The Propagation Characteristics Of Three Kinds Of Microwave Periodical Waveguide Stuctures

Three kinds of periodical structure are studied in this dissertation including the substrate integrated waveguide?SIW?,leaky-wave antenna?LWA?and the left-handed couple line.The generalized scattering matrix based on the finite element method?GSM/FEM?is the numerical method to extract the propagation constants of the three structures.The dissertation begins with the influence of the structural parameters on the SIW propagation constants.Then two complex mode regions in different frequency ranges caused by the energy leakage phenomenon can be observed from the scattering curves.The space harmonic coupling causing the leakage phenomenon is studied and it can be concluded the space harmonic coupling is related to the ratio of the gap between two vias in the SIW structure and the diameter of the vias after discussing the forming condition of the space harmonic coupling Furthermore,three-dimensional electromagnetic field analyses in the complex mode frequency ranges on ANSYS HFSS^TM software are implemented to validate the leakage phenomenon.A new SIW structure based on the CMOS 130nm 1P8M foundry process is proposed in this paper and a simplification method for extracting the propagation constants is proposed and used to reduce the time cost of the calculation.In addition,the GSM/FEM numerical method is also used to extract the modes in the leaky-mode microstrip and the leaky-wave antenna.The left-handed modes are discovered in the microstrip and the coupling between left-handed modes and higher order modes existed in the microstrip are observed.PMC?Perfect Magnetic Conductor?boundary and PEC?Perfect Electric Conductor?boundary are respectively implemented in the middle of the leaky-mode to purify the modes in the microstrip.This dissertation also presents a novel leaky wave antenna loaded by periodical open stubs and holes.The complex propagation constants of the first higher order mode of the periodically loaded microstrip,so-called the EH₁ mode,are extracted by the field eigenvalue approach,leading to control the radiation characteristics by changing the loading conditions.By doubling the length of open stub,the operating frequency of the LWA can be shifted 8.9%toward to the lower frequency.The comparison of the dispersion curves between the loaded and conventional microstrips shows 20%width reduction on synthesizing the EH₁ mode.Two 9 GHz and 10 GHz practical prototypes are designed based on the proposed methodology and fabricated by using the multilayer printed circuit board?PCB?technology.The measured return-losses of two LWA prototypes are lower than 10 dB.The measured antenna gains of two LWA are 5.37 dBi and 6.89 dBi.The maximum gains are 6.05 dBi and7.43 dBi at 9.2 and 10.1 GHz.The beam scanning angles are 7 degrees and 4 degrees when the frequency is increased 0.2 GHz.Lastly,the symmetric composite right/left-handed coupled-line model is proposed to extract the scattering curves of the c mode and?mode in the structure.Due to the fact that the coupling coefficient is related to the phase difference between c mode and?mode,several left-handed couplers with different capacitor fingers and the length of the inductance are simulated to achieve large phase difference.It can be concluded after the simulation that less capacitor fingers and longer shunt inductance can bring larger phase difference.A left-handed coupled-line forward coupler based on standard0.13 nm CMOS 1P8M foundry process is fabricated.The center frequency of the coupler is 390 GHz and the bandwidth is 10%with the length of only 44?m?0.12?g at 390 GHz?.