Research Of Self-Packaged Directional Couplers Using Broadside-Coupled Suspended Coplanar Waveguides

With the rapid development of modern wireless communication system,the circuit system is required not only to achieve miniaturization but also to be highly integrated.The traditional planar circuit has been unable to meet the design requirements of scientific research workers,and the excellent three-dimensional circuit has been paid more and more attention.Multilayer suspended circuit has been widely used in the design of various RF devices.However,its development is limited by its large circuit size,heavy weight and difficulty in production.In order to overcome these defects,it is necessary to introduce new transmission line technology to improve the performance of the circuit.At the same time,communication systems tend to be more stricter about microwave devices.Moreover,high-performance microwave devices integrating multiple functions can also simplify circuits.Thus,the integrated design and high-performance research of microwave devices has always been a research hotspot.Directional coupler as one of the key components of RF and microwave circuit,and it can realize phase difference,power distribution,power synthesis and other important functions in the output port.Moreover,it plays an important role in the system.Therefore,the research of integrated and high performance directional coupler has important scientific significance for the development of wireless communication system.In this thesis,based on the novel transmission line structure of Broadside Coupled Suspended Coplanar Waveguide proposed for the first time,and using the comprehensive theory of Broadside Coupled Coplanar Waveguide,the research work is carried out in such important development directions as miniaturization,high performance,integrated design and wide band of directional couplers.Firstly,the design theory of broadside coupled coplanar waveguide which is not mature enough is integrated and verified by calculation.The complicated theoretical calculation formula is converted into Matlab program to assist the design and calculation,which greatly reduces the design workload and simplifies the design process.Secondly,a novel Broadside Coupled Suspended Coplanar Waveguide is proposed for the first time.The transmission line can guarantee superior transmission performance up to 17GHz.With the use of ordinary PCB manufacturing technology,the circuit can achieve the advantages of low loss,low cost and self-packaged.Meanwhile,Taking advantage of the space advantage of multilayer structure,the design method of double-sided circuit is proposed.Thirdly,the design method of 3dB coupling line directional coupler is proposed by using the BC SCPW.The directivity of the coupler is improved by using the method of U-shaped line coupling and grounding short transversal.Compared with the existing results,it has the advantages of miniaturization,high directivity,low loss and self-packaged.Fourthly,the electromagnetic shunt coupling resonator is introduced into the input port extension section of the single 3dB coupling line coupler on different surfaces by using the method of double-sided circuit.And the integrated design of band-pass filtering and power distribution is realized.Meanwhile,the source-load coupling structure is used to ensure that both sides of the passband have controllable transmission zeros,which improves the out-of-band suppression ability of the band-pass filter coupler.Lastly,on the basis of the research of the 3dB coupling line coupler,a two-port broadside coupling line with band-pass response is proposed in its four-port extension section.Meanwhile,the wide band matching condition of the wide band coupler is used to make the four ports meet the matching condition simultaneously.The design of a wideband filter coupler with a relative bandwidth of 73.3%is realized.