Study And Design Of SIW Bandpass Filters

With the rapid progress in modern wireless communication technology, the microwave filters, as one of the most important components, are widely and deeply researched. With various demands of communication system, more and more new material, novel structures, and new methods are applied to design filters. Recently, substrate integrated waveguide (SIW) was proposed as a new guide wave structure, which combines the advantages of waveguide and microstrip, such as high Q, high power capability, compact size, and easily fabricated. Thus, SIW has been widely used in microwave and millimeter wave circuits including antenna feeders, filters, couplers, oscillations, and other important applications. It is a hot research topic to design compact and high performance filters using SIW technology.The research work presented in this paper focuses on the design methods and unique performance of several types of novel SIW and HMSIW bandpass filters. The primary work is concluded as follows:Firstly, the structure and propagation characteristics of SIW and half-mode SIW (HMSIW) are discussed in this paper. Several typical SIW-microstrip transition structures are introduced. Some SIW inductive coupled resonating bandpass filters are designed and fabricated, and the measured results show these filters have good performance. Then two novel wideband bandpass filters are realized by combing SIW with complementary split-ring resonator (CSRR) and split-ring resonator (SRR) defected ground structure (DGS) respectively. The measured results proved the utility and practicability of the proposed design methods.Finally, two types of wideband bandpass filters are proposed by integrating HMSIW with spiral compact microstrip resonating cell (SCMRC) and periodic dumbbell shaped DGS. Besides, an Ultra-Wide Band (UWB) bandpass filter is implemented by integrating HMSIW with EBG structure, and a frequency notch is generated by embedding spur-lines in the HMSIW-to-microstrip transition. The design methods and design process of these filters are discussed in details. The good agreements between measured and simulated results prove the practicability of the proposed methods.