Ultra-wideband Filter Research Articles

Optimal Design of a Compact Filter for UWB Applications Using an Improved Particle Swarm Optimization

This paper proposes an improved particle swarm optimization (PSO) process to design a high-performance compact ultrawideband (UWB) filter. The filter consists of one-cell composite right- and left-handed-transmission line (CRLH-TL) resonator, a stepped impedance (SI), and two spurlines. The one-cell CRLH-TL resonator has compact size but performs wide passband filtering. One SI and two spurlines are employed to reject both the harmonics outside the UWB and the wireless local area network (WLAN) (5.15–5.825 GHz) band. The improved PSO consists of the conventional PSO with the sensitivity analysis, and the process for checking the ripple. The improved PSO suppresses the ripple and accelerates the optimization. During the improved PSO, the objective function converges from the 116th iteration. In addition, the characteristic of the filter is optimized to get acceptable results. The proposed filter has the overall size of $14 \times 15$ mm2 ( $0.63\lambda _{g} \times 0.53\lambda _{g})$ only, a 105% bandwidth for a return loss >10 dB, a flat insertion loss $11.5\sim 22$ GHz and WLAN band. In particular, the ripple in the passband is minimized significantly by the improved PSO.

Design of UWB microstrip bandpass filter using stub‐loaded quintuple‐mode resonator

ABSTRACTDesign of a novel ultra‐wideband (UWB) microstrip bandpass filter is presented by using a square loop quintuple‐mode resonator (QMR) having open‐circuited stubs. The proposed resonator has five resonant modes in UWB band range and is coupled to Input/Output (IO) ports by parallel‐coupled feed lines. The first three resonance modes are resulted from the stub loaded square loop resonator, whereas the remaining two modes can be formed by means of the coupling between the open‐circuited stubs and the resonator. The designed UWB filter has totally seven poles including two poles resulting from the nature of the coupling sections and five poles from the QMR. Theoretical analysis of the resonator is realized by defining the equivalent circuit model. Coupling scheme and coupling matrix of the designed filter are also extracted to clarify the filter topology. In addition, two patch perturbation elements are used to control the in‐band return loss levels. A seven pole UWB bandpass filter is designed, analyzed, and fabricated. Measurement results show a good agreement with the predicted results. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:662–666, 2016

A Design of Ultra-wideband Filter with Band-notched Characteristic Based on Left - Handed Materials

Based on the concept of left-handed material (LHM), a novel ultra-wideband (UWB) planar filter with negative permittivity and permeability was designed and proposed in this paper. By etching a cross-coupled structure on the surface of substrate , the filter achieved a frequency pass band of 2.86 - 11.22 GHz, which meets requirement of the UWB applications. Moreover, a notch frequency band of 7.26 - 9.13 GHz also achieved simply by increasing the length of the left hand cross side structure. HFSS software was used to design and optimise the filter .The subtract of the filter is with a relative dielectric constant of 2.55 and the overall size of the filter is 7.6×16 × 0.8 mm 3 .

An ultra-wideband filter based on right/left handed transmission line

This paper will introduce the new ultra-wideband filter with right/left handed transmission line structure design. Further use the microstrip line and coplanar waveguide combination to simplify the design, reduce the size. Simulation results show that the use of composite materials can produce negative permittivity and negative permeability, filter insertion loss is less than 1.0 db in the passband of 3.8 GHz to 10.6 GHz. And the group delay is about 0.20 ns near the center of the band, that is small enough to be applied to a wireless communication system.

Miniaturized High-Order Ultra-Wideband Bandpass Filters with Multiple Band Rejection Notches

This article, for the first time, presents a technique to realize controllable multiple band rejection notches in high-order miniaturized ultra-wideband filters employing the E-shaped microstrip structure. In this technique, the filter circuit is composed of a double layer substrate where on the bottom layer the main filter circuit uses a cascaded E-shaped microstrip; the structure is developed and on the top layer the notches circuit employs a square-loop shape, where the structure is etched. These two filter circuits are capacitively coupled using overlapping microstrip lines. To demonstrate the technique and design process, several examples are designed, fabricated, and measured. One particular example is a fifth-order ultra-wideband bandpass filter with multiple rejection notches in which each notched band has a second-order stopband response. The filter size is very small, about 5.7 mm × 6.5 mm × 0.63 mm, excluding the feeding ports.

A Hybrid Circuit for Spoof Surface Plasmons and Spatial Waveguide Modes to Reach Controllable Band-Pass Filters.

We propose a hybrid circuit for spoof surface plasmon polaritons (SPPs) and spatial waveguide modes to develop new microwave devices. The hybrid circuit includes a spoof SPP waveguide made of two anti-symmetric corrugated metallic strips and a traditional substrate integrated waveguide (SIW). From dispersion relations, we show that the electromagnetic waves only can propagate through the hybrid circuit when the operating frequency is less than the cut-off frequency of the SPP waveguide and greater than the cut-off frequency of SIW, generating efficient band-pass filters. We demonstrate that the pass band is controllable in a large range by designing the geometrical parameters of SPP waveguide and SIW. Full-wave simulations are provided to show the large adjustability of filters, including ultra wideband and narrowband filters. We fabricate a sample of the new hybrid device in the microwave frequencies, and measurement results have excellent agreements to numerical simulations, demonstrating excellent filtering characteristics such as low loss, high efficiency, and good square ratio. The proposed hybrid circuit gives important potential to accelerate the development of plasmonic integrated functional devices and circuits in both microwave and terahertz frequencies.

Novel Notched UWB Filter Using Stepped Impedance Stub Loaded Microstrip Resonator and Spurlines

This paper presents a novel ultrawideband (UWB) bandpass filter using stepped impedance stub loaded microstrip resonator (SISLMR). The proposed resonator is so formed to allow its four resonant frequencies in the UWB passband, which extends from 3.1 GHz to 10.6 GHz. Moreover, two spurline sections are employed to create a sharp notched-band filter for suppressing the signals of 5 GHz WLAN devices. Experimental results of the fabricated filters are in good agreement with the HFSS simulations and validate the design.

Design of UWB Bandpass Filter with Notched Band Using Distributed CRLH Transmission Lines

This study presents an Ultra-Wideband (UWB) filter with a notched band. The filter adopts novel Composite Right/Left-Handed (CRLH) Transmission Lines (TLs), the unit cell of which is theoretically analyzed to derive the design formulas. A model of the CRLH TLs is composed with distributed elements rather than lumped elements. Based on the results of the analysis, it is confirmed that the proposed structures are CRLH TLs. A UWB bandpass filter with a notched band is designed and fabricated using the induced formulas. The measurement results show that the fabricated UWB bandpass filter has an insertion loss of less than 3 dB, a bandwidth of 2.8-10.5 GHz and a rejection of greater than 27 dB at 5.75 GHz.

Multimode resonator based on composite right-/left-handed transmission line for UWB bandpass filter application

A new multimode resonator (MMR) using composite right-/left-handed transmission line (CRLH TL) is proposed and discussed. The CRLH TL structure is constructed by cascading interdigital coupled microstrip line sections on which short-ended stepped impedance stubs are loaded. Dispersion characteristic of the transmission line structure is obtained using the Bloch–Floquet theory. The resonator, which has multiresonances electrical behaviors, is especially suitable in ultrawideband (UWB) applications. An UWB filter is presented as an illustration. With transmission zeros introduced at upper stopband, the filter has a sharp skirt performance. In addition, rejection level at lower stopband also gets enhanced due to direct current suppression effects of the multimode resonator. The filter prototype is implemented and measured. The measured results validate the theoretical analysis and show that the filter has a sharp skirt and an out-of-band rejection level as good as 38 dB. Meanwhile, return loss is better than 16 dB. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:815–824, 2015.

Efficient UWB filter design technique for integrated passive device implementation

A new approach is proposed to act as an efficient design technique for the implementation of ultra-wideband (UWB) bandpass filters in integrated passive device technology. The proposed design is based on two major original contributions. First, the use of hourglass filter theory which, to the best of authors knowledge, has not been applied yet to such technology. Then, the minimisation of the number of inductors involved in the filter circuit through the zigzag technique. Implemented in 0.18 µm CMOS technology, the designed filter exhibits excellent performances such as two finite tunable transmission zeros, enhanced selectivity, a bandwidth covering the entire UWB spectrum of 3.1–10.6 GHz, a stopband rejection better than 15 dB throughout frequencies below 2.7 GHz and above 11 GHz, a good matching better than 11 dB, a minimum mid-band insertion loss of 1.8 dB and, finally, a sufficiently constant group delay. With these features and only 10 lumped elements, the proposed filter is one of the most promising compact filters for UWB applications.

Design of Compact UWB Bandpass Filter with Improved Out-of-band Performance Using Distributed CRLH Transmission Lines

This study presents an Ultra-Wideband (UWB) filter with improved out-of-band performance. The proposed filter adopts novel Composite Right/Left-Handed (CRLH) Transmission Lines (TLs), which are modeled with distributed elements instead of lumped elements. A unit cell of the CRLH TLs is theoretically analyzed to derive the design formulas. The analyzing results confirm that the proposed structures are CRLH TLs. A novel UWB bandpass filter with improved out-of-band performance is designed and fabricated using the induced formulas. The measurement results show that the fabricated UWB bandpass filter has an insertion loss of less than 2.8 dB, a bandwidth of 2.8-10.4 GHz and a rejection of more than 18 dB from 11.6 to 23.4 GHz.

Planar spoof plasmonic ultra-wideband filter based on low-loss and compact terahertz waveguide corrugated with dumbbell grooves.

Although subwavelength planar terahertz (THz) plasmonic devices can be implemented based on planar spoof surface plasmons (SPs), they still suffer from a little high propagation loss. Here the dispersion and propagation characteristics of the spoof plasmonic waveguide composed of double metal strips corrugated with dumbbell shaped grooves have been investigated. It has been found that much lower propagation loss and longer propagation length can be achieved based on the waveguide compared with the conventional spoof plasmonic waveguide with rectangular grooves. Moreover, the waveguide can implement a decrease in size of about 22%. An ultra-wideband THz plasmonic filter for planar circuits has been demonstrated based on the proposed waveguide. The experimental verification at the microwave frequency has been conducted by scaling up the geometry size of the filter.

A novel compact ultra-wideband (UWB) bandpass filter with triple-notched bands

A novel compact microstrip ultra-wideband (UWB) bandpass filter with three sharply notched bands and good selectivity is presented in this letter. Triple-notched bands filtering effects are achieved by adding open-circuited stubs and introducing asymmetric dual-line coupling structure to the feed lines, providing a high degree of adjusting freedom and not increasing the filter size. The frequencies of the notched bands and the upper stopband transmission zero can be independently controlled by adjusting the structural parameters of feed lines. Finally, a microstrip UWB filter with triple-notched bands is simulated and fabricated with good agreement.

Superconducting Ultra-Wideband (UWB) Bandpass Filter Design Based on Quintuple/Quadruple/ Triple-Mode Resonator

This paper analyzes the coupling modes when multiple hairpin resonators are coupled. Three kinds of current distribution and direction states exist in the coupled hairpin resonators: the current along the clockwise direction, the current along the counterclockwise direction, and no current density distribution. Different combinations of these current states lead to different coupling modes. In order to distinguish these modes, auxiliary lines are introduced between each two coupled resonators to denote each coupling mode, and this method is theoretically based on the analysis of the eigenvector of the coupling matrix. A simple and effective technique to construct multi-mode resonators (MMRs) is then proposed. An <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$n$</tex></formula> -mode resonator can be constructed by connecting <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$n$</tex> </formula> hairpins with small patches. Resonant modes of this class of MMRs were analyzed in detail using the proposed auxiliary lines method. Single stage and four stages of quintuple-mode resonators were used to design high-temperature superconducting ultra-wideband (UWB) filters by properly allocating the first five resonant peaks. Two UWB filters based on quadruple-mode and triple-mode resonators are also given. Parallel-coupled three lines were used to provide tight external couplings, which also generated two transmission poles. Measured results are in good agreement with the simulated ones without any tuning.

Compact ultra wide band filter using triangular patch resonators

A compact ultra wide band pass filter has been proposed in this paper. The band pass operation of the filter has been obtained with the combinations of high pass filter and low pass filter. The low pass filter used in the combined structure is designed using the triangular patch resonators and the high pass filter is designed using shorted stubs. The three different topologies to combine the low pass and high pass filter are compared. The final structure gives a very compact configuration of ultra wide band pass filter. The design methodology of the proposed filter is elaborated. The designed structure is simulated and fabricated. The group delay of the filter gives almost flat for the entire operation band. A good agreement has been seen between simulated and measured values of scattering parameters. The fractional band width has been achieved as 130%.

An Optimal Design of the Compact CRLH-TL UWB Filter Using a Modified Evolution Strategy Algorithm

This paper deals with an efficient optimization design method of a compact ultra wideband (UWB) filter which can improve the characteristics of the filter. The Evolution Strategy (ES) algorithm is adopted for the optimization and modified to suppress the ripple by inserting an additional step to the ES scheme. The algorithm has the ability to control the ripple of an insertion loss in a passband as a modified approach. During the modified ES, a structure of initial shape is changed a lot, while includes the stepped impedance (SI) and the composite right/left handed transmission line (CRLH-TL). And an optimized filter satisfies the UWB specifications on the stopband and passband with an acceptable insertion loss. The filter achieves a much developed shape, the size of 15 x 14mm, the 3dB bandwidth from 2.7 to 10.8GHz, the flat insertion-loss less than 1dB, the wide stopband with 12~20GHz, and an acceptable return loss.

Planar UWB Filter with Multiple Notched Band and Stopband with Improved Rejection Level

AbstractAnalysis and realization of a microstrip-based planar ultra-wideband (UWB) filter with integrated multiple notch elimination property and simultaneously extended upper stopband is proposed. Initially, a UWB filter based on back-to-back microstrip-to-CPW technology is designed. Later, multiple spiral defected ground structures (DGS) are embedded to obtain multiple passband notches. Further, double equilateral U (DEU)-type DGS are used to improve upon the rejection level in upper stopband. The multiple passband notches are results of embedded spiral-shaped DGS (SDGS), while extended upper stopband is the outcome of suppressed higher-order spurious harmonics. The flexible dual-attenuation poles of DEU-shaped DGS suppress the stopband harmonics and widen the stopband. An approximate lumped equivalent circuit model of the proposed filter is modelled. The filter is compact and its layout measures 25.26 mm × 11.01 mm. The measured result is in good agreement with the full-wave electromagnetic (EM) simulation and circuit simulation.

Compact planar UWB filter using cascaded resonators

This paper presents a planar ultra wide band filter employing chip inductors and complementary split ring resonators. Asymmetric interdigital coupled lines are used for achieving bandpass characteristics. Lower side transmission zeros are introduced using LC resonators consisting of chip inductors and circular patch capacitors. The filter has low insertion loss and flat group delay in its passband, steep roll off rate and good stopband attenuation. Measurement results for transmission and reflection characteristics of the fabricated filter are in good agreement with simulated response.

Switchable and Tunable Notch in Ultra-Wideband Filter Using Electromagnetic Bandgap Structure

A simple technique to reconfigure a notch filter employing a 1-D electromagnetic bandgap (EBG) structure, which is capacitively coupled to a microstrip line, is presented in this letter. The resonant nature of the EBG creates a notch in the transmission band. The notch filter is made reconfigurable/tunable by introducing an additional capacitive structure to change the size (geometry) of the EBG unit cell. The structure is connected or disconnected to the main structure (unit cell) by means of a PIN diode or varactor diode. Its application in notched-band ultra wideband (UWB) filter is demonstrated. A 450 MHz change in notch frequency is observed using PIN diode, and 340 MHz tuning range is observed using varactor diode.

A novel compact ultrawide band filter for reconfigurable notches

ABSTRACTA novel compact ultrawide band (UWB), bandpass filter (BPF) with reconfigurable and embedded notches at WiMAX (3.5 GHz) and WLAN (5.2 GHz) is proposed. UWB BPF is embedded with a rectangular resonator and improved stepped impedance resonator to introduce notched in the passband. Filter reconfiguration is achieved by varying the conductance of microstrip line. Filter response shows a sharp rejection of both WiMAX and WLAN bands. Experimental results are in good agreement with the simulated data. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:88–91, 2015