Ultra-wideband Bandpass Filter Research Articles

A Wide Stopband Dual-notched Bands UWB Filter Based on A Novel Composite Right/left Handed Transmission Line

Background:: As one of the key components of ultra-wideband (UWB) system, UWB filter has important research significance. However, the current UWB filter still has the problem of a narrow stopband and cannot suppress the interference signals in the passband Objective:: In this paper, a novel UWB bandpass filter is proposed, which has wide stopband characteristics and good out-of-band rejection performance and implements a notch function for the WLAN band and the X satellite communication band in the passband to improve the antiinterference performance. Method:: The filter adopts a novel composite right/left handed transmission line (CRLH-TL) structure to realize the passband characteristics with low insertion loss (< 0.8dB). The anticoupled line structures generate two transmission zeros (TZs) in the upper stopband, which improves the upper stopband performance of the filter. The short circuit step impedance resonators (SIRs) and the asymmetric coupling structure generate a notched band in the passband respectively. Results:: The simulated and measured results show that the 3dB passband range is 3.4-11.0 GHz, the out-of-band rejection is more than 20 dB in the stopband range of 12.8-28 GHz, and the dualnotched bands are located at 5.86 GHz and 8.0 GHz respectively. The measured results are basically consistent with the simulated results. Conclusion:: Compared with the existing filters, the proposed filter has outstanding advantages and has a wide range of application prospects in the field of indoor UWB positioning system.

Design of a superconducting UWB bandpass filter with tunable notch band

By studying the principles of ultra-wideband (UWB) and band-stop, a novel band-pass filter with adjustable band-stop characteristics is proposed. The filter achieves 3.1-10.6 GHz UWB bandpass characteristics through an improved multi-mode resonator. An L-shape λ/2 notch resonator loaded with a 2-bit reconfigurable interdigital capacitor (IDC) array is coupled to the multiple-mode resonator and generates a tunable notch band to reject any undesired signal that may interfere with the UWB passband. By connecting the IDC to the ground or not, the capacitance of each IDC and the corresponding notch frequency can be adjusted. After design and optimization, the final size of the superconducting filter is 20.0 mm × 6.9 mm, and the test results and simulation results are highly consistent.

A Design Method and Application of Meta-Surface-Based Arbitrary Passband Filter for Terahertz Communication.

A meta-surface-based arbitrary bandwidth filter realization method for terahertz (THz) future communications is presented. The approach involves integrating a meta-surface-based bandstop filter into an ultra-wideband (UWB) bandpass filter and adjusting the operating frequency range of the meta-surface bandstop filter to realize the design of arbitrary bandwidth filters. It effectively addresses the complexity of designing traditional arbitrary bandwidth filters and the challenges in achieving impedance matching. To underscore its practicality, the paper employs silicon substrate integrated gap waveguide (SSIGW) and this method to craft a THz filter. To begin, design equations for electromagnetic band gap (EBG) structures were developed in accordance with the requirements of through-silicon via (TSV) and applied to the design of the SSIGW. Subsequently, this article employs equivalent transmission line models and equivalent circuits to conduct theoretical analyses for both the UWB passband and the meta-surface stopband portions. The proposed THz filter boasts a center frequency of 0.151 THz, a relative bandwidth of 6.9%, insertion loss below 0.68 dB, and stopbands exceeding 20 GHz in both upper and lower ranges. The in-band group delay is 0.119 ± 0.048 ns. Compared to reported THz filters, the SSIGW filter boasts advantages such as low loss and minimal delay, making it even more suitable for future wireless communication.

Quasi-elliptic band pass filter using resonators based on coupling theory for ultra-wide band applications

PurposeThis paper aims to present the simulation, fabrication and testing of a novel ultra-wide band (UWB) band-pass filters (BPFs) with better transmission and rejection characteristics on a low-loss Taconic substrate and analyze using the coupled theory of resonators for UWB range covering L, S, C and X bands for radars, global positioning system (GPS) and satellite communication applications.Design/methodology/approachThe filter is designed with a bent coupled transmission line on the top copper layer. Defected ground structures (DGSs) like complementary split ring resonators (CSRRs), V-shaped resonators, rectangular slots and quad circle slots (positioned inwards and outwards) are etched in the ground layer of the filter. The circular orientation of V-shaped resonators adds compactness when linearly placed. By arranging the quad circle slots outwards and inwards at the corner and core of the ground plane, respectively, two filters (Filters I and II) are designed, fabricated and measured. These two filters feature a quasi-elliptic response with transmission zeros (TZs) on either side of the bandpass response, making it highly selective and reflection poles (RPs), resulting in a low-loss filter response. The transmission line model and coupled line theory are implemented to analyze the proposed filters.FindingsTwo filters by placing the quad circle slots outwards (Filter I) and inwards (Filter II) were designed, fabricated and tested. The fabricated model (Filter I) provides transmission with a maximum insertion loss of 2.65 dB from 1.5 GHz to 9.2 GHz. Four TZs and five RPs are observed in the frequency response. The lower and upper stopband band width (BW) of the measured Filter I are 1.2 GHz and 5.5 GHz of upper stopband BW with rejection level greater than 10 dB, respectively. Filter II (inward quad circle slots) operates from 1.4 GHz to 9.05 GHz with 1.65 dB maximum insertion loss inside the passband with four TZs and four RPs, which, in turn, enhances the filter characteristics in terms of selectivity, flatness and stopband. Moreover, 1 GHz BW of lower and upper stopbands are observed. Thus, the fabricated filters (Filters I and II) are therefore evaluated, and the outcomes show good agreement with the electromagnetic simulation response.Research limitations/implicationsThe limitation of this work is the back radiation caused by DGS, which can be eradicated by placing the filter in the cavity and retaining its performance.Practical implicationsThe proposed UWB BPFs with novel resonators find their role in the UWB range covering L, S, C and X bands for radars, GPS and satellite communication applications.Originality/valueTo the best of the authors’ knowledge, for the first time, the authors develop a compact UWB BPFs (Filters I and II) with BW greater than 7.5 GHz by combining reformed coupled lines and DGS resonators (CSRRs, V-shaped resonators [modified hairpin resonators], rectangular slots and quad circle slots [inwards and outwards]) for radars, GPS and satellite communication applications.

Reflectionless Ultra-Wideband bandpass filter based on suspended coplanar waveguide-microstrip broadside coupling

In this paper, a reflectionless ultra-wideband (UWB) bandpass filter (BPF) is proposed based on complementary diplexer, which is composed of a BPF and two bandstop filters (BSFs). BSFs are added to the two ports of the BPF as the auxiliary channels. At the same time, resistors are connected to the terminals of the BSFs to absorb stopband signals of the BPF reflected back to the source. Among them, the BPF consists of four broadside coupled lines of suspended coplanar waveguide-microstrip (SCPW-MS), and the BSF consists of a coupled line and an open-circuited stub. The two complement each other to form the reflectionless UWB BPF. As an example, a reflectionless UWB BPF with center frequency of 5.3 GHz, fractional bandwidth (FBW) of 113 %, and minimum insertion loss of 0.5 dB has been successfully developed. The fabricated device has the advantages of low loss, UWB and self-packaging.

A Miniaturized UWB Bandpass Filter Employing Multi-Stub-Loaded Short-Circuited Stepped Impedance Ring Resonator

This article presents a novel microstrip line topology implementation of an ultra-wideband (UWB) bandpass filter. The proposed topology is a short-circuited stepped-impedance ring resonator with an open-circuit stub and a short-circuit stub loaded at the central vertical position of the low impedance of this resonator, respectively. Within the UWB spectrum, five modes are allocated under weak coupling, and to increase filter selectivity, two transmission zeros are added. It is possible to extend the upper stopband and provide sufficient external coupling by utilizing interdigital-coupled lines. To demonstrate the design theory, a prototype is designed and manufactured on a 0.8 mm thick substrate of the affordable F4B-2, and its performance is verified. Measurements show a 3-dB bandwidth span from 2.8 to 9.5 GHz, insertion loss of 0.36 dB, and return loss better than 13 dB.

A planar BPF for UWB communication systems with single/multiple interference rejection bands

Abstract The design and development of a microstrip-based planar ultra-wideband (UWB) bandpass filter (BPF) with single/multiple interference rejection capability is presented. The proposed BPF structure is developed based on the broadside coupled mechanism of microstrip/coplanar waveguide (CPW). The BPF has microstrips and short-circuited CPW capacitively coupled through the substrate. The basic frequency response generated from this geometry covers the necessary UWB spectrum (3.1–10.6 GHz) and possesses appreciable characteristics due to dual transmission zeros at either passband boundary. Multiple resonators are embedded in the basic BPF structure to develop passband notches to circumvent unnecessary interferences. A low-pass filter is later integrated into geometry to extend the upper stopband. The proposed structure is compact and covers an area of only 14 × 11.4 mm2.

Dual UWB bandpass filter with highly band-to-band rejection using stepped impedance stub-loaded resonators for WBAN health-care applications

Abstract With the rapid development of communication technology, the researches of multi-band filtering circuits have become more and more important. Multimode resonator (MMR) is one of the vital methods to provide multi-resonant modes within a single design. In this paper, a dual-band ultra-wideband bandpass filter (UWB-BPF) using stepped impedance stub-loaded resonators (SI-SLR) is presented. The main advantage of using SI-SLR is to have better performance with multimode behavior and more parameters to control resonant modes. SI-SLR combines the advantages of SIR and SLR structures, which gives a compact, high-performance multiband filter. The proposed filter design has compact size, sharp and flat response with low insertion loss (IL), low return loss (RL), and high band-to-band rejection. The filter is designed for UWB communication in wireless body area networks and fabricated on Arlon substrate with relative permittivity ${\varepsilon_{\textrm{r}}} = 3.25$ , thickness $0.8\;{\textrm{mm}}$ . The resulted dual-bands are centered at $4{\textrm{ GHz}}$ and $8.3{\textrm{ GHz}}$ with fractional bandwidths $37{\textrm{% }}$ and $48{\textrm{%}}$ . The simulation was carried out using CST Microwave Studio. The filter provides good passband performances, with IL 0.49 dB and 0.31 dB at the center frequency of lower and higher bands, respectively. The band-to-band 40 dB rejection is realized by adding circular spiral at the input/output of the filter.

A Novel Synthesis of Quasi-Chebyshev Ultra-Wideband Bandpass Filter Using Nth Order Stub Loaded Coupled-Line Resonator.

This paper presents a novel synthesis of a quasi-Chebyshev Nth order stub-loaded coupled-line ultra-wideband bandpass filter. A unit element of a proposed filter topology consists of two short-circuited stubs loaded at the edges of coupled lines. A distributed equivalent circuit model of a proposed topology is extracted and used to acquire a generalized filtering function. The extracted filtering function is of rational form. The denominator of the filtering function causes a mismatch with Chebyshev type-I polynomials. For conventional narrowband filters, the denominator term can be neglected because of the close vicinity of band-edge frequencies; however, for the ultra-wideband filter response, the factor in the denominator cannot be neglected and hence requires a new mathematical procedure to compensate for the effect of the frequency-dependent term in the denominator. The electrical parameters are calculated using the proposed synthesis and used to design an ideal filter topology on ADS. To validate the proposed design procedure, fabrication is performed on a high-frequency substrate. The proposed filter is miniaturized in size and has good out-of-band performance. The simulated and measured results provide good agreement.

A UWB bandpass filter based on elliptical open stub-loaded resonator and dumbbell-sided cross-circle DGS

An Ultra-wideband (UWB) bandpass filter (BPF) based on an elliptical open stub-loaded resonator (EOSLR) and dumbbell-sided cross-circle (DSCC) defected ground structure (DGS) is proposed in this paper. The measured results show that the 3 dB bandwidth of the filter is 3.49 ∼ 11.04 GHz, the skirt factor (S.F) is 0.844, the upper stopband rejection is greater than 20 d B at 11.70 ∼ 26.80 GHz, and the stopband width is 15.1 GHz. The proposed filter has the advantages of high selectivity and extremely broad upper stopband and it can be applied in UWB Wireless communication system.

A miniaturized UWB bandpass filter with tunable cut-off frequencies employing rectangular open-loop defected ground structure

AbstractThis article presents a compact rectangular impedance resonator (RIR)–based ultra-wideband bandpass filter with an improved reflection coefficient within the passband and controllable cut-off frequencies. The proposed filter consists of anti-parallel coupled RIR coupled with rectangular open-loop defected ground structure (ROL-DGS) etched on the ground plane. The ROL-DGS ensures better in-band and out-off-band characteristics with reduced size due to its high Q-factor. The short- and open-circuit stubs control the lower (fCL) and upper (fCU) 3-dB cut-off frequencies, respectively, by originating transmission zeros independently with the help of variations in design parameters. As a result, the filter having a compact size of 0.216λCL × 0.176λCL is achieved, where λCL is the corresponding guided wavelength at the lower cut-off frequency fCL of 2.95 GHz. Further, an equivalent circuit is also modeled to explain the working of the proposed filter, and equivalent lumped parameters were extracted. Simulated results reveal that the reported filter passes the frequencies effectively within 2.95–11.44 GHz with fractional bandwidth of 117.9%. The simulated insertion loss values within the passband are less than 1.17 dB, and the reflection coefficient is better than −19.6 dB. Further, the proposed filter is fabricated, and it was found that the measured and simulation results are in well agreement.

Multifunctional Organic-Inorganic Hybrid Perovskite Microcrystalline Engineering and Electromagnetic Response Switching Multi-Band Devices.

High-efficiency electromagnetic (EM) functional materials are the core building block of high-performance EM absorbers and devices, and they are indispensable in various fields ranging from industrial manufacture to daily life, or even from national defense security to space exploration. Searching for high-efficiency EM functional materials and realizing high-performance EM devices remaingreat challenges. Herein, a simple solution-process is developed to rapidly grow gram-scale organic-inorganic (MAPbX3 , X=Cl, Br, I) perovskite microcrystals. They exhibit excellent EM response in multi bands covering microwaves, visible light, and X-rays. Among them, outstanding microwave absorption performance with multiple absorption bands can be achieved, and their intrinsic EM properties can be tuned by adjusting polar group. An ultra-wideband bandpass filter with high suppression level of -71.8dB in the stopband in the GHz band, self-powered photodetectors with tunable broadband or narrowband photoresponse in the visible-light band, and a self-powered X-ray detector with high sensitivity of 3560µCGyair -1 cm-2 in the X-ray band are designed and realized by precisely regulating the physical features of perovskite and designing a novel planar device structure. These findings open a door toward developing high-efficiency EM functional materials for realizing high-performance EM absorbers and devices.

A compact, flexible and transparent UWB bandpass filter with silver nanowires

The advent of ultra-wide band (UWB) technology has made bandpass filters omnipresent. Current approaches to designing bandpass filters cannot provide transparent and flexible bandpass filters to meet their increasing demands for various applications. In this new work, a flexible and transparent UWB bandpass filter with silver nanowires printed on flexible polyethylene terephthalate (PET) substrates is designed. The filter structure is formed by connecting three pairs of open-circuited rectangular stubs. Proper coupling of these stubs is used to obtain the desired UWB passband. The proposed design operating from 1.05 to 10.75 GHz with an extremely wide stopband up to 50 GHz and a rejection level of 11.4 dB is demonstrated in the measured results. Furthermore, it was observed that the measured results matched well with the simulated results. These improved results indicate that our design strategy will provide a way to design highly efficient flexible UWB filters. This flexible filter may serve as a potential candidate for increasing the flexibility of indoor electronic applications.

Design of a Compact Ultra-Wideband Microstrip Bandpass Filter

A compact ultra-wideband bandpass filter based on a multilayer printed circuit board (MPCB) structure is proposed in this paper. RO4450F prepreg is used to bond three RO4350B dielectric substrates with different thicknesses in the MPCB structure. The upper surfaces of the three dielectric substrates are respectively provided with copper-coated structures with different patterns. The blind holes and the defected ground structure (DGS) are added to the MPCB of an ultra-wideband bandpass filter. Two groups of loaded quarter-wavelength terminal-open stubs introduce two transmission zeros, which improves the roll-off rates and stopband characteristics, while simple DGS composed of rectangular slots introduces two resonance points in the passband to improve the return loss. Simulation and measurement are consistent. The insertion loss at the center frequency of 12.795 GHz is 0.58 dB and the fractional bandwidth of 3 dB is 40.33% from 10.215 GHz to 15.375 GHz. This bandpass filter can be widely used in wireless and satellite communication.

Design of double-notch UWB filter with upper stopband characteristics based on ACPW-DGS.

In this manuscript, a compact (size only 9.8mm*9.8mm) Ultra Wide Band (UWB) bandpass filter with a new structure is proposed, which can be used in the UWB wireless communication band authorized by the FCC. The top plane is composed of a pair of back-to-back microstrip lines, and the ground plane structure is based on an asymmetric coplanar waveguide-defect ground structure (ACPW-DGS). UWB is formed by the vertical electromagnetic coupling of the top plane and the ground plane. On this basis, split ring resonator (SRR) and C type resonator (CTR) are utilized to place double notch bands. A novel third order nested C-type resonator (TONCTR) is obtained by performing CTR, which can further optimize the upper stopband while ensuring double notch bands. The filter can be used for filtering within the UWB system, and it can also avoid the amateur radio band (9.2 -10.3GHz) and the X-band satellite link band (9.6-12.3GHz) on UWB communication systems. Finally, the measured results from the fabricated prototype are basically consistent with the simulation results.

Design, Modeling, and Implementation of Dual Notched UWB Bandpass Filter Employing Rectangular Stubs and Embedded L-Shaped Structure

Targeting the range defined by the FCC (Federal Communication Commission) in 2002 for ultra-passband bandpass filters, i.e., 3.1 to 10.6 GHz, this article presents a simple compact multipoles ultra-wideband bandpass filter (range starting from 2.9 GHz and end at 11.5 GHz with central frequency 7.2 GHz) using parallel coupled microstrip line and multimode resonator with controllable double narrow notched bands at 3.5 GHz and 7.5 GHz by embedded a spur line structure and rectangular stub resonator coupled to the middle section of the multimode resonator to eliminate the interference with the existing radio signals falls in the range of 3.1 to 10.6 GHz, respectively. After optimization of the proposed filter, some attractive features were obtained, i.e., a compact size 21 mm × 5.2 mm, simple topology, good reflection coefficient lower than −18 dB, good passband transmission coefficient –1.1 dB over the entire fractional bandwidth of about 119.4%, and four transmission poles at 3.4 GHz, 4.6 GHz, 6.5 GHz, and 10 GHz, respectively, can be seen which improves the performance of the filter. Finally, the fabricated filter was tested, and the results obtained demonstrated an excellent agreement.

Highly compact UWB-BPF with a wide notch-band using a rectangular ring structure and two Y-shaped open stub resonators

A miniaturized ultra-wideband bandpass filter (UWB-BPF) with a high rejection notched band is proposed in this article. It is composed of a rectangular ring with two grounded vias, a microstrip line with two open radial stubs, a pair of interdigital feedlines with two lumped capacitors and two open-loaded Y-shaped stub resonators (YSSR), as well as a defected ground structure (DGS). This filter was simulated and fabricated by using a practical printed circuit board (PCB) process with the substrate of FR4. The measurement results agree well with the simulation data. The measured 3-dB passbands cover 2.73–4.36 and 6.82–11.78 GHz, the in-band insertion loss is less than 1.13 dB except at the edges of the bands, and the return loss is better than 10 dB. It is found that the filter’s lower and upper transmission zeros occur at 0.8 and 13.95 GHz with the magnitudes of −87.2 and −45.6 dB, respectively. This makes the filter exhibit high selectivity with the steep skirt characteristics. It is also worth noting that the proposed filter possesses a wide 10-dB notch band ranging from 4.87 to 6.93 GHz with the highest rejection of 46.3 dB at 5.9 GHz. This feature can effectively and simultaneously inhibit the unwanted signals coming from the C-band 5G mobile communication, 5-GHz WiFi, WLAN, and 6-GHz satellite systems. Furthermore, the presented filter is highly compact with the dimensions of 13.2 mm × 11.8 mm and has a very wide upper stopband spanning from 13.4 to 28 GHz with rejection of 20 dB or higher.

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.

A Compact Ultra-Wideband Multimode Bandpass Filter With Sharp-Rejection Using Stepped Impedance Open Stub and Series Transformers

This brief presents the analysis and design of an ultra-wideband bandpass filter (UWBPF) with four transmission zeros and seven poles. The UWBPF model consists of series transformers, coupled lines, and a shunt-stepped impedance open stub. The even-odd mode analysis method and scattering parameters theory are used to extract the closed-form equations for transmission zeros and poles of the proposed UWBPF. For validation, a prototype with a center frequency of 2.49 GHz is designed, simulated, and tested. The measured 3 dB fractional bandwidth is 103.2%, and the fabricated prototype occupies an area of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.165\lambda _{g}^{2}$ </tex-math></inline-formula> . The circuit, full-wave simulated, and experimental results are in a good match.

A surface-to-surface transition based UWB bandpass filter with triple in-band notches

A Compact Ultra-Wideband (UWB) bandpass filter (BPF) designed using the surface-to-surface transition mechanism and with triple passband transmission zeros (TZs) is proposed. The geometry of basic structure consists of two microstrip lines placed facing each other on the top plane coupled with a short circuited co-planar waveguide (CPW) in the bottom plane. This basic architecture develops a UWB response with two transmission zeros (TZs) at lower/higher passband edges, which exhibits good frequency characteristics. Later, complementary folded split ring resonator (CSRR), split ring resonators (SRRs) and folded split ring resonators (FSRRs) are appended to the basic architecture to generate triple passband notches so as to circumvent interferences. A hardware prototype is finally developed and its response tested against the simulated data. The triple-notched BPF is compact covering a physical area of only 14 × 11.4 mm2.