Dual Bandstop Research Articles

Tunable terahertz dual-band band-stop filter based on surface magnetoplasmons in graphene sheet array

Magnetically tunable terahertz dual-band band-stop filters are proposed based on the surface magnetoplasmons of graphene. The magnetoplasmons of a graphene rectangular sheet array can be attributed to the combination effects of the two edge plasmons along the length and width directions. Under external magnetic field the two plasmonic resonances are respectively blue-shifted and red-shifted, leading to different dips in the vertical transmission spectrum through the graphene array. Following this mechanism, narrow-band and wider-band band-stop filters with dual stop bands are theoretically obtained in composite structures consisting of graphene sheet array layers and semiconductor substrate layer. The influence brought by structural parameters and the chemical potential of graphene on the filtering performance are analyzed. Numerical results show the center frequencies of the two stop bands of the filters can be efficiently tuned by the intensity of the magnetic field.

Millimeter-Wave CMOS 30/80 GHz Sharp-Rejection Dual-Band Bandstop Filters Using TFMS Open-Stepped-Impedance Resonators

In this brief, for the first time, dual-band bandstop filters (DBBSF) for millimeter-wave operation at 30/80 GHz bands are presented in 0.18 μm CMOS process. The filter design is based on TFMS shunt open-ended stepped-impedance resonators, which exhibit dual stopband response with impedance controlled center frequencies and bandwidths. Lossless transmission line model is used for theoretical analysis, where the conditions for acquiring two stopbands and to achieve good stopband isolation are investigated using single and double resonators. Furthermore, an improved design for good passband at mid-band has been proposed, resulting in a DBBSF that could also replace a wideband bandpass filter with sharp-rejection on both sides. Two prototype filters with optimally compact geometries are fabricated and characterized to demonstrate dual-band bandstop characteristics at 30/80 GHz. The measured results are in good agreement with full-wave electromagnetic simulations.

Broadband Dual-Polarized Band-Absorptive Frequency-Selective Rasorber Using Absorptive Transmission/Reflection Surface

A dual-polarized broad band-absorptive frequency-selective rasorber (FSR) is proposed in this article. The FSR has a lowpass band with low insertion loss and a broad absorption band. It is a two-layer structure formed by a lossy surface cascaded an absorptive transmission/reflection surface (ATRS), in which the ATRS is constructed by one substrate with a resistive square loop on its top side and a double square loop on its bottom side. The working mechanisms of the proposed ATRS and FSR are completely studied by using their equivalent circuit models. The ATRS retains dual stopbands of the double square loop and suppresses the unwanted transmission pole of the double square loop. Then a broadband absorptive FSR is achieved. A sample of the proposed FSR is fabricated and measured. The measured results show that the proposed FSR has a lowpass band up to 860 MHz ( $\vert S_{21}\vert \ge -1$ dB) and a broad absorption band with bandwidth of 95.3% from 3.84 to 10.83 GHz ( $\vert S_{11}\vert \le -10$ dB and $\vert S_{21}\vert \le -10$ dB).

Infrared Frequency Selective Surface with Dual Stopband Based on Hexagonal Ring Structure

Infrared Frequency Selective Surface with Dual Stopband Based on Hexagonal Ring Structure

Dual band stop filter design via frequency transformation and synthesis with lumped resonators

This study presents a new compact design technique for dual band stop (DBS) filter. Analytical formulation of DBS frequency transformation/mapping is derived in terms of parametric representation of band characteristic of DBS filter. The analytical derivation of the transformation function is based on sequential application of classical low pass to band stop (LP to BS) and low pass to band pass (LP to BP) transformations. Assigned band characteristic of DBS filter can be achieved by applying the proposed transformation function on an LP prototype network. The explicit network topologies for DBS reactance mapping are presented. Several numerical examples are provided to validate the proposed mapping function. An implantation example of DBS filter for GSM900 and GSM1800/UMTS bands is given. Mixed element realisation of the designed filter and measurement results of the design are presented.

Design of Ultra-Wideband Tapered Slot Patch Antenna with Reconfigurable Dual Band-Notches

This paper presents an ultra-wideband tapered slot patch antenna with bi-directional radiation, reconfigurable for dual band-notched capability and fed by coplanar waveguide. The proposed antenna showed excellent ultra-wideband characteristics with bandwidth of (1.9–12 GHz). In order to reduce the interference of the narrow band communications represented by Worldwide Interoperability for Microwave Access radiation in the range (3.4–3.9) GHz and standard IEEE 802.11a. application (from 5.1 GHz to 6.1 GHz), the antenna was accompanied with adjustable dual-stop band capability in these bands. The dual-band notches are achieved with aid of inserting a parasitic single split ring resonator and etching a single circular complementary circle split ring resonator. The proposed antenna used epoxy (FR4) substrate material with ????r= 4.4 and dimensions of .

Interplay of dual photonic stopband in fluorescence enhancement from dye-doped photonic crystal heterostructures

Photonic crystal (PhC) structures with appropriate characteristics are necessary to control spontaneous emission from fluorophores while designing miniaturized lasers. We report the fabrication and detailed studies on the emission features of two different spectrally engineered PhC heterostructures made from dye-doped opal and one-dimensional (1-D) multilayer stack. Our results demonstrate notable enhancements of emission from PhC heterostructure enabled by the stopband overlap of three-dimensional (3-D) opals and 1-D multilayers. In the presence of the 1-D multilayer, the distributed feedback from opals further enhances the emission from the dye. We emphasize the role of the interplay of the spectral overlap of stopbands and the band edges in the dye-doped PhC heterostructures to control their emission features. The emission results obtained from our heterostructures are very much dependent on the relative spectral position of the stopbands of the constituent 1-D and 3-D photonic crystals. Input pump energy-dependent emission results indicate that such heterostructures are potential candidates for designing colloidal PhC-based lasers.

Highly isolated dual band stop two-element UWB MIMO antenna topology for wireless communication applications

A novel compact Ultra Wide Band (UWB) Multiple Input Multiple Output (MIMO) antenna with dual filtering property is proposed. Two monopole antennas with W-shaped and n-shaped slots on their radiating patch are arranged vertically to form the MIMO antenna topology. Each monopole is composed of a slotted radiating patch and a simple ground plane which yield band stop feature in Worldwide Interoperability for Microwave Access (WiMAX) and Wireless Local-Area Network (WLAN) frequency band. In the sequel, to enhance the isolation, a parasitic structure has been wiely embedded between two monopole antennas. Applying the aforementioned decoupling structure improves the isolation level from -17dB to -22dB. The proposed two-element MIMO antenna with vertical arrangement, covers UWB frequency range from 3.1 to 10.6 GHz with notches at WiMAX (3.3–3.8 GHz) and WLAN (5–6 GHz) bands. The inter element isolation is less than -22 dB and in most cases even is less than -25 dB over the entire operating frequency band. The obtained simulated and measured results confirms suitable good matching acceptable Envelope Correlation Coefficient (ECC), efficiency, group delay, and radiation patterns. All these gurantrees a promising performance for the proposed MIMO antenna.

Microstrip multi-stopband filter based on tree fractal slotted resonator

This paper presents the design and development of a new microstrip multi-stopband filter based on tree fractal slotted resonator. A single square patch with tree fractal slots of different iterations are employed for realizing dual stopband and tri-stopband filters. The tree fractal slotted resonators are generated from conventional square patch using an iterative tree fractal generator method. First, second and third level iterations of the tree fractal slot resonator are used to design dual and tri-stopband filters respectively. The first level iteration introduced for the tree fractal slot realizes dual bands at 2.64 GHz and 3.61 GHz while the second level iteration provides better stopband rejection and insertion loss at 2.57 GHz and 3.56 GHz. The tri-stopband filter generates three resonance frequencies at 1.53 GHz, 2.53 GHz and 3.54 GHz at third level iteration. By varying the slot length and width of the tree fractal slot, the resonant frequencies can be adjusted and stopbands of the proposed filter can be tuned for the desired unwanted frequency to be rejected. The proposed narrowband filters finds application in removing the interference of GPS and Wi-Max narrowband signals from the allotted bands of other wireless communication systems

Modeling of Grating Assisted Hybrid Plasmonic Filter and Its On-Chip Gas Sensing Application

A dual-band stop vertical hybrid plasmonic filter based on the silicon nitride fin Bragg grating (FBG) is designed and simulated in the infra-red band. It consists of the two silicon nitride FBGs embedded in the silicon waveguide separated by $L_{\mathrm{ SP}}$ spacing. Finite element method-based 3D-COMSOL simulation shows two stop band wavelengths at 1.462 and 1.515 $\mu \text{m}$ , respectively. Furthermore, its on-chip methane gas sensing application for coal mines is also investigated. The proposed filter-cum-sensor is the complementary metal–oxide–semiconductor compatible demonstrating 856.50-nm/RIU sensitivity, 120-RIU−1 figure of merit, $6.34\times 10^{-2}$ RIU limit of detection, and 0.52-nm/K temperature sensitivity.

Effect of rotational split ring resonator on dual bandstop filter

This paper presents analysis and design of a compact dual bandstop filter using an array of square split ring resonators (SSRR). The SSRR are placed in the ground to cut off the unwanted signals. The results show that the angular orientation of the inner ring offers the possibility of designing dual bandstop filter with a small size and simple structure.

Dual stop band frequency selective surface for C and WLAN band applications

A miniaturized unit cell design of Frequency Selective Surface (FSS) to produce stop band characteristics for two bands is presented. The presented unit cell structure is showing the band filtering characteristics for dual frequency band specifically C-band for satellite communication and Wireless Local Area Network (WLAN). The designed FSS structure is comprised of I shaped and modified I shaped metallic strips. The distinct unit cells of suggested are investigated for band filtering characteristics and finally integrated on a single unit cell for dual-band filtering applications. The I shaped and modified I shaped unit cell is producing band filtering properties at center frequencies like 4 GHz and 5.5 GHz respectively. The presented FSS design is modeled on an FR-4 substrate with dielectric constant of 4.4 and the dimension of the unit cell is 10 × 10 × 1.6 mm3. The fabricated FSS structure is simulated and measured for its characteristics verification like S11 and S21 and it has been found a satisfactory agreement in simulated and measured results.

An Infrared Frequency Selective Surface with Dual Stopband

In order to get the low transmission rate in both mid infrared atmospheric window and far infrared atmospheric window, an infrared frequency selective surface composed of two layers based on hexagonal ring structure was designed. Simulation analysis using CST electromagnetic software shown that the frequency selective surface had two stopbands in both 3μm~5μm and 8μm~15μm regions, of which the average transmittance is lower than 2.5%. Therefore, this frequency selective surface realized two stopbands in infrared wavebands; This paper analyzed the filtering mechanism of the frequency selective surface based on the effective medium theory. In the end, this paper researched the effect of electromagnetic wave polarization mode, incident angle and dielectric layer thickness on the transmission properties of the frequency selective surface. The results revealed that the transmission of frequency selective surface is insensitive to polarization mode and incident angle, while the dielectric layer thickness is an important factor to the transmittance of frequency selective surface.

Frequency Selective Surface for Infrared Transmission Suppression at Atmospheric Window

A double screen infrared frequency selective surface (FSS) with dual transmission stopbands was proposed and numerically investigated. Simulation results show that the infrared transmittance of the structure is lower than 10% in mid-infrared band (3~5 μm) and far-infrared band (8 ~14 μm).This structure is polarization insensitive to the incident electromagnetic waves. For a wide range of incident angles from 0° to 60°, the infrared transmittance of the structure is still lower than 25% in the band of interest. Compared with black body, the radiation ratio of structure is lower in the MWIR and LWIR ranges. The structure provide the potential applications for infrared stealth.

双阻带红外频率选择表面的设计

双阻带红外频率选择表面的设计

An Angularly Stable Dual-Band FSS With Closely Spaced Resonances Using Miniaturized Unit Cell

A novel miniaturized-element dual-band frequency selective surface (FSS) with closely spaced resonance is presented in this letter. The proposed FSS comprises of meander lines printed on a single-layer dielectric substrate to provide dual stopband characteristic. Compared to previously published spatial filters, the proposed FSS has better miniaturization characteristic having the unit-cell size of $0.065\lambda _{0} \times 0.065\lambda _{0}$ , where $\lambda _{0}$ corresponds to free space wavelength of the lower resonance frequency. In addition, the operating bands are closely located exhibiting the frequency ratio as low as 1.29. The surface current distribution and the equivalent circuit model are illustrated to explain the resonance behavior of the designed FSS. Furthermore, the proposed structure is polarization-independent and angularly stable for both TE and TM polarizations. A prototype of the dual-band FSS is fabricated and measured, which validates the simulated responses under normal and oblique incidence.

A compact dual stopband bandstop filter using defected SIR and Hilbert shape fractal structure

In this paper, a novel technique is proposed to design a dual band bandstop filter which is implemented with two defected stepped impedance resonators (SIRs) embedded on the input output transmission line. The embedded SIRs create a transmission zero at 2.5 GHz that generates the first stopband of the proposed filter. Introducing two Hilbert shaped fractal structure on the ground plane, the second stop band is employed at 3.5 GHz. The overall layout of the filter is realized with a size of 20 × 5 mm2. The proposed prototype is EM simulated and measured. The measured −10 dB bandwidth for first stopband is 0.1 GHz and for second stopband it is 0.14 GHz. The measured S-parameters exhibit an excellent out off band response with insertion loss less than 1.5 dB. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1345–1347, 2016

Dual stopband frequency selective surface by using half rings and slots

ABSTRACTIn this letter, a novel technique is proposed to design a dual stopband frequency selective surface (FSS) by combining a bandpass filter with its complementary structure in series. It displays flexibility to control the stopband frequencies which is the most attractive feature of this design. The proposed FSS filter is also very easy to fabricate, consisting of a single metal layer on a dielectric layer. A theoretical equivalent circuit model is proposed to characterize the structure. Explanation of the proposed filter response based on analysis of the equivalent circuit is discussed in detail. It is shown that the frequency response of the proposed FSS is almost the same for different incident angles. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1136–1139, 2016

Frequency and time domain analysis of a novel UWB antenna with dual band-notched characteristics

This paper presents the dual band notch characteristics of Ultra wideband (UWB) monopole antenna. Proposed antenna (30 × 30 mm2) consists of arrow shaped patch and truncated ground plane. Operating range of the proposed antenna (voltage standing wave ratio < 2) is 2.2–11 GHz. In order to achieve dual band stop characteristics, λ/2 open ended angularly separated slit pair has been inserted on the radiator for world interoperability for microwave access (WIMAX) (3.3–3.9 GHz) band rejection performance and wireless local area network (WLAN) (5.1–5.9 GHz) band rejection has been realized by introducing a pair of angularly separated λ/2 conductor backed plane (CBP). Using proper adjustment of angular separation for both slit pair and CBP pair, enhanced band rejection can be achieved for the WIMAX and WLAN band, respectively. The performance of antenna has been investigated in terms of frequency domain and time domain to assess its suitability in UWB communication.

Design of a CPW-fed UWB printed antenna with dual notch band using mushroom structure

A coplanar waveguide-fed planar hexagonal monopole ultra-wideband antenna with dual-band rejection characteristics is proposed in this paper. The desired notch frequencies at 3.5 and 5.5 GHz are realized by incorporating mushroom structures. The input impedance and surface current distributions are used for analysis and explanation of the effects of mushroom cells. The prototype and proposed antennas are fabricated and tested. From the measured results, the proposed antenna provides an operating band of 2.81–14.32 GHz for 2 ≤ voltage standing wave ratio (VSWR), while the dual-band stop function is in the frequency bands of 3.3–3.7 GHz and 5.10–5.88 GHz. Moreover, the antenna model also exhibits constant group delay and linear phase in the pass band. The proposed antenna has appreciable gain and efficiency over the whole operating band except the notch bands.