| Various wireless applications make the low microwave band increasingly overcrowded in the past years. Accompanying with the rapid development of the semiconductor technology, the wireless techniques in the high microwave band and millimeter wave and even the sub-millimeter wave frequency band attract more and more people’s attention. Nevertheless, the electrical properties of substrate materials, transmission lines and resonant structures usually remain unknown at these frequencies. These basic electrical parameters are needed to be extracted prior to the microwave and millimeter-wave device and system design procedure. Besides, the improvement of passive techniques at microwave and millimeter-wave frequencies would further promote the development of wireless techniques at these frequency bands. In the dissertation, we major in the investigations on the passive techniques at microwave and millimeter wave frequencies, including the electrical characterization of substrate material and transmission lines, investigation of novel resonant structures and related passive device designs as well as verification by experiments. The dissertation is organized as follows:Chapter one does a deep investigation of the loss of substrate integrated waveguide (SIW) cavity resonators and transmission lines. A differential method based on SIW resonant cavity is introduced to separate the loss of substrate material and rough metal surfaces by comparing the unloaded Q-factor of SIW cavity resonators with varied thicknesses. The metal loss of the via-array can be extracted through the comparison of the unloaded Q-factor of SIW cavity resonators with varied widths but the same length. As to the dielectric constant ε’ of substrate material, it can be obtained through optimization algorithm based on Newton-Raphson method with the measured resonant frequencies of SIW cavity resonators. This method has been verified with Rogers5880 by experiments at microwave frequencies from 10-30GHz. A remarkable characteristic of SIW that differs from other planar transmission lines is that the electric field of SIW structures is normal to the substrate surface. There is potential to evaluate the anisotropy of substrate material with this characteristic of SIW. Besides, a relationship is established between the unloaded-Q factors of SIW cavity resonator and attenuation constants of SIW transmission line and summarized as a simple formula. Usually, the errors of attenuation constants extracted from SIW cavity resonators are less than that obtained by Thru-Line method. The work mentioned above is already accepted or published in IEEE Trans. on MTTs, IEEE MWCL, vol.23, no.12,2013 and IEEE APMC2012.Chapter two proposes a triple-mode SIW cavity resonator by placing an additional metallic via at the center of a square or circular SIW cavity. The resonant frequency of the dominant mode increases sharply and become close to that of the second-order degenerate modes. The size of triple-mode SIW cavity resonator remains almost the same as that of dual-mode SIW cavity. The proposed triple-mode SIW cavity retains the advantage of high Q-factor and low loss since it’s a shield structure. Measured results have been compared with the simulated results using the electrical parameters provided by Rogers Corporation. Finally, the gap between simulated and measured results is bridged with the results of the differential method based on SIW cavity resonators introduced in Chapter one. Besides, enhanced operation bandwidth and even better frequency response selectivity can be achieved in the filter design using the triple-mode SIW cavity instead of dual-mode SIW cavity. Part of the work is published in IEEE MWCL, vol.23, no.5,2013.Chapter three focuses on the design of polarization-rotating frequency selective surfaces (FSSs). These FSSs allow for a polarization separation of incident wave and transmitted wave /reflected wave and filtering of the incident wave in a single component. The triple-mode SIW cavity resonator is applied in the FSS design instead of the dual-mode SIW cavity resonator. Comparing with the FSS design with dual-mode SIW cavity resonator, a 57% impedance bandwidth enhancement has been achieved in this FSS design and the frequency selectivity is greatly improved by a transmission zero at its the lower stopband. To improve the FSS performance with oblique incidence, a miniaturization design of polarization-rotating FSS based on the dominant-mode SIW cavity resonator is introduced in this chapter. The FSS design is analyzed with the antenna-filter-antenna (AFA) array concept.In addition, a reflective surface with polarization rotating property is presented in this chapter. The electrical parameters in the FSS designs are also provided by the differential method in Chapter one. Part of the work has been accepted or published in IEEE Trans, on AP, vol.62, no.2,2014, IEEE AWPL, vol.12,2013 and IEEE APMC2014.Chapter four describes the investigation on millimeter-wave and submillimeter-wave techniques based on CMOS (Complementary Metal-Oxide-Semiconductor) and MEMS (Micro-Electromechanical Systems) technology. The propagation property of CMOS microstrip is investigated at the frequency range from 110-325GHz through both the simulation and measurement. Followed by the detailed discussion of the resonator method about the extraction of air-filled waveguide. Then the performance of dominant and overmoded air-filled waveguide cavity resonator has been analyzed and compared at millimeter and sub-millimeter frequencies through full-wave simulation. A set of filters based on the overmoded cavity resonator are designed, fabricated and analyzed. Finally, the investigation of sub-millimeter wave FSS design is presented. A novel "waveguide resonator" structure of good mechanical stability and ease of manufacturing is proposed and applied in the FSS design.
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