scanning,which are difficult to be achieved with only a single antenna.However,these design requirements can be satisfied by the array antenna which is established with a certain combination of antenna elements with optimized excitation coefficients.This thesis focuses on the above analysis,and mainly carries out the following aspects of work through theoretical analysis and simulation:(1)A circular polarized wide beam antenna unit is designed by optimizing the parameters such as the shape of the patch radiator,the feeding position,the thickness of the dielectric plate and the dielectric constant.The half-power beam width,the resonate frequency and the full-plane 3 dB axial ratio are 107.4?,1.58 GHz and 120?,respectively.Since the antenna unit has a simple structure and small size,it is easy to form a group.This model is used to form a phased array antenna and to test whether this model can achieve the desired phased array effect with the CST simulation software.(2)Through the study of mutual coupling between arrayunits,a method of suppressing cross-polarization is found.4?4 array is verified,and a series of studies on its scanning ability and polarization in the main lobe are carried out.After that,a larger array with 64 cells is studied,and,through the phased array technology,the antenna array achieves ?50? scanning range in every plane.(3)After theoretically studying the relationship between the active element patter of the antenna and those of the antenna array,we extract the active element pattem of the antenna from the antenna array.Since we think that the electromagnetic environment around the antenna array element is no longer changed when the size of the array keeps increasing,the far-field pattern of the 20?20 and 50?50 are achieved by Matlab simulations based on the central active element pattern to simulate the scanning performance of a larger array antenna.