Bandpass Filter For Applications Research Articles

Development of a Tunable First Order Wide Bandpass Active Filter for Communication Systems

In this research, a tunable first-order wide bandpass active filter (BPAF) is developed especially for contemporary communication systems where frequency, flexibility and adaptability are crucial. Because of their limited ability to adapt to changing operating conditions, conventional fixed-frequency filters are inappropriate for dynamic systems such as Software-Defined Radio (SDR) and multi-band communication platforms. Using operational amplifiers and variable passive parts like resistors and capacitors, this paper describes the design theoretical analysis and real-world application of a first-order tunable bandpass filter. With a frequency range of 1 kHz to 10 MHz and an adjustable bandwidth of 100 Hz to 2 MHz, the tunable BPAF is perfect for both narrow and wideband applications. Circuit simulation hardware prototyping and testing with function generators and oscilloscopes are all part of the design process which assesses the circuit noise performance gain, stability and frequency response. The findings show low harmonic distortion and superb tuning accuracy preserving steady performance over the whole operating range. When real-time frequency adjustment is required in communication systems, this tunable filter offers substantial benefits by offering flexibility and dependability in demanding settings. Higher-order designs for more precise frequency roll-offs and enhanced selectivity may be investigated in future research.

High-order Mode of Spoof Surface Plasmon Polaritons based on a Novel Compact Structure and its Application in Band-pass Filters

High-order Mode of Spoof Surface Plasmon Polaritons based on a Novel Compact Structure and its Application in Band-pass Filters

A dual-function tunable terahertz multiband bandpass filter based on PET woven-wire meshes with conductive coating surfaces

A multifunctional terahertz (THz) device with frequency tunability, amplitude modulation and spectral filtering abilities, and substrate flexibility is highly desired for various applications, such as THz communication, sensing, wearable optoelectronics. Therefore, this study proposed a 3D artificial material based on a flexible polyethylene terephthalate (PET) woven-wire mesh with conductive coating surfaces. This material was conceptually demonstrated in experiments as a dual-functional THz device. In addition, the transmission properties of this artificial material were experimentally and numerically explored with reasonable agreement. Then, the underlying mechanism of the spectral characteristics was qualitatively elucidated. The amplitudes and frequencies of the spectral characteristics were successfully validated to be passively manipulated by tailoring the structural parameters of a unit cell and changing the surface conductivities of a device. This process opened the application feasibility of a frequency tunable bandpass filter and a power switch at the THz regime. For the bandpass filter application, the tri-frequency modulation capability was experimentally demonstrated, and a frequency tuning bandwidth of 0.249 THz was achieved by varying the conductivity of the device’s surface-coating layer from 0.44 to 77 MS/m. For the power switch application, the largest modulation depth between the on and off states of a device was successfully demonstrated at approximately 21.3 dB at 0.271 THz. This dual-function THz device has the advantages of compactness, low cost, and easy fabrication, thus providing an alternative strategy to develop tunable, flexible, and versatile THz devices for broad applications.

Inductively Compensated Coupled-Line Resonator and Its Bandpass Filter Applications

Inductively Compensated Coupled-Line Resonator and Its Bandpass Filter Applications

Diagnosis of rotating machine defects by vibration analysis

This work presents the analysis of the vibration signals of a ball bearing, the signals available on the platform Case Western Reserve University in the form of MATLAB files. By proposing an approach for the diagnosis of any rotating machine and detects the failed components in a simple way, the proposed approach consists of several methods and steps each complementary to the other. First on decomposing the signal by the feature mode decomposition (FMD) method and then, according to the Kurtosis values by selecting the useful signals after the selection by computing the sum of the useful signals called the residual of the original signal. The simplicity of the form of the residual makes through the application of band pass filtering and Hilbert transform, but the analysis of the peaks represents the frequency of the failed components.

Inverse design of magnonic filter

Monochromatic spin wave (SW) is the substrates for the realizing the practical function of magnonic devices, however the generating perfect monochromatic SW is still a unsolved but fundamental problems. In our latest work (Xing et al., 2022), the resonant tunneling effect was found in a magnonic crystals (MCs), which demonstrates a similar effect of Fabry–Pérot interferometer, and shows a promising application of band-pass magnonic filter (MF) for generating perfect monochromatic SW. The optimization of such MF is a complex problem, due to that the natural nonlinearity of spin-wave scattering behavior enhances sensitivity to device parameters. In this work, the inverse design (ID) approach is developed for designing the magnonic filters (MFs). To determine the optimizable variables, the fundamental properties of antiferromagnetically coupled heterojunction based MCs were theoretically investigated. The particle swarm algorithms (PSA) is used for automatically finding MFs which meet the inputting requirements. Here, the input of algorithms is a vector of SW frequency and output is a vector of parameters of MFs. Besides, the PSA is further optimized to be self-adapting to required accuracies, showing a higher computing efficiency than the convectional one. Finally, the output data of predicted MFs with various filtering characteristics are briefly summarized in a table as an alternative proposal for the future experimental design. These encouraging results show high potential of using ID approach in magnetism and boosting optimization of magnetic multilayer heterojunction devices, such as magnon transistor and magnon space–time crystals.

Theoretical analysis of VO2 filled double rectangular cavity-based coupled resonators for plasmonic active switch/modulator and band pass filter applications

In this paper, we have designed an electrically tunable nano-plasmonic waveguide-based band pass filter which works on the phenomena of phase transition of Vanadium dioxide. The device operates on telecommunication wavelength and can work as a modulator and a switch with a modulation depth of 26.40 dB. It has shown its promising applications in the area of filtering by providing a high-quality factor of 156. Whereas, the modulation depth and quality factor of the device can be increased and decreased by changing various device parameters. A large tunability of 280 nm in the resonant wavelength is achieved by changing the applied voltage on the device between 0 V and 2.7 V in switch-on and switch-off states. Figure of merit of 12 is also attained by the device. Our device consists of a main waveguide which is coupled to two uneven length rectangular cavities filled with Vanadium dioxide. Active material present as the dielectric of rectangular cavities transforms its state from insulator to metallic and vice versa according to the applied voltage. However, single band transmission is obtained for the device and this can be tuned by changing different geometrical parameters of the device. The device can find its applications in nano plasmonic on-chip applications due to its small size, good modulation depth, and large quality factor with moderate loss.

Моделирование полосно-пропускающих фильтров на основе многослойной технологии

One of the integral parts of modern radio transmitting devices are bandpass filters that limit the out-of-band spectrum of electromagnetic radiation and the side effect of electromagnetic radiation, which is important in the framework of the dense distribution of the radio frequency band between radio services. Similar functions of bandpass filters are made as part of radio receivers and placed at the input. At the same time, they also perform the functions of a matching device between the radio receiving connection and the antenna-feeder path. Currently, there are known methods for the development of bandpass filters based on microstrip technology, which has such advantages as: a broad theoretical base, manufacturability, a wide selection of dielectric bases, and the possibility of simulation without using expensive software. At the same time, the disadvantage of microstrip technology is the need to expand the area of dielectric bases with an increase in the number of frequency-selective elements. Currently, a promising direction in the implementation of bandpass filters is their design based on a multilayer technology, which makes it possible to increase the number of frequency-selective elements without expanding the area of dielectric bases. Purpose of the study. The purpose of this article is to study the frequency-selective properties of design options for a bandpass filter based on multilayer technology, the basic element of which is a microstrip transition. Materials and methods. For the considered designs of the bandpass filter, a numerical electrodynamics simulation was carried out in the ANSYS HFSS software with an estimate of the dependence of the S-parameters in the frequency range of 0.2–4 GHz. The graphical distribution of the electromagnetic field in the microstrip transition was obtained. Results. From the results of the simulation it follows that the considered designs of the bandpass filter are characterized by good matching with a wave impedance of 50 Ohm (VSWR no more than 1.5 in a wide frequency range), low attenuation at the center frequency (no more than 0.5 dB), and by significant suppression of a signal outside its bandwidth (more than 30 dB). Conclusion. The simulation results prove the possibility of practical application of bandpass filters, developed on the basis of multilayer technology, as part of radio transmitting devices of radar and radio navigation systems.

Coplanar waveguide‐serially‐connected coplanar strip dual stub structure for wideband bandpass filters

In this paper, a kind of coplanar waveguide (CPW)-fed series stub structure is proposed and its application in wideband bandpass filters (BPFs) is developed based on the coplanar strip (CPS) dual stubs. Compared with its conventional CPS dual-series-stub counterparts, the proposed one excited by even-mode CPW lines possesses enhanced immunity against unexpected resonance of the CPS-based series stubs. By virtue of this attractive performance, desired resonance can be well realized with predicted in-band characteristics. Subsequently, the application in its constituted wideband BPFs is investigated with synthesis design method. In final, one third-order and one fifth-order BPFs are designed, fabricated, and measured to verify the proposed structure. Measured results are found in reasonably good agreement with the synthesized and the simulated ones.

High-Order Mode of Spoof Surface Plasmon Polaritons and Its Application in Bandpass Filters

A bandpass filter (BPF) with a notched band is designed based on the high-order mode of spoof surface plasmon polaritons (SSPPs). The high-efficiency passband is developed from the first high-order mode (Mode 1) of SSPPs. Compared with the fundamental mode having low-pass response, the Mode 1 has the inherent bandpass response; thus, the BPF generated by Mode 1 does not need to add an additional high-pass filtering structure and employ a gradient transition structure for excitation. The Mode 1 of SSPPs can be effectively excited just with a simple trapezoidal transition converting the signals from microstrip line to SSPP waveguide. Moreover, by embedding a U-shaped resonator into the SSPP structure, a BPF with a notched band is constructed, where the location of the notched band will be red-shifted as the length of resonator increases. The measurements of two fabricated prototypes agree with the simulated ones, which verify the feasibility of our design.

Design of Metal Insulator Metal based Square Ring Resonator Plasmonic Filter using Silica Slits for Dual Band Applications

In this paper, Metal-Insulator-Metal (MIM) based dual-band plasmonic bandpass filters (BPF) with single and dual silica slits design and analysis is presented. The Square Ring Resonator (SRR) is coupled using Coupled feed line for dual-band operations. The coupled feed line is used for dual-band operating wavelengths, 1300 nm (230.6 THz) and 1600 nm (187.37 THz). Design and simulations are performed using complex electromagnetic simulatorknown as computer simulation technology (CST) microwave tool. The proposed filters are used for plasmonic single and dual-band bandpass filter (BPF) applications in photonic integrated circuits (PIC’s).

A compact SIW bandpass filter using DMS-DGS structures for Ku-band applications

This paper presents a design of compact SIW (substrate integrated waveguide) bandpass filter for application in Ku-band Transmit up-convert frequency (i.e., 13.7–14.1 GHz) used for satellite communications. Based on Defected Microstrip Structure-Defected Ground Structure combination (DMS-DGS), this SIW filter structure is designed to improve passband and stopband performance. By merging circular ring slot (CRS) with interdigital DGS, better passband characteristics with sharp stopband attenuation are obtained. To validate the design, the filter is fabricated using Rogers substrate. The size measures 23.8 mm × 10 mm and operates at a center frequency of 13.9 GHz. Measured results of the filter agree well with the simulated results. Also, designed BPF filter has advantage of low insertion loss, better return loss, compact size and high stopband rejection.

Realizations of lossy and lossless capacitance multiplier using CFOAs

This paper presents a new Current Feedback Operational Amplifier (CFOA) based grounded capacitance multiplier (GCM) generic circuit. Lossy and lossless five GCM circuits were realized using this generic circuit. The lossless GCM circuit is studied in detail. The proposed lossless GCM includes two CFOAs, two resistors, and a grounded capacitor. Passive component matching conditions are not needed. In ideal and non-ideal conditions, the sensitivity analysis of the multiplication factor was performed. The effects of non-ideal conditions on the operating frequency range of the proposed GCM were investigated by mathematical analysis. The low-frequency performance has been improved by using a negative impedance converter (NIC). Functionality, time, and frequency domain analyzes were carried out using the LTspice simulation program. The voltage-mode band-pass filter application is included to demonstrate the usefulness of the circuit. The temperature dependence of the application example has been investigated. Monte Carlo analysis was carried out to verify the application example’s robustness against the variation of the passive elements. In addition, a comparison with circuits in the literature is given to show the superiority of the proposed GCM.

Proposal of Coplanar Stripline Series Stub Structure for Wideband Bandpass Filters

In this article, a simple kind of coplanar stripline (CPS) open-circuited series stub structure and its application in wideband bandpass filters (BPFs) are proposed and developed. Compared with its conventional dual-shunted CPS series stub counterparts, the proposed one is capable of achieving desired characteristics as the specified transmission-line (TL) prototypes behave. Based on such equivalent prototypes, three types of CPS open-circuited series stubs are then investigated to reveal the immunity against unexpected resonance caused by the underlying surface-wave-like mode. For demonstration, two examples, a second-order and a third-order wideband BPFs, are synthetically designed for equal-ripple Chebyshev response with prescribed fractional bandwidth (FBW) and return loss (RL). Finally, these two proposed filters with a respective FBW of 49%/70%, an RL of 16.426 dB, and a central frequency of 2 GHz are synthesized, simulated, fabricated, and measured. Measured and simulated results are reasonably in good agreement with each other, thus firmly validating the flexibility of the presented CPS series stub structure in the application of wideband BPFs.

Regression Variance of Nanometre Wavelength and Transmittance Percentage of Chromium Doped Phosphate Glasses

A high transmittance phosphate glass which has the application of band pass filter. The glass was prepared by melt quenching technique method. The main objective is to determine the correlation and regression variance of nanometre wavelength and transmittance percentage values to know the influence chromium on prepared glass. It is found that there is positive correlation between wavelength and transmittance percentage through the glass. The regression coefficients value is a=400.4 and b= - 0.605. The regression value is 326.2.

Inter-connected coupled lines Resonator topology for bandpass filter application

This paper presents an inter-connected side-shorted coupled-line resonator topology as a base cell. The base cell is built from two single-shorted quarter-wavelength coupled-line sections, connected in series to give a half-wavelength coupled-line that creates a single resonance of bandpass filter response. Higher-order bandpass filter is produced by adding new single-shorted coupled-line sections, cascaded in an inter-connected manner to the base cell. This new topology creates a unique arrangement that caused cross coupling effects between the resonators, resulting to the occurrence of transmission zeros that lead to the improvement of selectivity of the higher order bandpass filter response. For validation of concept, 2<sup>nd</sup> and 3<sup>rd</sup> order bandpass filters were fabricated using microstrip technology on Roger 3210 substrate with parameter of <em>Ɛr</em> = 10.2, <em>h</em> = 1.27 mm and <em>tan δ</em> = 3x10-3. The filters were measured and the results show good agreement with simulation results.

An Oscillation-Based Bandpass Filter With a Structure of Two Magnetically Coupled Orthogonal Cantilevers

In this article, an oscillation-based bandpass filter with a structure of two magnetically coupled orthogonal cantilevers was proposed for the first time. Two magnetically coupled orthogonal cantilevers with a frequency ratio of 1:2 was adopted, including an input cantilever and an output cantilever. When the input cantilever was driven to resonance directly by a sweep periodic excitation force, a rectangular-like <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$A$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f$ </tex-math></inline-formula> curve was observed in response to the output cantilever theoretically because of internal resonance, which showed great potential for bandpass filter applications. A macro prototype with a center frequency of 73.1 Hz and a 3 dB bandpass width of 6.2 Hz was developed for experimental verification. The experimental results showed that the output signal in the passband was generally linearly related to the input signal as the voltage of the input signal was in the range of 200–600 mV. In addition, the passband ripple could be greatly improved by limiting the deviation of modal frequency ratio by adjusting the center distance of the two magnets in the range of 7.5–8.0 mm. The proposed oscillation-based bandpass filter provided a new idea for the design of filters. Compared to some conventional electronic filters, it possesses a higher reliability and is immune to electromagnetic noise, which is capable of filtering signals in extreme environments, such as high-temperature environment and strong-electromagnetic-noise environment.

Closed-loop ring resonator topology for bandpass filter applications

&lt;p class="Pa41"&gt;This paper presents a single mode pseudo-elliptic bandpass resonator based on closed-loop ring topology. The resonator is built from six quarter wavelength transmission lines to form a square closed-loop ring structure. This structure creates transmission zeros at the lower and upper sidebands so that high selectivity bandpass filter response is achieved. The advantage of this topology is that the design is less complex since no perturbation is needed on the ring lines for creation of transmission zeros. Higher-order filters can be constructed by introducing quarter-wavelength coupled-lines, coupled at both input and output of the closed-loop ring resonator. For proof of concept, the filters are designed at 10 GHz up to 3&lt;sup&gt;rd&lt;/sup&gt; order, simulated using full-wave electromagnetic simulator on microstrip substrate, &lt;em&gt;FR-4&lt;/em&gt; with characteristics given as &lt;em&gt;Ԑr &lt;/em&gt;= 4.70, &lt;em&gt;h &lt;/em&gt;= 1.499 mm and &lt;em&gt;tan δ &lt;/em&gt;= 0.012. The filters are simulated and responses are found to be agreeable with the proposed idea.&lt;/p&gt;

The application of a Morlet wavelets bandpass filter in the fault diagnosis of rolling bearings

An improved demodulation approach is proposed for the construction of a bandpass filter and determination of its parameters. An envelope analysis of the relationship among the central frequency, bandwidth and the system’s damping coefficient was conducted and it was demonstrated that to extract the fault features effectively, the quality factor of the bandpass filter should remain constant and the bandwidth should be determined according to the damping coefficient of the system, the central frequency of the filter, and the fault frequency of the bearing. A combined wavelet bandpass filtering function was constructed based on the Morlet wavelet function. The capture of fault signals from the rolling bearing was optimized in virtue of excellent bandpass filtering properties of the combined wavelet’s better response and the strong sensitivity of the correlated kurtosis to periodic pulse signals. The experimental test data and the simulation results demonstrated that the proposed approach is an effective method for fault diagnosis of rolling bearings.

Optical characterization of plasmas produced by concurrent application of laser and high voltage pulses

Laser Induced Breakdown Spectroscopy (LIBS) is a simple, powerful analytic technique that is limited by a relatively low sensibility to detect traces. To improve LIBS sensitivity an option often used consists in applying a second source of excitation such as an electric discharge. This work’s goal is to investigate the interaction of a laser-produced plasma on an aluminum target with a self-triggered electric discharge. The plasma dynamics has been investigated using shadowgraphy, fast photography and the application of narrow band-pass filters to follow the evolution of the ionic and neutral species. Results show that within the initial microseconds, the spatial extent of the laser-produced plasma increases due to the presence of a low density region induced by the spark channel. Furthermore, it was found that the electric arc mainly re-excite the ionic species while the neutral ones remains unaffected.