Quintuple-mode wideband bandpass filters with improved out-of-band rejection

Abstract

This paper presents design of quintuple-mode wideband bandpass filters, implemented with off-centered perturbed metallic cylinders in a rectangular waveguide cavity. Three perturbation cylinders are placed at the bottom of the rectangular waveguide cavity, along with a pair of perpendicularly fed coaxial lines; excite five quasi-transverse magnetic modes to realize the desired passband. The height of the waveguide cavity and the shape of the perturbation cylinders are exploited to shift the resonant modes far away from the passband and achieve a good out-of-band rejection and sharp skirt selectivity. The filter operates at the center frequency of 2.68 GHz with a wide fractional bandwidth of 43%. The proposed filter is fabricated with aluminum. The measured and simulated results are in good agreement with each other.

A wideband bandpass filter with wide upper stopband attenuation containing multiple resonators

“…Besides, multimode resonators (MMRs) are widely adopted to design wideband BPFs, which have the advantage of compact size, simple structure, and high performance. 7 The MMRs are usually a variety of variations: such as stub loaded, stepped impedance and ring, and so on. A triple-mode wideband BPF exhibit fractional bandwidth of 69.1% based on MMR is presented in Zhang et al, 8 the MMR is constructed by double Tshaped stub and uniform impedance resonator.…”

“…In Xu & Zhang, 6 a simple wideband BPF with multiple transmission zeros utilizing three pairs of coupled lines is proposed. Besides, multimode resonators (MMRs) are widely adopted to design wideband BPFs, which have the advantage of compact size, simple structure, and high performance 7 . The MMRs are usually a variety of variations: such as stub loaded, stepped impedance and ring, and so on.…”