Multiple-Mode Wideband Bandpass Filter Using Split Ring Resonators in a Rectangular Waveguide Cavity

Abstract

This paper presents a simple split ring resonator excitation to realize a multi-mode wideband bandpass filter in a rectangular waveguide cavity. The proposed resonator employs two rectangular split rings attached with two coaxial probes extended into the cavity to excite two resonant modes, unlike the conventional cavity resonators which employ conductive cylinders in the cavities to achieve the same results. A hybrid magnetic (HM) mode and a hybrid electric (HE) mode are the two hybrid modes excited to realize the wideband bandpass filter. The filter operates at 2.5 GHz center frequency with 53% fractional bandwidth. Finally, the prototypes of a second and a fourth order filter are fabricated for results validation. Measured results are in good agreement with the simulated ones.

Application of a Stub-Loaded Square Ring Resonator for Wideband Bandpass Filter Design

“…However, the bandwidth is controlled by the coupling gap and thus large bandwidth would be limited due to the requirement of the precious fabricated technology. In [16,17], wideband BPFs were implemented using multiple-mode split-ring resonators in a rectangular waveguide cavity. However, the above design procedure and/or structure are complex.…”

“…At present, most of the research and applications of the BPF still focus on the broadband and multi-band design [1,2]. In the past, several resonator structures have been proposed to achieve the wideband filter design, such as the use of the step impedance resonator (SIR) [3,4], defect ground structure (DGS) [5], multi-layer structure [6], multi-mode (MMR) [7][8][9], stub-loaded resonator (SLR) [10][11][12][13], coupled-line [14,15], multiple-mode split-ring resonators (SRR) [16,17], and so on.…”

Quadruple-Mode Wideband Bandpass Filter with Improved Out-of-Band Rejection

“…To be eligible for the base-station employments in a wireless communication system, miniaturization of the waveguide cavity filters is very much in demand. One of the methods to achieving miniaturization of cavity filters is the usage of multi-mode resonators (MMRs) [6][7][8][9][10]. Lin [11] was the first to design an MMR filter in 1951, after which many MMR filters were designed using several perturbation methods, such as half-cut dielectric loading [12,13], screws [14], irises [15,16], and corner-cuts [15,17].…”

An Ultra-Wideband Bandpass Filter with a Notch Band and Wide Upper Bandstop Performances

“…In the past, several UWB-BPF design methods have been proposed [4][5][6][7][8][9][10][11][12][13][14][15][16]. In [4], the steppedimpedance resonator (SIR) was used to effectively obtain the wideband performance by controlling the spurious frequencies.…”

“…In [14], a wideband BPF was directly designed by using composite series and shunt resonators. In [15,16], a wideband BPF was realized using multiple-mode split-ring resonators in a waveguide cavity. However, it is still a challenge to design a UWB-BPF without using a complex design process and structure to achieve a notch band, good band isolation and wide stopband response, simultaneously.…”