Microwave Bandpass Filters for Wideband Communications

multi-mode resonator have demonstrated many unparalleled attractive features, including a simple design methodology, compact size, low loss and good linearity in the wide passband, enhanced out-of-band rejection, and easy integration with other circuits/antennas. A conventional bandpass filter works under single dominant resonant modes of a few cascaded transmission line resonators and its operating bandwidth is widened via enhanced coupling between the adjacent resonators. However, this traditional approach needs an extremely high coupling degree of coupled-lines while producing a narrow upper stopband between the dominant and harmonic bands. As a sequence, the desired dominant passband is restricted to an extent less than 60% in fractional bandwidth. To circumvent these issues and break with the tradition, a filter based on the multiple resonant modes was initially introduced in 2000 by the first author of this book. Based on this novel concept, a new class of wideband filters with fractional bandwidths

larger than 60% has been successfully developed so far. This book, presents and characterizes a variety of multi-mode resonators with stepped-impedance or loaded-stub configurations using the matured transmission line theory for development of advanced microwave wideband filters. [Publisher's Text]

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