| To meet the growing demand for high-quality communication,the fifth-generation mobile communication technology has been developed by many countries.Millimeter wave communication technology,as an important part of 5G technology,is getting increasing attention and has been employed in many areas.The research on millimeter wave antenna has been fully carried out,among which millimeter wave microstrip phased array is one of the most popular applications.In addition,Continuous Transverse Stub(CTS)antenna,which is a new type of antenna,has become a research point because of its excellent radiation performance.In this article,the scanning blindness in millimeter wave microstrip phased arrays and multi-beam CTS array antennas are studied,and the main works are as follows:A stripline aperture coupled microstrip antenna array operating at 26.5GHz～29.5GHz was designed,and the scanning blindness in the antenna is analyzed.Due to the presence of surface waves in the substrate,the active reflections of antenna cells are enhanced.In some angles the antenna cells behave as total reflection,the antenna can not radiate energy outside,resulting in a scanning blindness.The scanning blindness prediction method is also studied in the paper,and the two-port transmission model is employed to predict the scanning blindness.Scanning blindness suppression methods are designed according to the causes of the problem.The first kind of methods use electromagnetic band-gap structure(EBG)and defect grounded structure(DGS)to suppress surface waves,including Unplanar Compact EBG(UC-EBG)and Slotted Complementary Split-Ring(SCSRR).The second kind of method suppress the scanning blindness by optimizing the feeding structure,including periodically placing metal vias in the feeding layer,using microstrip line aperture coupled feeding and using microstrip line adjacent coupled feeding,and all three methods have achieved good results.A multi-beam SIW-based CTS array antenna operating in the millimeter wave band was designed.The antenna achieves multi-beam capability by switching the feeding port.The structure of the antenna is simple and can be realized using PCB technology.The antenna consists of three main components(feeding horns,plane wave conversion structure and radiation part)and is composed of three layers of substrates.The primary feed source are SIW feeding horns,with matching structure added at the aperture to improve the radiation performance.The plane wave conversion structure consists of SIW parabolic surface and gradient coupling slot,which can convert the column wave radiated from the feeding horns into plane wave with the amplitude obeying Taylor distribution to feed the CTS array,so the antenna has the characteristics of low sidelobe.The radiating part is an 1×8 CTS array,and the stub width is optimized to ensure that each element radiates the equal amount of energy.The antenna works at 30 GHz,and can achieve beam switching in the range of ±20° by changing the feeding port.The antenna measurement results agree well with the simulation results,which verifies the reasonability of the design. |
