Novel Planar Multimode Bandpass Filters With Radial-Line Stubs

Abstract

Abstract-This paper presents a novel approach for designing planar multimode wideband bandpass filters with good selectivity. The multimode resonator is composed of an open-ended microstrip line with length of half-wavelength (λ/2) and several radial-line stubs. By using different kinds of radial-line loaded stubs, different kinds of responses including three-pole and four-pole bandpass filters can be realized. Depending on electric field distribution and equivalent circuit model, the characteristics of the filter are analyzed. To verify the proposed method, two filters are implemented. The measured results exhibit good agreement with the simulation.

Design and Implementation of Compact Hybrid Four-Mode Bandpass Filter With Multi-Transmission Zeros

“…Dual mode characteristic is produced by introducing perturbation to a ring resonator to split two degenerated modes of the resonator. From then on, various dual-mode [2][3][4][5] and multimode [7][8][9] microstrip resonators and filters have been proposed. By loading a stub to a microstrip resonator, non-degenerated modes can be excited and dual-/multi-mode characteristics can be achieved [4,5].…”

“…By loading a stub to a microstrip resonator, non-degenerated modes can be excited and dual-/multi-mode characteristics can be achieved [4,5]. In [6] and [7], microstrip triple-mode filters were implemented by using a half-wavelength transmission line resonator with a couple of center symmetrical loaded stubs of different lengths or shapes. Microstrip triple-mode filters also can be realized by loading stubs to a loop [8] or adopting fractal defection in triangular patch [9].…”

LTCC Fold-Back Bandpass Filter Designed With Capacitively Loaded Stubs

“…One research by [6] presented an ultra wideband (UWB) filter based on quarter-wave length shortcircuited stubs requiring a minimal number of vias, achieving an extremely wide bandwidth of 109%. Zhang et al [7] developed a wideband bandpass filter with good selectivity using a multimode resonator composed of an open-ended microstrip line with a length of half-wavelength and several radial-line stubs. In reference [8], the study presented an UWB filter with a hybrid microstrip and an implemented slotline structure using a composite series and shunt stubs, possessing higher order transmission poles.…”

“…One is designed with fully distributed elements, and the other utilizes mixed lumped/distributed components. Half-wavelength open-circuited resonators and quarterwavelength short-circuited resonators are most often utilized to be filter resonators, with each having their advantages and disadvantages [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

High Selectivity Broadband Bandpass Filter With Dual-Mode Folded-T-Type Resonator

“…The planar microstrip BPF has attractive features such as easier design, easier manufacture, lower cost, smaller size and lower radiation loss. In the past, a variety of microstrip planar broadband BPFs with improved electrical and/or geometrical features has been investigated [2][3][4][5][6][7][8][9][10][11][12]. Dual-mode resonators are attractive because the number of resonators required for a given degree of the filter is reduced by half, resulting in a compact filter configuration [3].…”