Microstrip Bandstop Filter Research Articles

A novel configuration of a microstrip metamaterial reconfigurable bandstop filter

This paper presents the design, simulation, and test measurements of a microstrip bandstop filter operating at 1.5 GHz, incorporating six split ring resonator (SRR) unit cells. The substrate employed is an FR-4 with a thickness of 1.6 mm and tangent losses of 0.025. In the initial phase, the design is conceptualized, simulated using computer simulation technology (CST) studio and advanced design system (ADS) Agilent simulators, and validated through test measurements. Building upon this foundation, the filter is transformed into a reconfigurable variant by integrating four SMV2019 varactor diodes. These varactors are modeled to ensure the reconfigurability of the bandwidth. The integration of varactors introduces dynamic tuning capabilities to the considered bandstop filter.

Superconducting Notch Filter for RFI Mitigation in Ground-Based Radio Telescope

This article presents a high-rejection, thin-film high-temperature superconductor, microstrip bandstop filter to prevent a local, and high-power radio-frequency interference (RFI) source from interfering with NASA Goddard Geophysical Astronomical Observatory (GGAO)’s very long baseline interferometry (VLBI) global observing system (VGOS) cryogenic receiver. This filter has an excellent 2.7%, 50-dB-fractional-bandwidth, and a center stopband frequency of 9.41 GHz. It does not contain any narrow or interdigital features as found in some designs, which reduces the fringing electric fields and improves its power handling capability. The YBCO films were grown on 435- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> m-thick R-plane sapphire substrate and the anisotropic behavior was modeled and simulated with a high degree of accuracy. The device was tested while cooled to 77 K and the measurements agree well with simulation.

New Method for the Microstrip Bandstop Filter With a Wide Stopband and an Extremely High Attenuation

A new method for the design of microstrip bandstop filter with a wide stopband and an extremely high attenuation is proposed. At the input and output ports of this bandstop filter, the tight coupling has been adopted for the coupled line with a single-ended ground. Then, a wide bandwidth and a steep slope will appear at the edge of the stopband. Moreover, two coupled bandstop-mode resonators added can result in an extremely high attenuation within the stopband. Two structures are then cascade connected. Eventually, this bandstop filter, with the attenuation of 56 dB and a fractional bandwidth of 68.4%, is developed.

Dual-Band Bandstop Filtering Cable Design Using Defected Conductor Layer With Asymmetric Spiral Structure

In this article, we present a novel dual-band bandstop filtering cable by surrounding inner wire with asymmetric bridge-connected spiral-shaped defected structure on outer conductor. The simulation results demonstrate that the proposed dual-band bandstop filtering cable can be modeled by two parallel RLC resonance circuits in cascade and the performance can be easily adjusted by changing the structural parameters. The well-designed dual-band bandstop filtering cable can be fabricated by core wire surrounding with polytetrafluoroethylene (PTFE) dielectric layer and polyimide defected conductor layer with asymmetric bridge-connected spiral-shaped defected structures. The proposed filtering cable with ten asymmetric bridge-connected spiral-shaped defected resonators on defected conductor layer has a compact size of diameter 1.66 mm and length 200 mm, and its insertion loss in experimental results is greater than 20 dB at 0.88 and 1.3 GHz. Compared with the traditional microstrip bandstop filter, the proposed dual-band bandstop filtering cable can achieve better stopband and passband performance within more compact size. In essence, it is a cable replacement technology, which can improve electromagnetic compatibility (EMC) performance at system level and equipment level, and has the potential to be widely used in wireless system.

Microstrip band-stop filter based on double negative metamaterial

In this work, we present a novel miniature band stop filter based on double negative metamaterial, this circuit is designed on a low-cost substrate FR-4 of relative permittivity 4.4 and low tangential losses 0.002. The proposed filter has a compact and miniature size of 15 mm in length and 12mm in width without the 50 Ω feed lines. The resonator was studied and analyzed with a view to achieving a band-stop behavior around its resonant frequency. The band-stop characteristics are obtained by implementing the metamaterial resonator on the final structure. The obtained results show that this microstrip filter achieves fractional bandwidth of 40% at 2 GHz. Furthermore, excellent transmission quality and good attenuation are achieved. This filter is an adequate solution for global system for mobile communications (GSM).

Design of Planar Wide-Stopband Bandstop Filters With Extra-High Attenuation

The novel microstrip bandstop filters with extra-high attenuation and wide stopband have been proposed. In order to realize the bandstop filter with broad stopband and great attenuation within the stopband, the coupled lines with single-ended ground have been adopted at both input and output ports. Moreover, for a greater fractional bandwidth, a higher impedance ratio <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Z_{ei}/Z_{oi}$ </tex-math></inline-formula> of two adopted coupled lines is required. Furthermore, by differentiating the even- and odd-mode impedances of coupled lines at the input and output ports, the attenuation within the stopband can be increased and the stopband’s bandwidth would be slightly narrower. Two bandstop filters, with the attenuations of 46 dB and 55 dB and a fractional bandwidths of 58.1% and 50.3%, respectively, have been developed to verify the proposed method.

Microstrip Bandstop Filter for Preventing Conduction Electromagnetic Information Leakage of High-Power Transmission Line

The research of transient electromagnetic pulse emission monitoring technology (TEMPEST) protection is essential. Based on microstrip bandstop filter (MSBSF), a method to prevent electromagnetic information leakage of high-power transmission lines is proposed in this paper. The MSBSF with a high insertion loss and carrying large current in the frequency of 2.40–2.49 GHz is designed, fabricated, and experimentally measured. The fabricated MSBSF with the insertion loss of 38 dB at 2.41–2.49 GHz can carry a current greater than 10A and withstand a voltage of 1.7 kV. Compared with the traditional electromagnetic interference (EMI) filter, the MSBSF has the advantages of preventing conducted electromagnetic information leakage in the high-frequency bands, carrying greater current subject to higher voltage, and possessing lighter weight. The MSBSF may be used to prevent the leakage of high-frequency electromagnetic information of high-power transmission lines.

New highly narrowband miniature microstrip bandpass and bandstop filters based on SIR components for wireless systems

ABSTRACT This study presents new miniaturized designs of microstrip multiband bandstop filter (BSF) and multiband bandpass filter (BPF) employing step impedance resonators (SIRs) and RT/Duroid 6010 substrate. The projected bandstop filter can be adopted in applications for removing the interference of narrowband signals from the allocated bands of other wireless systems operated under 2.5, 5.84, and 9.79 GHz. On the other hand, the designed bandpass filter can be used in RF transceivers operating in various isolated narrow frequency bands at operating frequencies of 5.35, 5.555, 6.36, 7.84, 8.385, and 9.5 GHz. The novelty of this paper comes from the considerable smallness of the designed filters and extremely low fractional bandwidths (less than 1%) as compared with numerous reported filters in the literature, especially the superconducting filters. Both filter designs have been verified through measurement, and the measured consequences are in line with the simulation ones.

Design of a switchable microstrip bandstop filter with signal/dual stopbands

Design of a switchable microstrip bandstop filter with signal/dual stopbands

Quasi-Reflectionless Tunable Filtering Antenna for Multicarrier Transceiver

In this letter, a tunable quasi-reflectionless filtering antenna is proposed. The device consists of a reflective microstrip bandstop filter (BSF) and a radiating patch antenna connected in a complementary-duplexer fashion. By terminating the output port of the BSF with another antenna and employing the patch antenna (antenna channel) as the radiator, a tunable quasi-reflectionless antenna is obtained. Since each element works at a specific frequency, the antenna array distributes spectrum resources to different antenna elements, which fits with the multicarrier base station application. The theoretical analysis by equivalent circuits is given. For verification, a dual-band prototype is fabricated and measured. The measured results agree well with the simulation. The filtering antenna exhibits a fractional bandwidth of 3.2% and a tuning range from 3.6 to 4.1 GHz for each band. The maximum radiation gain is 5.5 dBi, making it a good candidate for a multicarrier transceiver in sub-6 GHz 5G applications.

Compact Double Notch Coplanar and Microstrip Bandstop Filters Using Metamaterial—Inspired Open Ring Resonators

Compact double notch coplanar and microstrip bandstop filters are described. They are based on a version of the open interconnected split ring resonator (OISRR) integrated in microstrip or coplanar waveguides. The OISRR introduces an RLC resonator connected in parallel with the propagating microstrip line. Therefore, this resonator can be modeled as a shunt circuit to ground, with the R, L and C elements connected in series. The consequence for the frequency response of the device is a notch band at the resonant frequency of the RLC shunt circuit. The number of notch bands can be controlled by adding more OISRRs, since each pair of rings can be modeled as a shunt circuit and therefore introduces an additional notch band. In this paper, we demonstrate that these additional rings can be introduced in a concentric way in the same cell, so the size of the device does not increase and a compact multi-notch bandstop response is achieved, with the same number of notch bands as pairs of concentric rings, plus an additional spurious band at a higher frequency.

Compact Mechanically Tunable Microstrip Bandstop Filter With Constant Absolute Bandwidth Using an Embedded Metamaterial-Based EBG

A mechanically tunable, constant-absolute-bandwidth (ABW) bandstop filter is realized using the metamaterial-based electromagnetic bandgap structure (MTM-EBG). The MTM-EBG is embedded within a microstrip (MS) line and used to produce a bandstop filtering response, with a topology that is compact, uniplanar, and fully printable. A three-cell MTM-EBG-based MS bandstop filter is designed and experimentally verified for operation centered at 4.18 GHz with a 10-dB rejection bandwidth of 247 MHz. This filter is then made tunable by placing a dielectric plate directly on the surface of the MTM-EBGs. Moving this plate across the surface of the MTM-EBGs changes their reactive loading and, consequently, shifts their response. To ensure a constant ABW, the dielectric plate is perforated to produce an effective plate permittivity that varies for each unit cell. The tunable filter is then fabricated, with the dielectric plate applied to the MTM-EBG-based bandstop filter using a 3-D printed superstructure. A tuning range of 3.80 GHz ± 6.2% and a 10-dB bandstop ABW of 244 MHz ± 1.3% are demonstrated, showing good agreement with the simulated data. The MTM-EBG-based tunable bandstop filter has a variation in ABW comparable to 3-D filters (which typically have substantially lower variation in ABW than fully planar filters) while occupying substantially less area than alternate planar realizations.

Double-Layer Microstrip Band Stop Filters Etching Periodic Ring Electromagnetic Band Gap Structures

The electromagnetic band gap structure (EBGs) is widely used in microwave engineering, such as amplifiers, waveguides, microstrip filters, due to the fact of its excellent band stop characteristics. In this paper, three kinds of microstrip band stop filters were proposed which were etched with a hexagonal ring EBGs, octagonal ring EBGs and elliptical ring EBGs. Firstly, the etching coefficient of a band stop filter is proposed, and the performance of filters with different etching coefficient was analyzed. Secondly, the equivalent circuit of an EBGs band stop filter is proposed. By comparing the simulation results using advanced design system (ADS) and high frequency structure simulator (HFSS), it was found that the simulation results had the same −10 dB stopband width which verifies the correctness of the equivalent circuit model. Finally, three kinds of microstrip stopband filters were fabricated and measured. The experimental results of the −10 dB stopband width and resonant frequency were in good agreement with the simulation results. The −10 dB stopband fractional bandwidth of the three kinds of microstrip stopband filters was more than 63%. The proposed microstrip band stop filters can be widely used in microwave devices with a wide stopband.

Mutual coupling reduction using coupling matrix based band stop filter

The capability of the coupling matrix-based band stop filter in mutual coupling reduction between the MIMO arrays is presented. Initially, a microstrip band-stop filter with 3 GHz center frequency is designed using coupling matrix method. This filter structure is then placed between 2×1 radiating patches separated by 0.22 λ in a reference MIMO antenna designed for 3 GHz WiMAX applications. Both array antennas with/without band stop filters are fabricated and the scattering parameters are obtained separately and plotted comparatively. A good agreement is achieved between measurement and simulation results, and about 28 dB isolation is observed at operating frequency after the proposed filter application. Besides, the Envelope Correlation Coefficient (ECC) is computed and surface current distributions are simulated for both cases. It is observed that ECC has dropped to almost zero and the surface currents induced in the second patch due to the first patch excitation are extinguished with the implementation of the proposed isolation wall. Finally, to clarify the advantages of our approach, a few related studies are summarized in a comparative table.

An Efficient Hybrid Sampling Method for Neural Network-Based Microwave Component Modeling and Optimization

In this letter, we propose an efficient hybrid sampling method for microwave component modeling and optimization. The sampling method adaptively chooses samples from global and local samples to form a data set. The local samples are obtained using a greedy-like sampling method to exploit potential optimal solutions. The global samples are chosen using random sampling with minimum distance rejection to ensure the uniformity of the samples in the design space. The obtained data set is used to establish a surrogate model using the artificial neural networks (ANNs), and the optimal design parameters are obtained by optimizing the ANN model. A bandstop microstrip filter is taken as an example to verify the performance of the sampling method. The results show that the ANN model based on the proposed method achieves better modeling performance and yields better optimal design than the ANN model based on conventional sampling methods.

CIRCULAR DEFECTED GROUND MICROSTRIP BAND-REJECT FILTER DESIGN FOR RADAR COMMUNICATION

In this paper, a novel narrow band microstrip band-reject filter is designed using three circular shape defected ground structure (DGS). Three circular shape defected ground structure are linked by a path in the ground plane where etching process is applied. The path length of middle DGS cell is 8 mm and the path length of corner DGS cell is 11 mm whereas the path width of all three DGS cell is 0.6 mm and the radius of circular shape defected ground structure is 2.1 mm. The mid-stop band frequency of the designed filter is 1.61 GHz which is applicable for the satellite and radar communication for the purpose of S-Band. The stop bandwidth of proposed filter is 1 GHz to 2.2 GHz which is useful for narrowband communication. The proposed filter has minimum return loss of 0.11 dB and maximum insertion loss of 60 dB at mid stop-band frequency 1.61 GHz. IE3D 14.1 EM simulation tool is applied for finding out the desired outcome. The proposed microstrip band stop filter has a coverage area of (35.1 mm× 14.4 mm) 505.44 mm2 for the top layer and (16.6 mm× 19 mm) 315.4 mm2 for the ground layer which is more compact as compared to other existing band stop filter designs.

Design of a miniaturized tri-band bandstop filter using spur microstrip lines and via-hole grounding

PurposeThe purpose of this paper is to propose a miniaturized tri-band bandstop filter that finds application in a modern dense communication system where size and multi-band plays a vital role.Design/methodology/approachIn this paper, the authors propose a miniaturized tri-band microstrip bandstop filter which combines the conventional bandstop filter and spur microstrip line structures such that this design achieves tri-band operation at 1.8 GHz and 3 GHz. The overall length of the microstrip filter is found to reduce from 126 to 45 mm because of introduction of spur lines and via-hole grounding. The addition of spur lines replaces two resonators, introduces two additional resonant frequencies and enhances the −6 dB bandwidth of the center frequency by 14 %.The addition of via-holes in each resonator reduces its length into half of its original length, thereby reducing filter size.FindingsResonance occurs at three different frequencies 1.8, 2.4 and 3 GHz. The filter size reduces from 126 to 45 mm, and the −6 dB rejection bandwidth of center frequency improves by 14 %.Originality/valueThe overall filter size is reduced by 65% and it resonates at three different frequencies 1.8, 2.4 and 3 GHz with an improved bandwidth of 10 % around the center frequency.

Microwave systems design centering exploiting space mapping technology and modified trust region algorithm

AbstractSystem design centering process looks for nominal values of system designable parameters that maximize the probability of satisfying the design specifications (yield function). Statistical design centering implements a statistical analysis method such as Latin hypercube sampling (LHS) for yield function estimation and explicitly optimizes it. In this paper, we introduce a new statistical design centering technique for microwave system design. The technique combines a modified surrogate‐based derivative‐free trust region (TR) optimization algorithm and the generalized space mapping (GSM) technique. The modified TR algorithm is a derivative‐free optimization algorithm that employs quadratic surrogate models to replace the computationally expensive yield function over hyperelliptic trust regions in the optimization process. TR algorithms exhibit global convergence features irrespective the starting point setting. The new design centering approach utilizes the GSM technique to approximate the feasible region in the design parameter space with a sequence of iteratively updated space mapping (SM) surrogates. At each SM iteration, the modified TR algorithm optimizes the yield function for the current SM region approximation to get a better center. Two microwave circuit examples are used to show the effectiveness of the new design centering technique to obtain an optimal design in few SM iterations. In the design process, we employ Sonnet em for the bandstop microstrip filter design and CST Studio Suit for the ultra‐wideband (UWB) multiple‐input‐multiple‐output (MIMO) antenna.

Design of a Band-Stop Planar Filter for Telecommunications Applications

This paper presents the design and the comparison of an Open circuit Microstrip Band Stop Filter using two simulators: CST microwave studio and Advanced design system (ADS). This filter is designed on central frequencies f1=2GHz and f2=4.5GHz. The simulation shows a coincidence between the S-parameter results for the proposed band-stop filter. The rejection band of the band-stop filter is about 76%, else the filter has 25 dB return loss, which characterized by good selectivity.

Triple Notches Bandstop Microstrip Filter Based on Archimedean Spiral Electromagnetic Bandgap Structure

With the development of artificial electromagnetic structures, defective grounding structures (DGS), defective microstrip structures (DMS), and electromagnetic bandgap (EBG) have been widely used in the design of microstrip filters. In this paper, a triple notches ultra wideband bandstop microstrip filter based on Archimedean spiral electromagnetic bandgap structure (ASEBG) structure is proposed. Firstly, the equivalent circuit of ASEBG is analyzed, and L and C values are extracted by using Advanced Design System (ADS). Secondly, the correctness of the lumped parameter model is verified by comparing the High Frequency Structure Simulator (HFSS) simulation results with the measured results. Finally, the influence of ASEBG structure parameters on resonant performance is analyzed by HFSS simulation, and the filter parameters are further optimized. By coupling ASEBG structure to existing double notch microstrip filters, a triple notches ultra wideband bandstop microstrip filter is realized. This method can also be used in the design of other microstrip devices with stopband characteristics. The three bandgap center frequencies of the proposed triple notches ultra wideband bandstop microstrip filter are 3.5, 5.2, and 7.4 GHz, respectively. The corresponding maximum attenuation of the three stopbands is 33.6, 24.8, and 21.7 dB, respectively.