Design and Fabrication of Tri-Stopband Bandstop Filters Using Cascaded and Multi-Armed Methods

Abstract

In this paper, we proposed a compact C-open-loop ring resonator and its equivalent circuit. The second cascaded bandstop filter (BSF) are designed using this simple C-ring resonator. The double ring BSF consists of two cascaded Cring resonators, which are placed on the RO4003 substrate, while the other triple BSF structure consists of tree cascaded C-ring resonators, which are connected with input and output through microstrip feed lines. The both filters are simulated, optimized and partially realized using MWR simulator and Anritsu E5072A vector network analyzer VNA. In order to reduce the size and to improve the filter characteristics, novel compact filter topologies are designed basing on the previous structures. The proposed multi-band BSFs consist of several open-loop ring resonators placed vertically overlapping (coupled multi-armed ring resonator). Using this idea, the filter topologies with design flexibility, close size and excellent results are reached. The novel compact multi-band BSFs produce several stopband along a frequency range from DC to 9 GHz, in which each separate band exhibits an acceptable and useful bandwidth. Each stopband has regenerated two reflexion zeros, what leads to a good sharpness factors in the transition domains. Good agreement between the experimental results, full-wave simulation has been achieved. Such compact and flexible filters can be successfully used in several microwave and in modern wireless and mobile/satellite communication systems.

Design of Triband Bandstop Filter Using an Asymmetrical Cross-Shaped Microstrip Resonator

“…The proposed filter is more compact than those in [9] and [10]. It has deeper rejection levels than those in [6], [9], and [10]. The filter in [11] has the deepest rejection levels and smallest size.…”

“…The wavelength refers to the guided wavelength at the lowest resonant frequency. The proposed filter is more compact than those in [9] and [10]. It has deeper rejection levels than those in [6], [9], and [10].…”

“…Triband microstrip BSFs have not been widely investigated. Only a few papers on triband BSFs are found [2][3][4][5][6][7][8][9][10][11]. In [2], a pair of coupled lines and a modified spurline are used to generate three stopbands, but the insertion losses in passbands are high.…”

“…Three deep stopbands are generated around 2.37, 3.54, and 5.01 GHz. In [10], three cascaded C-ring resonators are used to generate three wide and deep stopbands. In [11], two folded trisection stepped impedance resonators are used to generate three deep stopbands.…”

Tunable Multiband Balanced Bandstop Filter With High CMRR

“…8). Further miniaturization can be achieved by implementing all the immittance inverters using lumped elements, multilayer technique, open-loop ring resonators or defected ground structure (DGS) slots as discussed in [18][19][20][21]. All the immittance inverters used as the couplings in the design are quarter wavelength long at 1.45 GHz, which is the center frequency of overall spectral range of the designed balanced dualband tunable BSF.…”