Showing papers on "Stopband published in 2017"

Resonance Characteristics of Substrate-Integrated Rectangular Cavity and Their Applications to Dual-Band and Wide-Stopband Bandpass Filters Design

Abstract: Resonance characteristics of substrate-integrated rectangular cavity (SIRC) are systematically analyzed in this paper. Synthesis design techniques of substrate-integrated waveguide (SIW) dual-band bandpass filters (BPFs) and wide-stopband BPFs are demonstrated on the basis of these characteristics. The design concept of dual-band BPFs is to add some extra single-mode SIRC resonators to dual-mode resonator filters to increase the degrees of freedom in extracting direct-coupling coefficients, while the external quality factors $Q_{e}$ and cross-coupling coefficients desired in two passbands can be realized simultaneously by determining proper offset position of the I/O ports and cross-coupling window, respectively. Consequently, all the design parameters including $Q_{e}$ and coupling coefficients $M_{ij}$ required for both the passbands could be satisfied. The principle of wide-stopband BPFs is to select the constitutive SIRC resonators with identical fundamental frequency but staggered higher order ones to suppress multispurious peaks to low levels and narrow bandwidths. Then emphasis is placed on the rejection of TE202 mode, with its resonant frequency two times of TE101 for all SIRC resonators, by centered I/O ports and coupling windows. Several experimental prototypes of SIW dual-band BPFs and wide-stopband BPFs are designed and fabricated to validate these concepts. The measured results are in excellent agreement with the simulations.

High-Gain and High-Aperture-Efficiency Cavity Resonator Antenna Using Metamaterial Superstrate

Abstract: In this letter, a high-gain, aperture-efficient cavity resonator antenna using metamaterial superstrate is reported. Highly reflective compact metamaterial surface resonating at 10.15 GHz with measured 3-dB bandwidth stopband characteristic of 4.10 GHz from 8.1 to 12.2 GHz is proposed. Material property of the metasurface is studied by using the free-space technique. Next, the metasurface is used as a superstrate to a patch antenna operating at 10.09 GHz, forming Fabry-Perot cavity. Gain enhancement of 11.85 dB in H-plane and 12.5 dB in E-plane with improved cross-polarization level and front-to-back ratio is observed. The prototype cavity antenna shows calculated gain of 16.35 dB achieving 92.42% of maximum gain due to effective aperture area in H-plane.

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

Abstract: 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.

Mode Coupling and Nonlinear Resonances of MEMS Arch Resonators for Bandpass Filters.

Abstract: We experimentally demonstrate an exploitation of the nonlinear softening, hardening, and veering phenomena (near crossing), where the frequencies of two vibration modes get close to each other, to realize a bandpass filter of sharp roll off from the passband to the stopband. The concept is demonstrated based on an electrothermally tuned and electrostatically driven MEMS arch resonator operated in air. The in-plane resonator is fabricated from a silicon-on-insulator wafer with a deliberate curvature to form an arch shape. A DC current is applied through the resonator to induce heat and modulate its stiffness, and hence its resonance frequencies. We show that the first resonance frequency increases up to twice of the initial value while the third resonance frequency decreases until getting very close to the first resonance frequency. This leads to the phenomenon of veering, where both modes get coupled and exchange energy. We demonstrate that by driving both modes nonlinearly and electrostatically near the veering regime, such that the first and third modes exhibit softening and hardening behavior, respectively, sharp roll off from the passband to the stopband is achievable. We show a flat, wide, and tunable bandwidth and center frequency by controlling the electrothermal actuation voltage.

An On-Chip Bandpass Filter Using a Broadside-Coupled Meander Line Resonator With a Defected-Ground Structure

Abstract: An on-chip bandpass filter (BPF) is designed and fabricated in a 0.13- $\mu \text{m}$ SiGe (Bi)-CMOS technology. This BPF consists of a broadside-coupled meander-line resonator (BCMLR) in conjunction with a defected-ground structure (DGS). By simply grounding a BCMLR, the resonator can be converted into a BPF. Further applying a DGS to this BPF, an additional transmission zero can be generated in the high-frequency band. To understand the fundamentals of this design, an $LC$ -equivalent circuit is given for investigation of the transmission zeros and poles. The measured results show that the BPF has a center frequency at 33 GHz with a bandwidth of 18%. The minimum insertion loss is 2.6 dB, while the maximum stopband attenuation is 44 dB. The chip size, excluding the pads, is only 0.038 mm2 ( $0.126\times0.3$ mm $^{2}$ ).

Design of a Low Profile and Compact Omnidirectional Filtering Patch Antenna

Abstract: A low profile omnidirectional patch antenna with filtering response is investigated in this paper. The triangular patch antenna is axially fed by a probe at its center, exciting both its TM10 and TM11 modes. Comparing with the traditional circular patch, the triangular patch can not only minimize the patch size but also can generate a radiation null at the upper band edge. A ring slot and a series of shorting vias are introduced into the patch to merge the two modes, enhancing the bandwidth of the passband. The combination of the two elements simultaneously generates a radiation null at the lower band edge. Consequently, a compact filtering patch antenna with quasi-elliptic bandpass response is obtained without involving specific filtering circuits. The prototype with profile of $0.03~\lambda _{0}$ has a 10-dB impedance bandwidth of 8.9% (4.3–4.7 GHz), an average gain of 6.0 dBi within passband, an out-of-band suppression level of more than 30 dB within lower stopband (0–3.6 GHz), and more than 20 dB within upper stopband (5.1–6.3 GHz).

Conception of a 3D metamaterial-based foundation for static and seismic protection of fuel storage tanks

Abstract: Fluid-filled tanks in tank farms of industrial plants can experience severe damage and trigger cascading effects in neighboring tanks due to large vibrations induced by strong earthquakes. In order to reduce these tank vibrations, we have explored an innovative type of foundation based on metamaterial concepts. Metamaterials are generally regarded as manmade structures that exhibit unusual responses not readily observed in natural materials. If properly designed, they are able to stop or attenuate wave propagation. Recent studies have shown that if locally resonant structures are periodically placed in a matrix material, the resulting metamaterial forms a phononic lattice that creates a stop band able to forbid elastic wave propagation within a selected band gap frequency range. Conventional phononic lattice structures need huge unit cells for low-frequency vibration shielding, while locally-resonant metamaterials can rely on lattice constants much smaller than the longitudinal wavelengths of propagating waves. Along this line, we have investigated 3D structured foundations with effective attenuation zones conceived as vibration isolation systems for storage tanks. In particular, the three-component periodic foundation cell has been developed using two common construction materials, namely concrete and rubber. Relevant frequency band gaps, computed using the Floquet-Bloch theorem, have been found to be wide and in the low-frequency region. Based on the designed unit cell, a finite foundation has been conceived, checked under static loads and numerically tested on its wave attenuation properties. Then, by means of a parametric study we found a favorable correlation between the shear stiffness of foundation walls and wave attenuation. On this basis, to show the potential improvements of this foundation, we investigated an optimized design by means of analytical models and numerical analyses. In addition, we investigated the influence of cracks in the matrix material on the elastic wave propagation, and by comparing the dispersion curves of the cracked and uncracked materials we found that small cracks have a negligible influence on dispersive properties. Finally, harmonic analysis results displayed that the conceived smart foundations can effectively isolate storage tanks.

Design of Compact Wide Stopband Microstrip Low-pass Filter using T-shaped Resonator

Abstract: In this letter, a compact microstrip low-pass filter (LPF) using T-shaped resonator with wide stopband is presented. The proposed LPF has capability to remove the eighth harmonic and a low insertion loss of 0.12 dB. The bandstop structure using stepped impendence resonator and two open-circuit stubs are used to design a wide stopband with attenuation level better than −20 dB from 3.08 up to 22 GHz. The proposed filter with −3-dB cutoff frequency of 2.68 GHz has been designed, fabricated, and measured. The operating of the LPF is investigated based on equivalent circuit model. Simulation results are verified by measurement results and excellent agreement between them is observed.

Wideband Single-Ended and Differential Bandpass Filters Based on Terminated Coupled Line Structures

Abstract: In this paper, a novel terminated coupled line structure (TCLS) is introduced, which is constructed by a coupled line section and four terminations loaded on it. Introducing different kinds of terminations, three types of bandpass filters (BPFs) based on TCLSs are proposed, theoretically analyzed, and fabricated, including two single-ended wideband BPFs with fractional bandwidths (FBWs) of 67% and 40% respectively, and a wideband differential BPF with 74% differential-mode FBW. These BPFs can achieve wide passband bandwidth, low in-band insertion loss, high passband selectivity, as well as deep stopband rejection performance simultaneously, benefited from the multiple transmission zeros and transmission poles obtained by the TCLSs. The practical design procedures of these BPFs are presented and explained. The agreement among theoretical predictions, EM-simulated, and measured results validates our proposed filter structures. Finally, the generalized multistage filter topology based on TCLSs is proposed to design high-order filters with better filtering performances.

Compact On-Chip Bandpass Filter With Improved In-Band Flatness and Stopband Attenuation in 0.13- $\mu \text{m}$ (Bi)-CMOS Technology

Abstract: In this letter, an on-chip miniaturized bandpass filter (BPF) is presented, which is based on a grounded center-tapped ring resonator (CTRR) with shunt capacitive loading. To analyze the principle of this design, a simple but effective equivalent circuit model is provided. Using this model, it is easy to show that the CTRR-based approach has a potential to generate two transmission poles within the passband. Compared with the conventional single-pole-based approach, this dual-pole design not only possesses a flexibility of controlling the passband width, but also has better flatness of insertion loss in the passband. In addition, this approach is able to significantly improve the stopband performance. To further demonstrate the feasibility of this approach in practice, the structure is implemented and fabricated in a commercial 0.13- $\mu \text{m}$ (Bi)-CMOS SiGe technology. The measured results show that the BPF has a center frequency at 33 GHz with a bandwidth of 42.4%. The minimum insertion loss is 2.6 dB, while the stopband rejection is maintained to be better than 20 dB beyond 58 GHz. The chip, excluding the pads, is very compact at only 0.03 mm2 ( $0.11\times0.28$ mm $^{{2}}{)}$ .

Design for structural vibration suppression in laminate acoustic metamaterials

Abstract: This paper investigates the stopband of laminate acoustic metamaterials, which is composed of carbon-fiber-reinforced polymer (CFRP) and a periodic array of mass-spring-damper subsystems integrated with the laminates to act as vibration absorbers. Based on the mathematical model derived in this work, a wide stopband is observed by dispersion analysis. The frequency response analysis is performed to confirm its stopband behavior for a finite laminate acoustic metamaterial. Due to the superior strength to weight ratio of CFRP, the laminate acoustic metamaterials are able to have a much wider stopband than the conventional metamaterial plates proposed in recent years. In addition, the effects of the relevant parameters on the stopband of laminate acoustic metamaterial are discussed in this work. The excellent performance of laminate acoustic metamaterials has been applied to design the vehicle door, and the vibration of the vehicle door is suppressed significantly.

Compact Quad-Band Bandpass Filter Using Quad-Mode Stepped Impedance Resonator and Multiple Coupling Circuits

Abstract: A compact quad-band bandpass filter using quad-mode stepped impedance resonator (QMSIR) is investigated in this paper. To get suitable coupling within the four passbands, the multiple coupling circuits between the input/output ports and QMSIR are applied. Based on the symmetry of the QMSIR, even- and odd-mode theory is used to analyze the equivalent circuits of the QMSIR. Design equations are derived, and they are used to guide the design of the circuits. Four passbands can be easily tuned by its physical dimensions. Upper stopband is improved by adding the open-loop SIRs at both I/O ports. Transmission zeros among each passbands are generated, resulting in high isolation and frequency selectivity. An experimental circuit is fabricated and evaluated to validate the design concept. The measurement results are in good agreement with the full-wave simulation results.

Design for structural vibration suppression in laminate acoustic metamaterials

Abstract: This paper investigates the stopband of laminate acoustic metamaterials, which is composed of carbon-fiber-reinforced polymer (CFRP) and a periodic array of mass-spring-damper subsystems integrated with the laminates to act as vibration absorbers Based on the mathematical model derived in this work, a wide stopband is observed by dispersion analysis The frequency response analysis is performed to confirm its stopband behavior for a finite laminate acoustic metamaterial Due to the superior strength to weight ratio of CFRP, the laminate acoustic metamaterials are able to have a much wider stopband than the conventional metamaterial plates proposed in recent years In addition, the effects of the relevant parameters on the stopband of laminate acoustic metamaterial are discussed in this work The excellent performance of laminate acoustic metamaterials has been applied to design the vehicle door, and the vibration of the vehicle door is suppressed significantly Key words: laminate acoustic metamaterials; stop-band; local resonance; CFRP

Rainbow trapping of ultrasonic guided waves in chirped phononic crystal plates

Abstract: The rainbow trapping effect has been demonstrated in electromagnetic and acoustic waves. In this study, rainbow trapping of ultrasonic guided waves is achieved in chirped phononic crystal plates that spatially modulate the dispersion, group velocity, and stopband. The rainbow trapping is related to the progressively slowing group velocity, and the extremely low group velocity near the lower boundary of a stopband that gradually varies in chirped phononic crystal plates. As guided waves propagate along the phononic crystal plate, waves gradually slow down and finally stop forward propagating. The energy of guided waves is concentrated at the low velocity region near the stopband. Moreover, the guided wave energy of different frequencies is concentrated at different locations, which manifests as rainbow guided waves. We believe implementing the rainbow trapping will open new paradigms for guiding and focusing of guided waves. Moreover, the rainbow guided waves with energy concentration and spatial separation of frequencies may have potential applications in nondestructive evaluation, spatial wave filtering, energy harvesting, and acoustofluidics.

A Compact Bandpass Wilkinson Power Divider With Ultra-Wide Band Harmonic Suppression

Abstract: A Wilkinson power divider (WPD) with bandpass property and an ultra-wide band harmonic suppression is proposed in this letter. The frequency-selecting coupling structure is embedded to the conventional quarter-wavelength transmission line, which can realize an ultra-wide harmonic suppression with three transmission zeros. Short-ended meander line stubs are shunted at the both output ports for dc block and provide an extra transmission zero for the passband. The proposed WPD operates with a −20 dB bandwidth from 1.74 to 3.71 GHz with an ultra-wide stopband to suppress the dc, $3f_{0}$ , $5f_{0}$ , and $7f_{0}$ harmonic components. The proposed WPD has a compact size of 14.65 mm $\times19.64$ mm ( $0.19\lambda _{g} \times 0.25\lambda _{g})$ .

Compact Ultra-Wideband Bandpass Filter With Improved Upper Stopband Using Open/Shorted Stubs

Abstract: A compact ultra-wideband (UWB) bandpass filter with improved upper stopband using open/shorted stubs is proposed in this letter. Seven transmission zeros in the upper stopband can be realized by different open/shorted stubs. The bandwidth of the UWB bandpass filter can be adjusted easily by changing the characteristic impedance of the open/shorted stubs. A UWB bandpass filter with 3-dB fractional bandwidth of 123% (0.5-1.9 GHz) is fabricated and measured. Good agreement can be observed between simulated and measured performances.

Design of a Compact UWB Filter With High Selectivity and Superwide Stopband

Abstract: This letter presents a design of compact ultra-wideband bandpass filter (BPF) with high selectivity and superwide stopband. Three resonant modes from the multiple-mode resonator (MMR) based on half-mode substrate integrated waveguide (HMSIW) structure and four resonant modes from a pair of electromagnetic bandgap loaded parallel-coupled lines can constitute a wideband performance. Superwide stopband can be achieved and two transmission zeros are realized on both sides of the passband to improve the filter selectivity. A prototype of the BPF operating from 3.1 to 10.4 GHz with an extremely broad stopband region from 10.7 to 24 GHz and a rejection level of 15 dB is demonstrated in the measured results.

Stopband Frequency Selective Surface With Ultra-Large Angle of Incidence

Abstract: In this letter, a stopband frequency selective surface (FSS) with great incident angle independence and polarization stability is proposed and fabricated. Each element of the FSS consists of a cross spiral patch and four same second iteration of H-shaped fractal parts in C4 rotation symmetry. This FSS exhibits great stability with the incident angle ranging from 0° to 80° for both TE and TM polarizations. In addition, patch dimension of the FSS element can tune the resonant frequency. However it has a negligible influence on incident angle independence and polarization stability. This means the proposed FSS can be applied in different frequency ranges and has potential values in practical applications. Both simulation and measurement of this FSS demonstrate stable transmission characteristics under different incident angles and polarizations and show satisfactory consistence.

Multifunctional Reconfigurable Filter Using Transversal Signal-Interaction Concepts

Abstract: A novel multifunctional reconfigurable filter with three different transmission modes using transversal signal-interaction principles is proposed. These three operational modes allow to reconfigure the engineered filtering device as ultra-wideband bandpass filter, narrow-band bandpass filter (NB BPF), and ultra-wideband band-stop filter (UWB BSF). By turning on/off the RF switches, the transmission lines and stubs can be dynamically connected or disconnected so that the three transmission modes can be discretely selected. For the UWB-BPF mode, the 3-dB bandwidth is 95.7% (1.51–4.38 GHz) with minimum in-band insertion loss of 0.94 dB. For the NB-BPF mode, the 3-dB bandwidth is 25.3% (2.55–3.29 GHz), the minimum in-band insertion loss is 0.8 dB, and the stopband rejection is higher than 11.6 dB. For the UWB-BSF mode, the 3-dB bandwidth is 106% (1.41–4.59 GHz) with in-band insertion loss above 10 dB.

Novel Broadband Filtering Slotline Antennas Excited by Multimode Resonators

Abstract: A novel type of slotline antenna excited by multimode resonators are proposed in this letter. To widen the impedance bandwidth, two types of resonant modes are excited, including slotline mode and stub-loaded resonator mode. An equivalent multipoles filtering network is given for providing a physical insight into the in-band property. Two prototype antennas are finally designed and fabricated to experimentally validate the principle and design approach. Experimental results exhibit that proposed antennas feature not only broad impedance bandwidth but also good filtering response such as flat gain frequency response, sharp bandedge characteristic, as well as high stopband suppression.

Design of High-Performance Filtering Balun Based on TE01δ-Mode Dielectric Resonator

Abstract: This paper presents a fusion design approach of high-performance filtering balun based on the ring-shaped dielectric resonator (DR) for the first time. According to the electromagnetic (EM) field properties of the TE01δ mode of the DR cavity, it can be differentially driven or extracted by reasonably placing the orientations of the feeding probes, which answers for the realization of unbalanced-to-balanced conversion. As a result, the coupling between the resonators can refer to the traditional single-ended design, regardless of the feeding scheme. Based on this, a second-order DR filtering balun is designed by converting a four-port balanced filter to a three-port device. Within the passband, the excellent performance of amplitude balance and $\text{180}^{\circ}$ phase difference at the balun outputs can be achieved. To improve the stopband rejection by suppressing the spurious responses of the DR cavity, a third-order filtering balun using the hybrid DR and coaxial resonator is designed. It is not rigorously symmetrical, which is different from the traditional designs. The simulated and measured results with good accordance showcase good filter and balun functions at the same time.

Novel Tunable Bandstop Resonators in SIW Technology and Their Application to a Dual-Bandstop Filter with One Tunable Stopband

Abstract: Two novel tunable bandstop resonators in substrate integrated waveguide (SIW) technology are presented: a ridged SIW resonator and an open-ended coplanar waveguide (CPW) resonator that is etched into the SIW’s top metallization. The ridged SIW resonator shows a tuning range of 200 MHz at 5.54 GHz. The CPW resonator has a tuning range of 600 MHz at 3.8 GHz. The two bandstop resonators are combined to design a dual-band bandstop filter with one tunable stopband. Measured results confirm that the tunable bandstop circuits presented in this letter can be effectively used in reconfigurable SIW systems.

Cognitive Phase-Only Sequence Design With Desired Correlation and Stopband Properties

Abstract: This paper considers the phase-only sequence design problem for a cognitive radar in order to achieve both the desired autocorrelation and the stopband properties, which is useful to obtain good range compression as well as the spectral compatibility. We develop a new objective function accounting for the weighted integrated sidelobe level and the spectral power within specific stopbands. An iteration algorithm based on pattern search (PS) is proposed to minimize the nonconvex multidimensional objective function with the continuous phase case, which is split into multiple one-dimensional problems that are simplified and solved with closed-form solutions. In particular, the PS algorithm can be applied to the discrete phase case. Finally, we evaluate the effectiveness of the PS algorithm compared with the weighted-stopband cyclic algorithm new algorithm via numerical simulations in terms of the autocorrelation function, the spectral power function, and the convergence speed.

Quarter-mode circular cavity substrate integrated waveguide filtering power divider with via-holes perturbation

Abstract: A compact filtering power divider composed of two quarter-mode circular cavities based on the substrate integrated waveguide is proposed. Two extra perturbing via-holes added in each side of the quarter-mode circular cavity achieve a selective bandpass filtering response and improve the performance of the upper stopband. The proposed FPD operates at 9.1 GHz with a 3 dB fractional bandwidth of 19.8%. The insertion loss in operating band is <; 1.6 dB and the input return loss is better than 16 dB. The amplitude and phase imbalances between the two outputs are measured better than 0.6 dB and 3.5°, respectively. The measured results exhibit good agreement with the simulated ones.

Solid-State Terahertz Superresolution Imaging Device in 130-nm SiGe BiCMOS Technology

Abstract: Breaking through diffraction limit at terahertz frequencies is currently performed with the near-field scanning optical microscopy, which suffers from low integration and sensitivity limitations. In this paper, a solid-state superresolution imaging device in 130-nm SiGe BiCMOS technology operating around 534–562 GHz is presented. The device exhibits a single-chip integration of the complete imaging functionality, including a tunable CW illumination source, near-field sensing, and power detection with a high response of up to 9.65 $\mu \text{A}$ and a noise-equivalent power of around 15–21 pW $/\sqrt {\text {Hz}}$ at 60 kHz. Here, the stopband characteristics of a novel cross-bridged double split-ring resonator are exploited as an object-tunable transmission gate between a 3-push Colpitts oscillator and a simple HBT power detector. The resonator features a 3-D topography to achieve high-spatial confinement of the surface near-fields and is capable of resolving structural details with an estimated lateral resolution down to 10–12 $\mu \text{m}$ . For a separate antenna-coupled oscillator breakout, a radiated power of up to 28.2 $\mu \text{W}$ was measured. Furthermore, a 2-D raster-scanned superresolution image with a remarkable signal-to-noise ratio of 42 dB was captured for the device operating even at dc.