Study On Microwave Passive Component And Antenna Based On 3D Printing

With the arrival of the Fourth Industrial Revolution,the rapid development of emerging technologies has raised higher demands on wireless communication systems.This has led to a more complex electromagnetic environment for wireless communication systems,as the rapid development of wireless communication technology.These technologies require high-performance microwave,millimeter-wave,and terahertz devices as hardware support,making the performance requirements for microwave devices more stringent.Therefore,microwave devices are evolving towards miniaturization and multifunctionality.Compared to planar microwave transmission lines,waveguide components have the advantages of low loss,high power capacity,and suitability for high-frequency applications.However,waveguide components with excellent RF performance often come with complex geometric structures.Microwave components are often subject to the limitations of the conventional manufacturing processes,and some components with complex geometric structures are difficult to produce.Therefore,for components manufactured by conventional processes,engineers must design devices with more consideration for manufacturability,and thus have to make sacrifices in terms of device performance.In recent years,the emerging 3D printing technology has been widely used to manufacture high-performance,lightweight microwave components and subsystems.This technology enables the rapid and cost-effective production of complex three-dimensional geometries,which provides designers with great design freedom and reduces the constraints imposed by considerations of device manufacturability.This allows designers to break free from the limitations of traditional structures and design novel high-performance devices.This dissertation focuses on high performance,multifunctional microwave waveguide passive components and antenna for communication systems using the design freedom provided by 3D printing technology.The main research work is summarized as follows::1.A filter based on rotary coupling structure is proposed.By changing the angle between resonators,the coupling strength of the filter is controlled instead of the conventional iris.The filter only consists of resonators and input/output waveguides.This filter is less sensitive to dimensional errors than the iris-coupled filters since slight deviations in volume during 3D printing do not lead to variations in rotation angle.The most distinctive feature of this filter is that,due to the simple filter structure,coupling can exist between non-adjacent cavities without the use of additional cross-coupling structures,which can generate transmission zeros near the filter passband.By changing the direction of the adjacent resonator rotation angle,the transmission zeros can be generated at lower and/or upper stopbands.2.A novel filtering twist is proposed based on the cooperative design method.Two types of 3D printed filtering twist that integrate frequency selectivity of filter and polarization rotation of twist are designed using twisted resonators or rotating adjacent resonators at a certain angle.The filtering twist with a rotating outer shape can be easily manufactured using 3D printing technology.Compared with the traditional cascaded structure,the filtering twist has the advantage of compact size.It also reduces the lead time and cost associated with post-assembly and further minimizes the volume.In addition,to enable the new filtering twist to be manufactured with CNC machining process,rotational deformed resonators is utilezed to construct the filtering twist,making it compatible with mature CNC machining processes.And a filtering twist that can be manufactured using CNC machining is designed.3.A high-gain filtering antenna based on a horn antenna is proposed.This new type of filtering horn antenna can simultaneously achieve high gain,circular polarization,and filtering response.First,a filtering mode transformer is used to split the TE₁₀ mode input from the 45 degree oblique port into two orthogonal modes with equal amplitudes,while also achieving a filtering response.Then,a phase shifting structure is embedded in the horn of the filtering antenna to achieve phase shift.This can result in a 90 degree phase difference between the two modes and produce circularly polarized waves.Unlike traditional metal horn antennas,this antenna uses non-metallic materials with much lower density as the structural material for this antenna.With metallization of the device surface at a later stage,it is possible to achieve the same RF performance as an all-metal device,but with a significant weight reduction.This is critical for the lightweighting of radio communication systems,especially satellite and aerospace communication systems..4.The study of filters with high unloaded Q in the existing literature is extended to the study of multifunctional filter with high unloaded Q.Two filtering interconnect components integrated with both bend and twist functionality were designed.Both of these interconnect components can achieve complex waveguide routing,as well as polarization rotation and filtering response.The employment of elliptical and spherical resonators enables both filtering interconnect components to have low-loss characteristics.During the device design process,traditional spherical resonators used for constructing high unloaded Q factor filters have high symmetry and are not suitable for constructing filters with polarization rotation.Therefore,the spherical resonators were modified and deformed to maintain the high unloaded Q factor characteristic while being suitable for designing filters with polarization rotation.Finally,using spherical and spheroidal resonators,multiple low-loss filtering crossovers were designed to meet the needs of cross transmission in current complex circuits.