Slow-Wave Structure Based Miniaturized Rotman Lens And Its Application In Multibeam Antennas

Rotman lens is a planar beamforming network commonly used in passive multi-beam antennas,which has the advantages of stable beam pointing,easily wide Angle coverage and simple structure.Rotman Lens designed by substrate integrated waveguide has advantages of low cost,low profile,and easily integrated with other planar circuits compared with metal waveguide lens.Although the substrate integrated waveguide rotman lens has better performance in microwave and millimeter wave band compared with the microstrip rotman lens due to its low radiation loss and low insertion loss,its size is larger.Miniaturized microwave components can be designed by loading slow wave structure into the components to reduce the phase velocity and the guided wave length.In this thesis,a miniaturized rotman lens based on slow wave SIW is designed,and two multi-beam antennas with different antenna elements are designed based on the miniaturized Rotman lens.Aiming at the research of slow-wave substrate integrated waveguide rotman lens and its application in multi-beam antenna,the following work are carried out in this thesis:1.A miniaturized slow-wave substrate integrated waveguide Rotman lens is designed.The miniaturized Rotman lens is designed by loading slow-wave structure inside the Rotman lens to improve the dielectric constant of the substrate integrated waveguide and reduce guided wave length.Same electrical size as that of the normal SIW Rotman lens is realized with a smaller physical size.Compared the rotman lens without slow-wave structure,the area of the lens is reduced by 66.2%.By adjusting the arrangement of the metalized blind holes of the slow-wave transmission line,the transmission lines with different slow wave coefficients are designed to adjust the phase of different output ports of the Rotman lens respectively.Finally,the miniaturized slow-wave substrate integrated waveguide rotman lens have good amplitude and phase output characteristics in 15.3GHz-16.3GHz.2.Two types of multi-beam antennas based on slow-wave substrate integrated waveguide Rotman lens are designed.Based on the miniaturized slow-wave substrate integrated waveguide Rotman lens,multi-beam antennas based on Vivaldi antenna and dipole antenna are designed.The multi-beam antenna based on printed dipole antenna is selected for processing because of it has better polarization purity than the multi-beam antenna based on Vivaldi antenna.At the central frequency of 15.8GHz,measurements showed the beam direction are-34.2°,-17.4°,0°,17.8° and 35.5° respectively,and the gains are 4.29 d Bi,6.46 d Bi,8.06 d Bi,6.65 d Bi and 4.82 d Bi respectively.The measurements are in good agreement with the simulations,which verifies the feasibility of multi-beam antennas based on miniaturized slow-wave substrate integrated waveguide rotman lens.