Research On Microwave Wideband Passive Devices And Spoof Surface Plasmon Polaritons

Recently,as the wireless technology develops faster and faster,it is highly necessary to increase the communication capacity to satisfy the high-speed communication needs.Such situation calls for much more stringent requirement on the electromagnetic(EM)devices.Microwave wideband passive devices have become one of the hot topics in EM community as well as the spoof surface plasmon polaritons.In this thesis,a series of microwave wideband passive devices were proposed to satisfy the engineering and academic needs,such as ultra-wideband(UWB)notched-band power divider,wideband notched-band filter,UWB antenna,etc.In the meanwhile,based on the conception of the spoof surface plasmon polaritons(SSPP),it is the first time to propose the differential SSPP waveguide design and the coplanar stripline(CPS)-based SSPP design.In addition,a fish-bones SSPP structure is also presented,which can achieve stronger confinement to the SSPP propagation.This thesis topics include as follows,Firstly,in the second chapter,a UWB Wilkinson power divider with tunable notched band is presented.The odd-even mode theory is used to analyze the three stubs loaded resonator for notched band,which is then embedded into the UWB power divider.The center frequency of the notched band can be tuned by changing the physical dimensions which is an angle index.Thus,a UWB power divider with tunable notched band is created.The measurement results show that the return loss in passband(i.e.,0.1-8GHz)is better than-10 dB.Besides the notched band,the isolation between two output ports are higher than 18 dB.In the third chapter,a novel monopole UWB antenna based on microstrip feedline is proposed.To suppress other noise in UWB range,two notched bands with high frequency selectivity is designed.In each notched band,two resonant modes are provided when compared with traditional notched band with only one resonant mode.The designed notched bands are suitable for suppressing wideband noise,such as 4G communication.Such notched bands are created by adopting the proposed novel.In this chapter,parametric study is carried out for the proposed UWB notched band antenna explaining the operation mechanism of the proposed structure.Finally,the return losses,radiation pattern and the peak gains of the proposed antenna is obtained,which verifying good impedance matching performance and radiation characteristics of the presented antenna.Additionally,a multi-state UWB antenna is presented which can realize simple and quick conversion between two operation states: narrow bandwidth bandpass filtering response(passband: 5.5-5.95 GHz),UWB response with notched band(passband: 3.1-11.5 GHz,notched band: 5.15-5.8 GHz).The notched band has high frequency selectivity.And the 0 ? resistor is adopted to replace the loading shunt stubs,which is also studied.Four antenna prototypes are fabricated and measured to validate the multi-state UWB antenna.In the fourth chapter,a novel UWB filter with two notched bands is proposed.The dual notched bands feature is evoked by using the proposed resonator in the third chapter.Thus,in each notched band,two resonant modes are included improving the bandwidth of the notched band.The notched band also has high frequency selectivity.Based on the analysis in the third chapter,in this chapter,more data is collected and analyzed by the full-wave simulation and an equivalent model for the notched band resonator is proposed for future design of the resonator.In order to obtain wider out-of-band suppression,defect ground structure is applied in this design.In the fifth chapter,a novel fish-bones SSPP waveguide structure operating in microwave regime is proposed.Compared with existing traditional structure,such design can achieve lower dispersion curve implying stronger confinement for the SSPP propagation.The simulation research and measurement results show that this structure can obtain wideband bandpass response.This is because the cutoff frequency characteristics of the dispersion curve generate high-frequency stopband,while the microstrip-slotline transition created the low-frequency stopband.Therefore.two stopbands help to create the wideband response.To validate the proposed structure,full-wave simulation is carried out demonstrating the dispersion feature,current distribution,and energy flow distribution.In addition,it is first time to propose the THz SSPP design developed from the coplanar stripline(CPS)while the previous design is based on the microstrip or the slotline.And to reject the common-mode interference,a differential SSPP with high common mode rejection is proposed for the first time.Finally,a summarization about this thesis is provided.