Spurious Response Research Articles

Investigation of New Microstrip Bandpass Filter Based on Patch Resonator with Geometrical Fractal Slot.

A compact dual-mode microstrip bandpass filter using geometrical slot is presented in this paper. The adopted geometrical slot is based on first iteration of Cantor square fractal curve. This filter has the benefits of possessing narrower and sharper frequency responses as compared to microstrip filters that use single mode resonators and traditional dual-mode square patch resonators. The filter has been modeled and demonstrated by Microwave Office EM simulator designed at a resonant frequency of 2 GHz using a substrate of εr = 10.8 and thickness of h = 1.27 mm. The output simulated results of the proposed filter exhibit 22 dB return loss, 0.1678 dB insertion loss and 12 MHz bandwidth in the passband region. In addition to the narrow band gained, miniaturization properties as well as weakened spurious frequency responses and blocked second harmonic frequency in out of band regions have been acquired. Filter parameters including insertion loss, return loss, bandwidth, coupling coefficient and external quality factor have been compared with different values of perturbation dimension (d). Also, a full comparative study of this filter as compared with traditional square patch filter has been considered.

An algorithm for recognizing linear objects in aerial photos automatically

A new algorithm for detecting linear infrastructural objects in aerial photos is presented. It is assumed that these objects pass through the whole image: beginning at one side and finishing at the opposite one. It is also assumed that the altitude of shooting and the image scale are invariable. The presented algorithm synthesizes the operation of an edge detector, a ridge detector, and the Hough accumulator into an object-of-interest mask excluding lots of spurious responses, and it completes missing information missed by detectors. First of all the image is preprocessed and anisotropically and repeatedly shrunk along the direction of the linear object and synthesis is performed by finding the shortest paths in a graph. The graph is presented in the form of a mesh, where each mesh node corresponds to a pixel of the shrunk image. At each node on the edges and in ridge lines, its energy is calculated, which is the reliability of this pixel. Then, the path that maximizes the sum of energies at the nodes is determined by considering its curvature. The obtained paths form a mask of linear objects. The algorithm is verified by using aerial photos for different seasons, and it demonstrates proper results (accuracy is ~80%).

Enhanced VOT on Foggy Videos Using Probabilistic Estimation Scheme

Objectives: Visual object tracking allude the process for tracking the path of the object in the video sequence. Tracking of the object under the foggy environment is the challenging task in the video sequence. There is a great need to implement spectral analysis for the visual attention tracking model. The proposed methodology deals with object tracking using Dubbed Density of Fog Assessment based Defogger (DEFADE) filter to resist environment based detail restoration. Methods/Statistical analysis: DEFADE guided filter is used to improve the visual detail of the frame. Then frames are moved to learning network where particle region is detected and then is registered using Binary Pixel Distance Mapping (BPDM). Further Calculation of color values for the given object or selected object in the entire three channels RGB (Red, Green, Blue). The spectral analysis of visual attention tracking model is compared with the proposed approach using BPDM_CMF model. In this system an existing filter for binary conversion and color filtering was used to evaluate and estimate the trajectory of the tracked objects in foggy weather affected videos. In case of visual tracking and object detection, multi-scale detection methods constitute to combine the effort of object detection in spatial scale using BPDM with Color Mean Filter (CMF) and a defogging based spurious response inherent method for multiscale removal of fog in tracking videos and improve the fine edge tracking with reduce error probability detection between frames in a temporal tracking method. Findings: The execution of the proposed framework has been contrasted and the before technique. The proposed method works more efficiently under the foggy environment for tracking the objects in the video sequence. Application/Improvements: Automatic Recognition of the object in the video sequence. Defogging has been efficiently used in identifying the humans on the basis of trajectory

Spurious-free Lamb wave resonators with protrusion structures

In this letter, we demonstrate a technique to eliminate the spurious modes in aluminum nitride Lamb wave resonators (LWRs). The transverse acoustic wave characteristics are examined, and a resonance modulation theory on the regulation of mechanical boundary conditions is deducted. As examples of embodiments, vertical and lateral protrusion structures are proposed for the suppression. Finite element analysis verifies that the employment of these structures effectively restrains the transverse modes, and the measured electrical performance of the LWR with protrusions demonstrates an 11 dB reduction in the spurious response.

Estimation and Inference in Over-Identified Structural Factor-Augmented VAR Models

During the past decade, high-dimensional factor models have been widely used for structural analysis in the literature, where the effects of structural shocks are often estimated under just-identifying restrictions. However, as the number of restrictions in a factor model setup can be large due to its high dimensionality, the structural shocks are over-identified. This paper develops a new estimator for the impulse response functions with a fixed number of over-identifying restrictions. The proposed identification scheme nests the conventional just-identified recursive scheme as a special case. We establish the asymptotic distributions of the new estimator and develop test statistics for the over-identifying restrictions. Simulation results show that adding a few more over-identifying restrictions can lead to a substantial improvement in estimation accuracy for impulse response functions at both zero and nonzero horizons. We estimate the effects of the monetary policy shock based on a U.S. macroeconomic data set. The result shows that our over-identified scheme can help to improve estimation efficiency and eliminate incorrect restrictions that lead to spurious impulse responses.

COMPACT MICROSTRIP BAND-PASS FILTER FOR EMI REDUCTION

Compact microstrip band-pass filter design using parallel coupled lines is presented in this paper. The microstrip lines are calculated and constructed using CST studio with two input and output ports of the filter structure are printed over Defected Ground Structure (DGS).The proposed symmetrical structure offers a simple and compact design while exhibiting an improved stop-band characteristics in comparison to conventional coupled microstrip line filter structure. The simulation and measurements of 2GHz prototype band pass filter are presented. The measured result agrees well with the simulation data. Compared with conventional parallel coupled line band pass filter, the second, third and fourth spurious responses are suppressed; in addition, the size of the prototype filter circuit is reduced up to 20.8%.

Dissociation of perception and action in audiovisual multisensory integration.

The ‘temporal rule’ of multisensory integration (MI) proposes that unisensory stimuli, and the neuronal responses they evoke, must fall within a window of integration. Ecological validity demands that MI should occur only for physically simultaneous events (which may give rise to non‐simultaneous neural activations), and spurious neural response simultaneities unrelated to environmental multisensory occurrences must somehow be rejected. Two experiments investigated the requirements of simultaneity for facilitative MI. Experiment 1 employed an reaction time (RT)/race model paradigm to measure audiovisual (AV) MI as a function of AV stimulus‐onset asynchrony (SOA) under fully dark adapted conditions for visual stimuli that were either rod‐ or cone‐isolating. Auditory stimulus intensity was constant. Despite a 155‐ms delay in mean RT to the scotopic vs. photopic stimulus, facilitative AV MI in both conditions occurred exclusively at an AV SOA of 0 ms. Thus, facilitative MI demands both physical and physiological simultaneity. Experiment 2 investigated the accuracy of simultaneity and temporal order judgements under the same stimulus conditions. Judgements of AV stimulus simultaneity or temporal order were significantly influenced by stimulus intensity, indicating different simultaneity requirements for these tasks. The possibility was considered that there are mechanisms by which the nervous system may take account of variations in response latency arising from changes in stimulus intensity in order to selectively integrate only those physiological simultaneities that arise from physical simultaneities. It was proposed that separate subsystems for AV MI exist that pertain to action and perception.

Suppression of Harmonics in Microstrip Filters Using a Combination of Techniques

Existing and newly adapted techniques for suppressing harmonic responses in microstrip filters were combined. Stagger tuning using additional stubs to shift the resonances has been adapted to quarter-wave resonators and extended to the seventh-order spurious response. Suitable resonator overlap provided transmission zeroes to cancel spurious peaks. Coupling capacitor pads acting as shorting stubs have been developed. Spurious responses were suppressed to better than $-{\hbox{33 dB}}$ , up to 6.3 GHz, in a measured filter with 1-GHz center frequency and 42% bandwidth. Suitably placed resistors have depressed the spurious level further to $-{\hbox{50 dB}}$ up to 5.6 GHz, with only 0.07-dB extra passband loss.

High-Temperature Superconducting Bandpass Filter Using Asymmetric Stepped-Impedance Resonators With Wide-Stopband Performance

This paper presents a wide-stopband high-temperature superconducting (HTS) bandpass filter (BPF). The filter is implemented by the asymmetric stepped-impedance resonators (SIRs) with only one step discontinuity, which leads to low loss and compact size. With varied characteristic impedance ratios and length ratios, the diversity of asymmetric SIR has been studied, and the spurious resonant-mode responses are discussed. Adopting different asymmetric SIR units operated at the same fundamental frequency $f_{0}$ (2.4 GHz), its wide upper stopband can be realized by dispersing the higher order spurious resonant modes of these resonators. Furthermore, a modified input/output (I/O) feedline structure has been utilized to enhance the stopband performance. Finally, a fourth-order HTS BPF for wireless application is designed and fabricated on a MgO wafer with double-sided YBCO films. The filter measurement shows excellent performance with 0.05-dB minimum insertion loss and better than −20-dB rejection level in the stopband up to 10.46 GHz (about 4.4 $f_{0}$ ). In addition, the size of the HTS filter is 12.45 mm $\times$ 23 mm (i.e., 0.256 $\lambda_g$ by 0.472 $\lambda_g$ , where $\lambda_g$ is the guided wavelength at the center frequency).

Dissociation of Perception and Action in Audiovisual Multisensory Integration

The 'temporal rule' of multisensory integration (MI) proposes that unisensory stimuli, and the neuronal responses they evoke, must fall within a window of integration. Ecological validity demands that MI should occur only for physically simultaneous events (which may give rise to non-simultaneous neural activations), and spurious neural response simultaneities unrelated to environmental multisensory occurrences must somehow be rejected. Two experiments investigated the requirements of simultaneity for facilitative MI. Experiment 1 employed an reaction time (RT)/race model paradigm to measure audiovisual (AV) MI as a function of AV stimulus-onset asynchrony (SOA) under fully dark adapted conditions for visual stimuli that were either rod- or cone-isolating. Auditory stimulus intensity was constant. Despite a 155-ms delay in mean RT to the scotopic vs. photopic stimulus, facilitative AV MI in both conditions occurred exclusively at an AV SOA of 0 ms. Thus, facilitative MI demands both physical and physiological simultaneity. Experiment 2 investigated the accuracy of simultaneity and temporal order judgements under the same stimulus conditions. Judgements of AV stimulus simultaneity or temporal order were significantly influenced by stimulus intensity, indicating different simultaneity requirements for these tasks. The possibility was considered that there are mechanisms by which the nervous system may take account of variations in response latency arising from changes in stimulus intensity in order to selectively integrate only those physiological simultaneities that arise from physical simultaneities. It was proposed that separate subsystems for AV MI exist that pertain to action and perception.

Design of Small-size and Low-loss LTCC Filters on Capacitively Loaded Cavities

Design of microwave filters for portable electronics is complicated by conflicting requirements to be met simultaneously such as high selectivity, low insertion loss and compact size. Substrate integrated waveguide (SIW) technology allows designing low-profile high-Q resonators and low-loss bandpass filters based thereof. However, SIW filters are not well-suited for telecommunication applications because of remarkably large size in plane. The size of a SIW cavity can be dramatically reduced by a capacitive loading. Capacitively loaded cavities (CLCs) operating in the TM110 mode can be as small as 1/8 of the guided wavelength and even smaller, i.e. comparable in size with lumped-element resonators. Although the unloaded Q-factor decreases proportionally to cavity size, miniaturized CLCs can exhibit much higher Q-factor than that of lumped-element resonators. This paves the way for designing small-size and low-loss filters for wireless communications and different applications. Miniaturized capacitively loaded SIW cavities are favorably implemented by means of the low temperature co-fired ceramics (LTCC) technology. The goal of the paper is to demonstrate manifold possibilities and flexibility offered by the LTCC technology to the design of advanced microwave filters on CLCs. Different design and manufacturing aspects are considered. Various design examples of high-performance LTCC resonators and filters for single- and dual-band wireless applications are presented. The designed resonators and filters were manufactured using the commercial DuPont Green Tape 951 LTCC system. The LTCC filters on miniaturized CLCs are shown advantageous with regard to small size, low loss, and absence of spurious response over a wide frequency range.

Transverse Mode Spurious Resonance Suppression in Lamb Wave MEMS Resonators: Theory, Modeling, and Experiment

This paper presents a transverse mode suppression theory and its experimental verification through aluminum nitride Lamb wave resonators (LWRs) operating at 142 MHz. An effective 2-D approximation model of the LWR is proposed, based on which the origin of transverse modes in LWR is investigated. The displacement distribution, resonant frequencies, and electromechanical coupling coefficients $( k_{t}^{2})$ of the main mode and its auxiliary transverse modes are obtained. A spurious mode suppression theory in terms of the expression of $k_{t}^{2}$ in the 2-D model is proposed. Three kinds of electrodes are designed to suppress the transverse mode adjacent to the main mode, including a novel interdigital transducer gap technique that is reported for the first time. With the applicable geometries, these methods reduce the spurious response from 11.8 to <0.5 dB, without significantly affecting the figure of merit of the resonator.

Theoretical analysis of surface acoustic wave propagating properties of Y-cut nano lithium niobate film on silicon dioxide

The surface acoustic wave (SAW) propagating characteristics of Y-cut nano LiNbO3 (LN) film on SiO2/LN substrate have been theoretically calculated. The simulated results showed a shear horizontal (SH) SAW with enhanced electromechanical coupling factor K2 owing to a dimensional effect of the nanoscale LN film. However, a Rayleigh SAW and two other resonances related to thickness vibrations caused spurious responses for wideband SAW devices. These spurious waves could be fully suppressed by properly controlling structural parameters including the electrode layer height, thickness, and the Euler angle (θ) of the LN thin film. Finally, a pure SH SAW was obtained with a wide θ range, from 0° to 5° and 165° to 180°. The largest K2 achieved for the pure SH SAW was about 35.1%. The calculated results demonstrate the promising application of nano LN film to the realization of ultra-wideband SAW devices.

Unexpected, high-Q, low-frequency peaks in seismic spectra

It was established over a decade ago that the normal modes of the Earth are continuously excited at times without large earthquakes, but the sources of the ‘seismic hum’ have remained unresolved. In addition to the normal modes of the Earth, we show spectral lines in seismic data with frequencies which correspond closely to normal modes of the Sun. Moreover, the widths of the low-frequency lines in the seismic spectra are similar to those of solar modes and much narrower than those of the Earth's normal mode peaks. These seismic lines are highly coherent with magnetic fields measured on both the Geostationary Operations Environmental Satellite (GOES)–10 satellite and the Advanced Composition Explorer (ACE) spacecraft located at L1, 1.5 million km sunward of Earth suggesting that the solar modes are transmitted to the Earth by the interplanetary magnetic field and solar wind. The solar modes are split by multiples of a cycle/day and, surprisingly, by the ‘quasi two-day’ mode and other frequencies. Both the phase of the coherences and slight frequency offsets between seismic and geomagnetic data at observatories exclude the possibility that these effects are simply spurious responses of the seismometers to the geomagnetic field. We emphasize data from low-noise seismic observatories: Black Forest (BFO), Piñon Flat (PFO), Eskdalemuir (ESK) and Obninsk (OBN). Horizontal components of seismic velocity show higher coherences with the external (ACE) magnetic field than do the vertical components. This effect appears to be larger near the seismic torsional, or T-mode, frequencies.

A three-dimensional mesh-free model for analyzing multi-phase flow in deforming porous media

Fully coupled flow-deformation analysis of deformable multiphase porous media saturated by several immiscible fluids has attracted the attention of researchers in widely different fields of engineering. This paper presents a new numerical tool to simulate the complicated process of two-phase fluid flow through deforming porous materials using a mesh-free technique, called element-free Galerkin (EFG) method. The numerical treatment of the governing partial differential equations involving the equilibrium and continuity equations of pore fluids is based on Galerkin’s weighted residual approach and employing the penalty method to introduce the essential boundary conditions into the weak forms. The resulting constrained Galerkin formulation is discretized in space using the same EFG shape functions for the displacements and pore fluid pressures which are taken as the primary unknowns. Temporal discretization is achieved by utilizing a fully implicit scheme to guarantee no spurious oscillatory response. The validity of the developed EFG code is assessed via conducting a series of simulations. According to the obtained numerical results, adopting the appropriate values for the EFG numerical factors can warrant the satisfactory application of the proposed mesh-free model for coupled hydro-mechanical analysis of applied engineering problems such as unsaturated soil consolidation and infiltration of contaminant into subsurface soil layers.

Design of millimetre wave diplexers with relaxed fabrication tolerances

A novel millimetre wave waveguide diplexer topology that can be fabricated using relaxed fabrication tolerances is presented. This is achieved by using a highpass filter/hybrid coupler topology in addition to a low order capacitive iris bandpass filter. By targeting the most sensitive centre resonators in the bandpass filter and increasing their length to full wavelength, the sensitivity to fabrication errors associated with changes to the resonator length can be reduced without the introduction of spurious responses close to the passband. The main benefit of this topology is that only one bandpass filter is required to realise the final diplexing response. This is advantageous when tolerance is considered as it is found that resonating structures associated with bandpass filters contribute to tolerance effects. In addition to this, the authors find that the choice of iris discontinuity used to realise the impedance inverters in the bandpass filter can help to relax fabrication tolerances. By subjecting the proposed circuit to a tolerance analysis, simulated results suggest that the circuit can be fabricated with relaxed fabrication tolerances. These discussions are verified with the fabrication of a Ka-band waveguide diplexer, where the measured and simulated scattering parameters are in very good agreement.

Design of Microstrip Triplexer Using Common Dual-Mode Resonator with Multi-Spurious Mode Suppression for Multiband Applications

A triplexer is an important component for channel separation in microwave front-end systems. This paper proposes a triplexers designed with common dual mode resonator sections have been proposed. By exploiting the variable frequency response of the stepped-impedance resonator, resonators can be shared by the three filter channels of the desired triplexer if their fundamental and the first spurious resonant frequency are properly assigned. Triplexer design method for suppressing spurious responses in the stopband by choosing the constitutive resonators with the same fundamental frequency, but staggered higher order resonant frequencies. The design concept is demonstrated by three of third order parallel-coupled bandpass filters. The bandpass filter is composed of three different stepped impedance resonators for which a general design guideline had been provided in order have the same fundamental frequency and different spurious frequencies. The measured results are in good agreement with the simulated predictions, whereby the spurious responses in the upper stopband can be suppressed below-25dB up to 14 GHz, which can be quite useful for multiband and multiservice applications in future wireless communication systems.

이중 급전 구조를 갖는 마이크로스트립 이중 모드 대역통과 필터

In this paper, a microstrip dual mode band pass filter with doubly fed line is proposed. The proposed filter consists of a corner truncated patch with right crossed slots and doubly fed lines. In general, the resonator with the right crossed slots simultaneously has size reduction and spurious response suppression. In order to improve the rejection performance in out of its higher stop band, the dual mode resonator is excited by using doubly fed line. Details of the filter characteristics are described, and both simulated and measured results of the designed filter are presented.

Design of a unit composite right/left-handed cell based bandpass filter with floating slot approach and suppression of spurious using defected microstrip structures

This paper presents the construction of a unit composite right/left-handed cell using hairpin microstrip coupled line circuits. To get the high coupling in comparison to conventional edge coupled microstrip line, the floating slot on the ground plane is used here. Two basic configurations named after short---open---short (SOS) the open---short---open (OSO) model are studied for the realization of band pass filter. The floating ground equalizes the even and odd mode phase velocities and solves the difficulties arises in the fabrication process as it relaxes the requirements on physical dimensions like coupled gaps between lines. The hairpin structure makes the filter structure more compact in size. Defected microstrip structure on the feed line suppresses the spurious response and provides a good stopband performance. Finally a bandpass filter having fractional bandwidth of 70.83 % for OSO model and 44.05 % for SOS model are obtained. Those filters have wide application in modern wireless communication system.

Multilayer multipermittivity ring dielectric resonator antenna filter

ABSTRACTThis article presents a multilayer multipermittivity (MLMP) ring dielectric resonator (DR) which is simultaneously used as a filter and an antenna, hence called dielectric resonator antenna filter. Multiple stacked layer of different permittivity along with the ring feature of DR gives a wideband response for antenna part with improved spurious response. In the presented MLMP ring DR, HEE11 and TE01δ modes are used for antenna and filter element, respectively. As HEE11 and TE01δ are orthogonal in nature that gives an independent control over filter and antenna characteristics. Measurement result reports an impedance bandwidth of 38.06% for dielectric resonator antenna (DRA) covering frequency range from 5 to 7.35 GHz for DRA and 3‐dB bandwidth is 211 MHz covering frequency range from 5.82 to 6.03 GHz for dielectric resonator filter (DRF). The measured resonance frequency is 5.38 and 5.93 GHz of DRA and DRF, respectively. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1147–1152, 2015