Planar wideband band-stop filter with T-inverted shaped open stubs for wideband applications

Abstract

This paper presents a wideband band-stop filter (BSF) structure designed by using planar technology. The proposed filter consists of a modified conventional band-stop structure with open stubs, inner T-inverted shape, and two input/output feed lines. Based on series of optimization and a specific design method, two compact filters with good electrical performance are obtained. In order to characterize the frequency response of the proposed filters, the performance is carried out numerically using two different solvers (Advanced Design System -Momentum and CST-MWS). Furthermore, in order to validate the conception approach, two circuits are designed, fabricated, and tested. Additionally, an equivalent circuit of the wideband BSF is built to estimate the electromagnetic simulation results for practical realization. The features of the design have a reduced size, wideband rejection, and higher insertion losses, which can be performed by adjusting the L-shaped stubs (23.25 × 2.2 mm2) toward the 50 Ω input and output ports. Two filters are designed, fabricated, and tested; one can be operated between an fractional bandwidth (FBW) of about 50% at a center frequency of 1.8 GHz, and the other can be switched from an FBW of 43.38% at a center frequency of 1.82 GHz. In addition, good agreement between the simulation and the measured results is achieved. The overall size of each filter is 43.4 × 34.5 mm2.

Design and Analysis of Microstrip Low Pass and Bandstop Filters

“…An open stub T-inverted topology with ultra compact design of band stop filter in presented in [20]. This filter has compact size of 43.4 mm x 34.5 mm attained 900 MHz bandwidth with return loss (>20 dB) at cut-off frequency of 1.80 GHz.…”

Bandpass filter using coupled‐line‐stub cascaded structure with high stopband rejection

“…In recent years, some methods have been introduced to design the high-performance filters. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] A novel BPF, composed by three pairs of parallel-coupled lines, is designed with high stopband suppression and steep roll-off skirt in Reference 1, but its bandwidth was limited. In Reference 2, the concept of transmission zero (TZ) resonator pairs was proposed to design a BPF, in which the TZ pairs are symmetrically located at the out-of-band.…”

“…Based on transversal signalinterference method, wideband BPF, 8,9 lossy flat-passband BPF, 10 dual-band BPF, 11 and quasi-reflectionless filters 12 are reported, where the energy cancellation generates TZs to improve out-of-band rejection level. In addition, some other types of filters have been extensively researched, such as tunable filters, 13 bandstop filters, 14,15 and so on.…”

“…As one of the most important microwave components, bandpass filters (BPFs) with low in‐band insertion losses and high out‐of‐band rejection levels are extremely desirable in the modern wireless communication systems. In recent years, some methods have been introduced to design the high‐performance filters 1‐15 . A novel BPF, composed by three pairs of parallel‐coupled lines, is designed with high stopband suppression and steep roll‐off skirt in Reference 1, but its bandwidth was limited.…”

Band-pass filter based on complementary split ring resonator

“…However, improving their performances, reducing complexities, and cost of design and manufacturing represent mainly key elements as part of an industrial process for equipment supporting radiofrequency devices [1][2][3][4][5]. Which presupposes the use and implementation of techniques to optimize, miniaturize and improve the microwave circuits constituting these systems to ensure excellent and precise transmission and/or reception [6][7][8][9][10][11].…”