Based On The Research Of New Type Of Siw Bandpass Filter

With the developing of modern comminication technologies, some stringent requirements on the RF/microwave devices and subsystems have been proposed, such as planar, miniaturization and high integration etc. Recently, substrate integrated waveguide (SIW) which was proposed as a new guiding structure has been widely used, the advantages of both waveguide and microstrip, such as high Q, low cost, compact size, and easy fabrication, etc. Thus, SIW has been widely used in microwave and millimeter wave circuits including filters, antennas, power dividers, couplers, and some other important applications. It has been a hot research topic to design compact and high performance filters using SIW technology in recent years.In this work, we firstly introduced the SIW structure, and then analyzed its transimission characters and design methods; the design of transition structure between SIW and microstrip was aslo introduced. A more miniaturized structure of quarter-mode SIW was proposed and analyzed; QMSIW is a resonate structure while having just quarter size of SIW, causing more compact and miniaturized size.Then, combined with general chebyshev methods, we designed a QMSIW-based BPF with center frequency of5.5GHz cross-coupling bandpass filter, in which the S-shaped slots is symmetrically etched on the top and bottom metal planes connected by vias to form a phase inverter and produces electric coupling, which provides multiple signal paths where a signal may pass between the input and output ports; thus signal cancellation can take place at given certain frequencies to enhance sharp frequency selectivity.Next, a compact planar bandpass filter is presented, implemented by the combination of three different electromagnetic structures, saying, substrate integrated waveguide (SIW), square complementary split ring resonators (CSRRs) and dumbbells slot. A very wide rejection band ranging from11GHz to23GHz was achieved, indicating quite strong spurious suppression.At last, a LTCC V-band (57GHz-64GHz) cross-coupling bandpass filter was designed. There are many problems such as parasitic effect and radiation loss because of the high frequency, which were discussed in the paper. The design procedures are described and discussed in detail.The prototypes have been fabricated and measured. Good agreements can be observed, indicating the validity of the proposed design strategies.