Filter Design Research Articles

A Novel Allpass IIR‐Based QMF Design With Applications in Complex Wavelets

ABSTRACTIIR filter realizations in QMF structures has long suffered from stability problems. A novel design for quadrature mirror filter (QMF) IIR filter bank is presented and implemented in two different applications, namely, subband coding and discrete/complex wavelet transform. The proposed design is based on an allpass filter design for a stable IIR filter satisfying maximally flat passband amplitude conditions and prescribed regularity constraints. Then the proposed design is extended for QMF filter bank structure that can be applicable in different types of wavelets. Output samples of unstable filter realizations in the synthesis QMF part are calculated from inverse allpass filtering along with time‐reversed operations. A method for time‐reversing operations is presented to calculate the final PR (perfect reconstruction) QMF output signal. The proposed design is also extended to complex wavelets and is applied on both upper and lower trees and its dual transform structure. Frequency response graphs for the developed filter designs are presented along with time‐reversed signal simulations.

Design of a dual-band bandpass filter with shunt stubs for wireless local area network and satellite communication system

High-performance radio frequency (RF) modules are required in transmitter and reception devices due to the recent expansion of wireless technology. The power amplifier, low-noise amplifier, filter, and mixer are the most crucial components in the RF transmitter/receiver chain. This work presents the design and analysis of a dual-band bandpass filter (BPF) for wireless local area network (WLAN) and C-band satellite applications. Stubs of the proper electrical length that are open and short-circuited are used to implement the filter. The low pass performance is generated by the open-circuited stubs. Short-circuited stubs achieve high-pass performance, while the combination of open and short-circuited stubs achieves bandpass performance. We confirm the filter's behaviour using the advanced design system 2022 simulation tool. The findings of return loss and insertion loss confirm the simulation-level performance analysis of the filter. The result demonstrates the suggested BPF's dual-band behaviour at 4 GHz and 6 GHz.

Penerapan Strategi Desain Pasif sebagai Optimalisasi Pencahayaan Alami dalam Kenyamanan Visual Bangunan

The Education Building is one of the public spaces that must pay attention to the need for visual comfort needed by students to study productively. The author researched to evaluate visual comfort in the Dean's Building, Faculty of Public Health, Diponegoro University. The method used in this study is a quantitative approach which is carried out by conducting simulations using Revit Lighting Analysis software as data collection to determine the performance of the building. The resulting data was in the form of a diagram of the lighting level in the building. The data from the study explained that the dean's building of the Faculty of Public Health has not met the lighting standards, the building tends to receive excessive sunlight on the west and east sides but the lighting does not stretch on the building, so that some sides of the building lack lighting which the author can conclude that the intensity of space lighting is influenced by the natural lighting obtained from the opening of each room. The design of sun shaders and sun filters in the form of secondary skin is an effort to minimize excess light that enters and expands openings on the sides of buildings that do not receive sunlight. After the redesign, the lighting intensity on the west and east parts began to decrease and was close to the lighting standard. This study explains that the provision of sun shaders and sun filters in the form of secondary skin can optimize natural lighting in a building.

A generalized deep learning framework for inverse design of multilayer spatial filters under wide-angle incidence

A generalized deep learning framework for inverse design of multilayer spatial filters under wide-angle incidence

Developing a novel approach for passive damped LCL filter and controller parameter design using PSO algorithm in VSC-based islanded microgrids

Developing a novel approach for passive damped LCL filter and controller parameter design using PSO algorithm in VSC-based islanded microgrids

Design and Implementation of FIR Filter for 5G OFDM Communication

The advent of fifth-generation (5G) wireless communication technology marks a transformative era characterized by unprecedented demands for high data rates, low latency, and enhanced signal integrity. This thesis presents the design and implementation of a Finite Impulse Response (FIR) filter optimized specifically for Orthogonal Frequency Division Multiplexing (OFDM) systems, a core technology underpinning 5G networks. Given the susceptibility of OFDM signals to inter-symbol interference (ISI) and out-of-band emissions, the need for effective filtering solutions is paramount. This work emphasizes the role of FIR filters in mitigating such impairments while maintaining system performance within the stringent requirements of 5G. Employing hardware description languages (HDLs), the FIR filter architecture is meticulously designed and simulated, allowing for an in-depth analysis of its performance under diverse operational scenarios. Innovations in filter coefficient generation and architectural optimization are explored, resulting in a design that not only achieves improved spectral efficiency but also optimizes resource utilization and processing speed. Rigorous testing and verification demonstrate the filter's effectiveness in enhancing signal quality, reducing noise, and supporting advanced features such as massive MIMO and beamforming. The findings underscore the feasibility of deploying hardware-efficient FIR filters in next-generation communication systems, thus contributing to the realization of high- performance 5G applications. Future research directions are suggested, aiming to investigate adaptive filtering techniques and the integration of emerging technologies to further elevate performance standards in dynamic wireless environments

Analysis and reduction of common-mode ground leakage current in transformerless PV inverters with rectified sine wave DC-link voltage

Abstract An essential requirement for transformerless photovoltaic (PV) inverters is the suppression of common-mode (CM) ground leakage currents. Transformerless PV inverters normally provide a voltage step-up capability to extend energy harvesting from PV arrays. In dual-mode time-sharing transformerless PV inverter topologies, a step-up (boost) stage operates alternatively with a step-down (buck) stage to create a rectified sine wave DC-link voltage, which is then unfolded to the grid by an H bridge. This study systematically analyzes and quantifies CM leakage current generation in topologies with rectified sine wave DC-link voltage. It highlights the role of the DC-link capacitor in CM current generation, explains why its capacitance needs to be low, and relates its value to the inverter output current amplitude and power factor. Then, it presents the mechanism of CM current generation by deriving analytical expressions for CM current root-mean-square values under different modes of inverter operation. This study also focuses on the design of the output filter and considers a split-inductor configuration that can reduce CM currents by up to 70%. The theoretical results are verified by simulations in MATLAB/Simulink and experiments involving a comprehensive laboratory setup.

Analysis of defect modes in a one-dimensional periodic parity-time symmetric optical waveguide network

Abstract We investigate the behavior of defect modes arising in a one-dimensional periodic parity-time (PT) symmetric optical waveguide network with defects. Utilizing the transfer matrix method, the generalized eigenfunction method, and the waveguide network equation, we investigate the unique optical properties of defect modes with exceptional point (EP) feature, including unidirectional and bidirectional transparency, as well as coherent perfect absorption-lasing (CPAL). The defect segments are introduced at the center of the structure, which is inherently PT-symmetric, ensuring that the overall system retains its PT symmetry. Our study demonstrates that the number, position, and nature of exceptional points can be adjusted by tuning the physical parameters of the defect segments. In particular, we identify optimal conditions for achieving CPAL frequencies. These results are significant for the development of all-optical devices and the design of broadband and narrowband optical filters.

Optical Asymmetric filter Using Graphene Plasmonic embedded in Photonic Crystal Fiber

This work exhibits simulation and design of a small-scale graphene plasmonic filter based photonic crystal fiber through finite element method investigation. Some cladding holes inside the PCF possess deposited 2-D graphene enabling the light transmission interaction which leads to surface plasmonic resonance (SPR). Improved optical filter performance results from this process because it enables better control and higher sensitivity and reduced signal loss so filters become optimal for use. A finite element method analyzes both polarization properties and spectral loss performance in the proposed structural design. The simulation evaluation was divided into two testing periods while changing the dimensions of PCF geometry. The investigation of first design components incorporated r = 6 and r = 5 while the second design components incorporated r = 6 and r = 7. The introduction of graphene materials into PCF rings comprises the two design models progressively from one to four rings. The design suffered maximum loss when four graphene rings were inserted in both designs. The absorption increases results in the creation of plasmonic polaritons. In the first design, when r = 6 and r = 5, the quasi-TE guided mode exhibits losses of -113000 dB/ mm for wavelengths λ = 1.14 μm. The quasi-TM guided mode exhibits losses of -109100 dB/ mm for wavelengths λ = 1.17 μm . In the second design, r = 6 and r = 7, the losses of the quasi-TE guided mode are -146800 dB/ mm for wavelengths λ = 1.16 μm. The quasi-TM guided mode exhibits losses of -146600 dB/mm at wavelengths λ = 1.2 μm.

Normalization of non-sinusoidality indicators of magnetoelectric generator under an autonomous mode of operation

The object of this study is a magnetoelectric generator with an excitation system based on permanent magnets and an additional magnetic system in the form of ferromagnetic shunts. This paper considers the task of non-sinusoidal voltage in a local electrical network with a magnetoelectric generator. This phenomenon negatively affects the operation of consumers and reduces the energy efficiency of the system. The work investigates the causes of harmonic distortion and proposes a method for reducing their impact. This helps ensure stable and high-quality operation of consumers in the electrical network. The generated voltage was studied in terms of non-sinusoidality for a magnetoelectric generator at different load levels in isolated operation. The non-compliance of the generated voltage with the requirements of the current standard in terms of the relative voltage of individual harmonics and the total harmonic distortion factor (THDU) was established. The dependences of the relative voltage of harmonics on the generator load level in the range from idle to nominal load were determined. The parameters of single-frequency resonant filters were calculated, which enable the normalization of the generated voltage according to the non-sinusoidality indicators under the conditions of isolated operation of the generator with a rated load. A feature of the results is the design of adaptive voltage non-sinusoidality filters that take into account the specificity of operation of the magnetoelectric generator in the local network. Analysis of the generator output voltage revealed that under an isolated operation mode, it is necessary to install filters of the 3rd, 5th, 9th, 21st, and 23rd harmonics in the entire generator load range. The absence of harmonic resonance phenomena is shown if filters with fixed parameters are used in the generator load range from idle to rated load

Narrow-band filter of Fabry-Pérot cavity over a wide spectrum range based on second-order resonant peak

Currently, it remains a challenge for micro-transmission filters based on diffractive nanostructures to achieve a balance among the spectral range, transmission efficiency, and color purity. While plasmonic metal metasurfaces of Fabry-Pérot (FP) cavities offer a wide spectral range, they are hindered by large full width at half maximum (FWHM) and low transmission efficiency; on the other hand, all-dielectric FP cavities exhibit small FWHM and high transmission efficiency but narrow spectral range. This study presents an innovative second-order FP cavity structure, wherein the introduction of a metal layer modifies the electromagnetic field distribution inside the cavity, leading to a shift in resonance modes. By suppressing odd-order resonant peaks and retaining even-order resonant peaks, this approach breaks the inherent link between FWHM and free spectral range (FSR), significantly expanding the spectral range while simultaneously reducing FWHM. Leveraging the optical absorption of silicon and the selective suppression effect of a platinum layer, a filter with FWHM ranging from 6 nm to 13 nm and an average transmission efficiency exceeding 70% is fabricated over a wide spectral range from 550 nm to 850 nm. This achieves a narrow linewidth and high color purity across a broad transmission spectrum. A detailed comparison between measurement data of samples and simulation results strongly validates the effectiveness and reliability of the proposed filter design.

Modelling and Optimization of Ceramic Water Filter Using Experimental Design

This study aimed to model and optimize the design of a ceramic water filter using an experimental design approach. The ceramic filter was fabricated from raw clay sourced from the Sè region, while rice husk and sawdust, served as the pore-forming material. The optimization process began with a screening of 11 factors using a screening design, followed by optimization through response surface methodology. The optimizations were performed using Minitab 17.1 software. The responses considered were water flow rate, turbidity, permanganate index, and absorbance at 254 nm. The results showed that filtration rates ranged from 0.01 mL/s to 3.44 mL/s, turbidity removal varied between 78% and 95%, permanganate index removal ranged from 75% to 96%, and E. coli removal was between 50% and 100%. The following conclusions were drawn from the experiment: (1) high flow rate values were achieved at higher hydraulic heads; (2) higher turbidity values occurred when the proportion of pore-forming material was low; (3) the proportion of pore-forming material and the applied hydraulic head jointly influenced the plasticity index; (4) proportions of pore-forming material between 20% and 25% tended to provide the highest reduction in the permanganate index; (5) E. coli removal was higher at lower proportions of pore-forming material, but the hydraulic head tended to reduce this removal. These findings offer new insights into the use of experimental design methodologies for the fabrication of ceramic water filters.

Overview and Recent Report of Integrated Filter Design Employing Frequency Dependent Negative Resistor (FDNR)

Filters are essential circuits for various signal processing circuits. One of the main methods of filter integration is to design an LC filter first as a prototype filter, and then simulate the function of the inductor with active components. Considering that the accuracy of elements implemented on a semiconductor chip is significantly lower than that of individual elements, this method, which uses a resistive doubly terminated LC ladder filter with low element sensitivity as the prototype, has been widely adopted. The Bruton Transformation is known as one of the methods to integrate the LC filter. The method avoids the use of inductor elements, which make integration difficult, and requires a component called a Frequency Dependent Negative Resistor (FDNR) . An FDNR is a negative resistance whose impedance is inversely proportional to the square of the frequency. Because the FDNR does not exist as a passive element, it is realized using an active block such as an operational amplifier. This paper provides an overview of the Bruton Transformation and the FDNR. The first half of this paper briefly describes the Bruton transformation and reviews the FDNRs proposed to date since the Bruton transformation was first presented. The second half of the paper presents the latest examples of filter integration methods using FDNR proposed by the authors.

Inversion feedforward control based on FIR filters for a 2-degree-of-freedom electro-hydraulic shaking table

Electro-hydraulic shaking tables (EHSTs) with multiple degrees-of-freedom (DOFs) are vital to large-scale structural-reliability experiments. The EHST control accuracy directly influences the qualitative and quantitative assessments of the reliability tests. Conventional three-variable control (TVC) fails to account for the coupling between the DOFs in multi-DOF EHSTs. Furthermore, TVC cannot adequately compensate for fluctuations in the acceleration frequency characteristics; thus, the waveform tracking accuracy is poor and suboptimal performance is achieved during high-precision vibration tests. An inversion feedforward control (IFC) based on the design of finite impulse response (FIR) filters is designed during this study to enhance the acceleration-waveform tracking accuracy in multi-DOF vibration tests. The iterative reweighted least squares (IRLS) algorithm is used to design the FIR filters, which are used to fit the impedance characteristics of a multi-DOF EHST. By using the designed FIR filters to filter the acceleration reference waveform, the coupling between the DOFs is compensated for, and this compensation reduces the fluctuations in the acceleration frequency characteristic and the influence of high-frequency noise. The IRLS algorithm is used to transform the passband and stopband filter design specifications into constrained least squares optimization problems. The frequency characteristics of the developed FIR filters enable high-precision fitting of both the impedance magnitude frequency and phase frequency characteristics within the bandwidth of the multi-DOF EHST system. Outside the bandwidth of the multi-DOF EHST system, the filters achieve high-decibel attenuation of the magnitude-frequency characteristic. Experimental acceleration frequency response and random waveform tracking results demonstrate that the filter-based IFC significantly enhances the random acceleration signal tracking accuracy for a multi-DOF EHST.

Design and Optimization of Broadband Optical Half-Band Filters Based on Cascaded MZIs

In optical communication systems, optical half-band filters are essential for efficient spectral separation, necessitating stringent performance criteria such as a wide spectral range, low insertion loss, and minimal crosstalk. This paper proposes a broadband optical half-band filter based on a cascaded Mach–Zehnder Interferometer (MZI) structure, which effectively improves spectral separation by enhancing flatness and sharpness at transition edges through the optimization of delay line length differences and phase compensation values. The results demonstrate that the proposed design achieves an insertion loss below 0.45 dB and inter-band crosstalk under −20.7 dB over a 40 nm bandwidth, with a roll-off of 2.2 dB/nm between 1517 nm and 1528 nm. The findings highlight the technical advantages of cascaded MZI structures in achieving high-precision spectral separation, offering a valuable reference for the development of future high-performance optical communication networks and integrated optical devices.

Design, fabrication and testing of microwave bandpass filter using metamaterial integrated rectangular waveguide

Abstract This paper presents RF/Microwave rectangular waveguide bandpass filter integrated with two-layer of periodical metamaterial SRR unit cell structure excited by proper EM wave boundary conditions. A properly constructed PCB-based metamaterial unitcell is integrated as a resonating circuit within a rectangular waveguide WR229. In order to achieve bandpass response, the metamaterial unit cell in the metallic waveguide of the designed RF bandpass filter is kept at λ g /4 spacing. Two open-ring resonators connected by a short stub are used to design the metamaterial unit-cell, which is fabricated on a Rogers 48350B substrate with a dielectric constant of ε r =3.48 and thickness of 1.52 mm. In addition, the metallic cavity generated with the CNC milling technology is zinc-coated to resist oxidation. The experimental results of the final prototype show good agreement with the overall wave modeling results. The proposed RF/microwave waveguide filters operated in the S-band frequency range; therefore, their applicability is recognized in RF sensing device for material characterization.

Study novel design of broadband edge filter as a smart window for energy saving

Abstract This study presents a new optimized broadband optical short wave pass (OSWP) edge filter designed for smart window applications to increase energy efficiency. The proposed filter has a dielectric structure with double layer composed of alternative high and low refractive index materials, which is designed to transmit the visible light and reflect the near-infrared (NIR) radiation. To achieve this functionality, we used the transfer matrix method (TMM) with the needle synthesis technique through the Essential Macleod software, which allows the accurate optimization of the thickness of the layer for maximum spectral control. The simulation results show that the filter maintains high visible light transmittance (>96%), while effectively blocks infrared wavelengths (750–1500 nm), with different performance as a function of the angle of incidence. The passive modulation properties of the filter provide seasonally adaptive thermal regulation, making it a viable solution for energy-saving smart window technologies. The results are relevant with the real world’s solar incident angles in Riyadh, Saudi Arabia.

Algorithm to Calculate PCB Stepped-Impedance Low-Pass Filters for Microwave Applications

In this paper, the design, simulation, and implementation of microwave stepped-impedance filters are carried out. This kind of filter can be built using a Printed Circuit Board (PCB) in the radiofrequency (RF) stage of a transmitter or receiver in radiocommunication systems. In the article, a computational tool is described in order to simplify the manufacturing process. The results section of the paper includes the software description in detail, the design of the tridimensional structure of the filter and computation of the patch that is located on the top layer in the PCB, the filter implementation, and the frequency response of the filter. The computational tool employed is a general-purpose software developed in Microsoft Visual Studio.

Dual-Broadband Topological Photonic Crystal Edge State Based on Liquid Crystal Tunability

The rapid advancements in optical communication and sensing technologies have significantly increased the demand for advanced tunable spectral systems. This study presents a dual-band terahertz transmission and manipulation approach by leveraging the topologically protected properties of valley-topological photonic crystal edge states. The designed structure facilitates the excitation of the K valley within the range of 0.851–0.934 THz and the K′ valley from 1.604 to 1.686 THz, while also demonstrating anomalous refraction and birefringence. The calculated emission angles, derived through momentum matching, enable transitions between single-wave and dual-wave emissions and allow for precise angle control. The introduction of the liquid crystal material NJU-LDn-4 enables continuous tuning of the dual-band spectral range under a varying electric field, broadening the operating frequency bands to the ranges of 0.757–0.996 THz and 1.426–1.798 THz, respectively. These findings suggest promising applications in tunable filter design, optical communication, photonic computing, optical sensing, and high-resolution imaging, particularly in novel optical devices requiring precise control over spectral characteristics and light propagation.

Innovative Wastewater Treatment Using 3D-Printed Clay Bricks Enhanced with Oyster Shell Powder: A Life Cycle Assessment

With growing global concerns over sustainable wastewater treatment, there is a pressing need for low-cost, eco-friendly filtration solutions. This study conducted a life cycle assessment (LCA) to evaluate the potential of improving slow sand filtration efficiency by integrating alternative materials like clay and oyster shell powder (OSP), while minimizing the environmental footprint. Additionally, the adaptability of three-dimensional (3D) printing was explored to incorporate these materials into innovative filter designs, assessing scalability for broader wastewater applications. Ten filter configurations, including a slow sand filter (SSF) enhanced with OSP (90:10) and 3D-printed clay–OSP bricks (ratios of 90:10, 85:15, 80:20), were assessed across three sourcing distances: local (in situ), regional (161 km), and distant (1609 km). The results showed that SSFs with OSP consistently delivered lower environmental impacts, reducing freshwater ecotoxicity, eutrophication, and human toxicity by up to 4% compared to conventional SSFs, particularly when transport was minimized. Among brick-based systems, single-brick columns offered the best balance of performance and impact, while three-brick columns had the highest environmental burden, largely due to the increased electricity use. Economic analysis reinforced the environmental findings: SSFs with OSP were the most cost-effective option, followed closely by SSFs, while brick-based systems were slightly more expensive, with costs rising sharply when sourcing distances exceeded 161 km. Overall, integrating OSP into SSFs offers an optimal balance of sustainability and affordability, while single-brick columns (90:10) present a promising alternative. Future research should further optimize material blends and design configurations to align with long-term environmental and economic goals.