Design Of Bandpass Filter Research Articles

SIW-DGS bandpass filter design for C band satellite communications

SIW-DGS bandpass filter design for C band satellite communications

Design of a modified hairpin bandpass filter using embedded radial stubs featuring ultrawide stopband

The analysis and design of a microstrip bandpass filter featuring an ultrawide stopband are presented and investigated in this paper. In this filter, single radial stubs are exploited in combination with a regular hairpin structure to achieve suppression of harmonic responses of the filter passband up to 10f0. The passband of the filter remains almost intact compared to the conventional hairpin filter. A 3rd-order BPF with a central frequency of 2 GHz and a bandwidth of 44% is designed and the simulation results are verified with the measurement results. The proposed filter shows more than 32 dB rejection from 3 GHz to 20 GHz in S21 and the measured passband insertion loss is 1.3 dB. The filter structure is simple, without the need for defected ground structures, multilayers, lumped elements, and even vias. The proposed filter can be in demand anywhere easy fabrication, low cost, ultrawide stopband together with a good rejection level are considered crucial.

Initial Rotor Position Estimation Method for Aircraft Three-Stage Starter/Generator Based on Self-Injected Harmonic Signal

In this article, an initial rotor position estimation method for an aircraft three-stage starter/generator (TSSG) based on self-injected harmonic signal (SIHS) is proposed. Different from the traditional method in which an external high-frequency signal is injected into the stator winding of the main generator (MG), the second harmonic voltage caused by the rotating rectifier in the ac excitation is regarded as the self-injected high-frequency signal into the rotor field winding of MG at standstill. The high-frequency response signals in the stator winding of MG are extracted by a designed bandpass filter (BPF), and the signals orthogonal to the response signals are generated by a cascaded all-pass filter (APF). Then, based on the obtained response signals and orthogonal signals containing rotor position information, a practical approach to estimate the initial rotor position is implemented, where the induced currents in the excitation establishment of MG are detected to identify the polarity of the initial rotor position angle. Finally, the feasibility and effectiveness of the proposed method are verified by simulation and experimental results.

Design of Multiband Bandpass Inline Topology Filters Using Compact Multicoupled Line Structures

This paper presents the synthesis and design of multiband bandpass filters (MBPFs) with in-line topology. The coupled-line coupling structures are employed to achieve multi-channel responses and compact footprint. Two different approaches are developed in this research to implement coupled-line MBPFs based on frequency transformation methods. The first synthesis method is based on the direct mapping technique. According to this method, a quad-band bandpass filter is theoretically synthesized and designed. The second proposed method is based on generlized ladder-type network analysis with frequency-invariant reactance elements (FIRs). It enables designing MBPFs with arbitrary number of passbands. To validate this method, a sext-band MBPFs is theoretically investigated, synthesized and designed in microstrip technology as well. Very good in-band filter performance and very good band-to-band isolation are observed for the proposed MBPFs. These results show that the proposed synthesis methods and structures are attractive solutions to design MBPFs with coupled line technology.

Time-varying filtering for nonstationary signal analysis of rotating machinery: Principle and applications

Rotating machinery vibration signals are composed of multiple time-varying frequency components under nonstationary conditions, and they usually overlap in the frequency domain. Effective extraction of these time-varying components is vital for rotating machinery fault diagnosis. This paper proposes a time-varying filtering (TVF) method for extraction of time-varying components. Its upper and lower cutoff frequencies are time-varying and independent. The TVF uses locally designed bandpass filters to achieve local filtering in the time domain, and exploits filtering with phase correction (FPC) and local filter lengths to ensure the phase and amplitude consistency of filtered signals. It cannot only extract time-varying mono-components but also separate time-varying frequency bands from highly nonstationary signals, for further time–frequency analysis: (1) fine time–frequency representations based on mono-components extraction, and (2) time-varying demodulation of time-varying frequency band of interests. The proposed method is illustrated and validated through numerical simulation, and signal analyses of typical rotating machines including a hydraulic turbine rotor, an aircraft engine rolling bearing, a multistage planetary gearbox, and a fixed shaft gearbox.

Compact Parallel Coupled Line Microstrip BPF Design for 5G Applications

A compact parallel coupled line microstrip bandpass filter (BPF) for sub-6 GHz fifth generation (5G) applications is designed operating between edge frequencies of 3.40 and 3.80 GHz. The design is designed and simulated by means of the Advanced Design System (ADS) software using the flame retardant-4 (FR-4) board as the substrate. The BPF design applies the insertion loss method (ILM) to generate a parallel coupled line filter structure that performs passband permission and unwanted noise attenuation below 3.40 GHz and above 3.80 GHz, respectively. Consistent and relevant performances in terms of matching impedance, return loss (S11), insertion loss (S21), voltage standing wave ratio (VSWR), far field radiation pattern, gain, directivity, and radiated efficiency promise the microstrip BPF design has a potential for sub-6 GHz 5G applications.

A Survey on Microstrip Single/Multiband Bandpass Filter for 5G Applications

For a long time, extensive research on microstrip bandpass filters has been documented to meet the standards of modern multiservice wireless communication systems. The multiband bandpass filters (BPF) are required for the receiver front end to function as a single device that caters to many bands at the same time. Planar bandpass filters are particularly promising because of their simplicity of manufacture using printed circuit technology, compactness, and low integration cost. Due to the need for high integration, low cost, and high-speed data transmission, the design and implementation of filters for fifth-generation (5G) mobile communication systems is difficult. This paper presents and discusses a detailed survey of existing research on microstrip singlemultiband bandpass filter designs for fifth-generation applications, with a focus on the latest advancements in this research and the difficulties that researchers face. Various designs and techniques were given. A detailed comparison of several design techniques is presented and discussed to offer researchers the benefits and drawbacks of each technique and design that may be of interest to a certain application. Recent microstrip single/multiband BPFs are included in the surveys, which use different design techniques and achieve varying performance for current and future fifth-generation applications.

Application of Compact Folded-Arms Square Open-Loop Resonator to Bandpass Filter Design

Folded-arms square open-loop resonator (FASOLR) is a variant of the conventional microstrip square open-loop resonator (SOLR) that facilitates further device size miniaturization by having the two arms of the conventional SOLR folded inwards. This paper highlights the benefits of this brand of compact SOLR by implementing a five-pole Chebyshev bandpass filter (BPF) using compact FASOLR. The test BPF is presented, with centre frequency of 2.2 GHz, fractional bandwidth of 10%, passband ripple of 0.04321 dB, and return loss of 20 dB. The design is implemented on a Rogers RT/Duroid 6010LM substrate with a dielectric constant of 10.7 and thickness of 1.27 mm. The filter device is manufactured and characterised, with the experimentation results being used to justify the simulation results. The presented measurement and electromagnetic (EM) simulation results demonstrate a good match. The EM simulation responses achieve a minimum insertion loss of 0.8 dB and a very good channel return loss of 22.6 dB. The measurement results, on the other hand, show a minimum insertion loss of 0.9 dB and a return loss of better than 19.2 dB. The filter component has a footprint of 36.08 mm by 6.74 mm (that is, 0.26 λg × 0.05 λg), with λg indicating the guided wavelength for the 50 Ohm microstrip line impedance at the centre frequency of the proposed fifth-order bandpass filter.

Y-type hexagonal ferrite-based band-pass filter with dual magnetic and electric field tunability

This work is on the design, fabrication and characterization of a hexagonal ferrite band-pass filter that can be tuned either with a magnetic field or an electric field. The filter operation is based on a straight-edge Y-type hexagonal ferrite resonator symmetrically coupled to the input and output microstrip transmission lines. The Zn2Yfilter demonstrated magnetic field tunability in the 8–12 GHz frequency range by applying an in-plane bias magnetic field H0 provided by a built-in permanent magnet. The insertion loss and 3 dB bandwidth within this band were 8.6 ± 0.4 dB and 350 ± 40 MHz, respectively. The electric field E tunability of the pass-band of the device was facilitated by the nonlinear magnetoelectric effect (NLME) in the ferrite. The E-tuning of the center frequency of the filter by (1150 ± 90) MHz was obtained for an input DC electric power of 200 mW. With efforts directed at a significant reduction in the insertion loss, the compact and power efficient magnetic and electric field tunable Zn2Y band-pass filter has the potential for use in novel reconfigurable RF/microwave devices and communication systems.

Design of dual-band BPFs with high selectivity

Abstract In this article, two dual-band microstrip bandpass filters (BPFs) with high selectivity and independently controllable passbands are designed based on three parallel-coupled lines (TPCLs). The first BPF proposed in this paper is achieved by employing a pair of folded F-type resonators (FFRs) and conventional TPCL structure. By adjusting the above parameters of each FFR, the center frequencies of the two passbands can be controlled easily. In the meantime, TPCL can enhance the coupling between the source and load, and introduce multiple transmission zeros (TZs), which can conduce to a higher selectivity. To obtain superior selectivity, the second BPF is designed based on a novel TPCL. The novel TPCL is based on the traditional one, which further enhances selectivity since transmission paths are doubled. In order to achieve miniaturization and enhance coupling, FFRs are folded. In addition, four transmission zeros (TZs) are generated to improve the selectivity of the two passbands. The measured results of the fabricated BPFs centered at 2.45/3.5 GHz agree well with the simulated ones, which validates the proposed design method.

Continuous-Time Analog Filters for Audio Edge Intelligence: Review on Circuit Designs [Feature

Edge audio devices can reduce data bandwidth requirements by pre-processing input speech on the device before transmission to the cloud. As edge devices are required to ensure always-on operation, their stringent power constraints pose several design challenges and force IC designers to look for solutions that use low standby power. One promising bio-inspired approach is to combine the continuous-time analog filter channels with a small memory footprint deep neural network that is trained on edge tasks such as keyword spotting, thereby allowing all blocks to be embedded in an IC. This paper reviews the historical background of the continuous-time analog filter circuits that have been used as feature extractors for current edge audio devices. Starting from the interpretation of a basic biquad filter as a two-integrator-loop topology, we introduce the progression in the design of second-order low-pass and band-pass filters ranging from OTA-based to source-follower-based architectures. We also derive and analyze the small-signal transfer function and discuss their usage in edge audio applications.

Arbitrary Termination Complex Impedances Tunable Bandpass Filter Using Single and Dual-Mode Resonators

This paper presents a design of microstrip line tunable bandpass filter (BPF) with a transmission zero (TZ) that can accommodate arbitrarily terminated input and output port impedances ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Z_s</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Z_L</i> ≠ 50 Ω). We extracted a new coupling matrix to design the proposed tunable BPF and presented intuitive circuit-level implementation using a single dc-bias controlled single and dual-mode resonators. The proposed tunable BPF integrates the function of tunable filter and matching network into a single circuit. To validate the design, three filter prototypes with different input and output port termination impedances (filter A: 50-to-50 Ω, filter B: 20-to-50 Ω, and filter C: (25+j10)-to-50 Ω) are manufactured and their performances were measured. The experimental results are consistent with the simulation showing that the passband frequency of the BPF can be tuned from 1.65 GHz to 2.08 GHz (23.06%) with the insertion loss variation from 3.40 dB to 4.69 dB. The proposed tunable BPFs achieved frequency selectivity characteristics by locating the TZ at a lower stopband. The proposed arbitrary terminated tunable BPF can allow direct connection between power amplifier (PA)/low noise amplifier (LNA) and antenna without extra matching networks, resulting in smaller circuit size and can enhance overall performance of RF front-end.

An ultra-narrow-band optical filter based on zero refractive index metamaterial

Owing to the photonic band gap effect and defect state effect, photonic metamaterials have received much attention in the design of narrow bandpass filters, which are the key devices of optical communication equipment such as wavelength division multiplexing devices. In this work, based on zero-index metamaterial (ZIM), a compact filter with both high peak transmission coefficient and ultra-narrow bandwidth is proposed. The photonic metamaterial with conical dispersion and Dirac-like point is achieved by optimizing the structure and material component parameters of dielectric rods with square lattice in air. It is demonstrated that a triply degenerate state can be realized at the Dirac-like point, which relates this metamaterial to a zero-index medium with effective permittivity and permeability equal to zero simultaneously. Electromagnetic (EM) wave can propagate without any phase delay at this frequency, and strong dispersion occurs in the adjacent frequency cone, leading to dramatic changes in optical properties. We introduce a ZIM into photonic metamaterial defect filter to compress the bandwidth to the realization of ultra-narrow bandpass filter. The ZIM is embedded into the resonant cavity of line defect filter, which is also composed of dielectric rods with square lattice in air. In order to increase the sensitivity of the phase change with frequency, the Dirac-like frequency is adjusted to match the resonant frequency of the filter. We study the transmission spectrum of the structure through the COMSOL Multiphysics simulation software, and find that the peak width at half-maximum of the filter decreases as the thickness of ZIM increases, and the peak transmittance is still high when bandwidth is greatly compressed. The zero phase delay inside the slab can be observed. Through field distribution analysis, the zero-phase delay and strong coupling characteristics of electromagnetic field are observed at peak frequency. The comparison with conventional photonic metamaterials filter is discussed. We believe that this work is helpful in investigating the realization of ultra-narrow bandpass filters.

Высокоселективный волноводный полосно-пропускающий фильтр с уровнем подавления помех более 120 dB

The design of a 10th-order waveguide bandpass filter with an additional inductive cross-coupling between non-adjacent resonators has been proposed and studied. An inductive coupling is formed by a U-shaped conductor structure with grounded ends that is formed in the filter cover. This method of cross-coupling organization ensures not only the temperature stability of the characteristics, but also the manufacturability of the structure. The high selectivity of the device is achieved by both the attenuation poles located near the passband, as well as the level of suppression in the stopbands, exceeding 120 dB. The passband loss of the fabricated filter is ~0.8 dB at its central frequency f0 = 18.2 GHz and relative bandwidth Δf / f0 = 1.5%. The small dimensions (135×30×10 mm3) and the weight of about 200 g of the device, with simultaneously high electrical characteristics show the promise of its use, for example, in on-board and ground-based space communication systems.

A high-selectivity waveguide bandpass filter with interference suppression by more than 120 dB in rejection band

The design of a 10th-order waveguide bandpass filter with an additional inductive cross-coupling between non-adjacent resonators has been proposed and studied. An inductive coupling is formed by a U-shaped conductor structure with grounded ends that is formed in the filter cover. This method of cross-coupling organization ensures not only the temperature stability of the characteristics, but also the manufacturability of the structure. The high selectivity of the device is achieved by both the attenuation poles located near the passband, as well as the level of suppression in the stopbands, exceeding 120 dB. The passband loss of the fabricated filter is ~ 0.8 dB at its central frequency f0=18.2 GHz and relative bandwidth Delta f/f0=1.5%. The small dimensions (135x 30x 10 mm) and the weight of about 200 g of the device, with simultaneously high electrical characteristics show the promise of its use, for example, in on-board and ground-based space communication systems Keywords: bandpass filter, waveguide, resonator, cross-coupling.

Compact broadband bandpass filter with wide stopband based on halberd-shaped spoof surface plasmon polariton

In this paper, a compact broadband bandpass filter with wide out-of-band rejection characteristics based on halberd-shaped spoof surface plasmon polariton (SSPP) is proposed. The filtering structure is achieved by etching a periodic halberd-shaped groove at the bottom of the substrate and a microstrip-to-slot line transition with a crescent-shaped patch at the top. Compared with the traditional dumbbell-shaped SSPP, the halberd-shaped SSPP has good slow-wave property, and the designed bandpass filter based on halberd-shaped SSPP can achieve a more compact size. The upper cutoff frequency and lower cutoff frequency of the passband can be adjusted by regulating the SSPP structure and the transition structure from microstrip-to-slot line, respectively. The simulation results show that the center frequency of broadband bandpass filter is 2.85 GHz, with the relative bandwidth of 130%, and the return loss in the passband is better than –10 dB, and the extreme strong out-of-band rejection of –40 dB from 5.6 GHz to 20.0 GHz. The size of the broadband bandpass filter is compact, only 1.08&lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;g &lt;/sub&gt;× 0.39&lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;g&lt;/sub&gt;, where &lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;g&lt;/sub&gt; is the wavelength at the center frequency. In order to verify the effectiveness of the wideband bandpass filter, the traditional printed circuit board technology is used to fabricate the wideband bandpass filter. The measurement results are in good agreement with the simulation results, verifying the feasibility of the design. The proposed broadband bandpass filter shows promising prospects for developing SSPP functional devices and circuits at microwave frequencies.

METHOD OF DESIGNING ANTENNAS BY SYNTHESIS OF A BAND FILTER

A novel antenna design technique is proposed, which offers bandwidth enhancement up to the limits defined by element radiation efficiency. The employed technique is referred as frequency pulling (FP) as it mimics the insertion loss design methodology of bandpass filters. This is essentially a wideband matching approach pushing the antenna efficiency to the limits set up by radiation efficiency. There are three options towards this trend: (1) first to enhance a single element bandwidth (compact element) exploiting its possibly multiple symmetrical feeding points as distinct resonator ports, (2) frequency pulled array as to design a small antenna array (less than about 10 elements) where eachelement acts as a resonator and (3) second order frequency-pulled array as to build a small array using compact elements of category (1). Similar to the band-pass filter design, all antennas or distinct-port circuits resonate at the same resonant frequency when isolated, cascading two or more of them; FP yields to multiple-overlapping successive resonances in their overall response. Although the proposed technique is general within this first effort, it is applied to simple patch antenna elements exhibiting multiple symmetrical feeding points, namely two-for rectangular, four-for square and five-for pentagonal. The third option is applied to an array of three compact 4-feeding point square elements offering triple bandwidth with respect to the already wideband single element. However, this is achieved at the expense of a significant beam squint. Thus, in general, these wideband compact elements should be used within a classical array design. Further bandwidth enhancement using FP to antenna elements with inherent multiple resonances as patches with slots or truncated edges constitutes our next task. Their inherent wider bandwidth in radiation efficiency is expected to allow multiply higher bandwidths when exploited with our FP technique.

Design of miniaturized single and dual-band bandpass filters using diamond-shaped coupled line resonator for next-generation wireless systems

AbstractThis paper presents a multi-mode resonator (MMR) for next-generation wireless systems that achieves single and dual-band bandpass filter (BPF) responses using a split-ring dual-path structure. The proposed BPF design is realized by employing two pairs of parallel couple lines and two symmetrical step-impedance open-circuited stubs (SIOCS). SIOCS are used to improve selectivity and increase the number of transmission zeros/poles. The proposed single-band BPF exhibits an ultra-wideband (UWB) response having a center frequency of 7.5 GHz, a minimum insertion loss of less than 0.48 dB, and a maximum return loss of 25.35 dB. The proposed UWB BPF has a stopband suppression of 39.34 dB up to 18 GHz and a 3 dB fractional bandwidth of 48.23%. Moreover, a dual-band BPF has been accomplished by utilizing the same architecture while slightly changing the MMR structure and adding more coupling. The center frequency (bandwidth) of the dual broadband BPF is 7.40 GHz (2.40 GHz) and 14.15 GHz (1.7 GHz), respectively. The measured minimum insertion loss is less than 0.23 dB and a return loss of less than 16.8 dB with 3 dB FBWs of 32.4 and 12.1%. Finally, two prototypes are fabricated to validate the proposed characteristics. The BPF's simulated and measured results are in good agreement.

Design and Optimization of an S-Band MEMS Bandpass Filter Based on Aggressive Space Mapping.

Aggressive space mapping (ASM) is a common filter simulation and debugging method. It plays an important role in the field of microwave device design. This paper introduces ASM and presents the design and fabrication of a compact fifth-order microstrip interdigital filter with a center frequency of 2.5 GHz and a relative bandwidth of 10% using ASM. The filter used a double-layer silicon substrate structure and stepped impedance resonators (SIRs) and was optimized by ASM. After five iterations, the filter achieved the design specification, which greatly improves the efficiency of the filter design compared with the traditional method. It was fabricated on high-resistance silicon wafers by micro-electro-mechanical systems (MEMSs) technology, and the final size of the chip is 9.5 mm × 7.6 mm × 0.8 mm. The measurement results show that the characteristics of the filter are similar to the simulation results, which also shows the efficiency and precision of the ASM algorithm.

Stopband enhanced patch‐type filter using common‐mode feeding method based on multilayer liquid crystal polymer lamination technology

AbstractIn this study, a new common‐mode feeding approach to the 2‐D square patch resonator is proposed and applied in the design of bandpass filter (BPF) with wideband harmonic suppression. Different from the conventional single‐point feeding structure, the proposed one has two physical feeding points on the patch. It is indicated from the electric field distributions that the presented feeding method can not only support the excitation of the desired fundamental TM01 mode, but also enable the rejection of high‐order modes by selecting proper feeding positions. For demonstration, a second‐order BPF centred at 4.0 GHz with wide stopband suppression has been implemented by using multilayer liquid crystal polymer circuit technology. Moreover, benefitting from mixed‐coupling, a transmission zero is introduced to improve the filtering selectivity. Measured and simulated results are in good agreement with each other, validating the proposed feeding concept.