Filter Dimensions Research Articles

Phase Velocities Equalization of Coupled Microstrip Lines Using $\Omega$-Shaped Particles and Suppression of the Second Harmonic

This paper represents a new technique for equalization of phase velocities in coupled microstrip lines using <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\Omega$</tex> </formula> -shaped particles. In the first step, the initial idea is investigated by considering a homogenized model for the substrates, and the structure is analyzed using a developed numerical code. This analysis provides an overview in finding the proper orientation of the particles as well as examining the pseudochirality effect. It is demonstrated that placing the omega particles in a specific orientation inside the substrate leads to a remarkable increase in the phase velocity of odd modes and can provide the phase velocities equalization. In the second step, the proposed structure is simulated with few numbers of particles. The results confirm the considered effective medium for the substrate and the presented physical explanations. The dispersive characteristics of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\Omega$</tex></formula> particles found to be valuable in proposing a simple and yet efficient method for designing coupled line filters. This procedure is based on finding the dimensions of a conventional filter with a narrower bandwidth than the desired one. In order to validate the effectiveness of the proposed method, a third order Chebychev filter is designed on FR4 substrate and a suppression level higher than 60 dB is achieved. Finally, the proposed structure is fabricated and it is observed that the experimental results are in good agreement with the simulated data.

Elliptic high-pass filters with stepped impedance resonators in coplanar waveguide technology

Ultra compact elliptic-function high-pass filters (HPFs) in coplanar waveguide (CPW) technology are presented.The required shunt-connected series resonators of the elliptic-function response are implemented by means of stepped impedance resonators (SIRs), etched in the back substrate side. The accurate circuit model of the filter, including parasitic effects, is presented and used for design purposes. An order-3 prototype HPF with 0.1-dB ripple and 3-GHz cutoff frequency is designed and fabricated as proof-of-concept demonstrator. The measured filter response is in good agreement with the ideal elliptic-function in the region of interest. Filter dimensions are as small as 0.092λg × 0.185λg, λg being the guided wavelength at the cutoff frequency. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1094–1097, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26692

A fast design approach of compact microstrip multiband bandpass filters

AbstractA simplified technique is used to design multiband bandpass filters using a compact ultrawideband (UWB) microstrip bandpass filter with spiral‐shaped λg/2 resonators, spaced apart by λg/4.Pairs of transmission zeros are generated on predefined locations in the UWB to create dual‐, triple‐, or quad‐band bandpass filters, as desired. The bandwidth and location of the sub‐bands can be easily controlled by the locations of the transmission zeros. These are generated by inserting additional resonators with predicted lengths. Highly selective quasielliptic multiband controllable responses can be achieved. Equations for fast calculations of filter dimensions are derived. Measurements show excellent agreement with the simulations. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1075–1079, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26742

Application of 2D surface ERT to on-site wastewater treatment survey

Abstract Interest in the functioning of on-site wastewater treatment in rural areas has grown both among authorities and private companies in France and elsewhere in Europe. This is partly due to the enforcement of a new law that obliges communities to control on-site wastewater treatment systems. For extensive systems—mostly Vertical Flow Sand Filters (VFSF)—the introduction of this law revealed the absence of reliable methods to assess if a system was built according to recommendations and is operating well. The aim of this paper is to examine whether surface Electrical Resistivity Tomography (ERT) is a reliable method for mapping outline of filter dimensions and reveal clogging effects. Using forward modeling of synthetic models, we created sensitivity maps of ideal resistivity maps revealing that the method is well-suited to outline the horizontal extent of the filter but not necessarily its constitutive layers because the coarse gravel layer near the surface reduces the sensitivity to features below this layer. Hence whatever the geophysical signal is produced by clogging, this will be difficult to detect. The most appropriate inversion procedure, i.e. the L 1 -norm inversion, reveals the filter extent with an error less than the electrode spacing independent of noise levels. Finally, the procedure is illustrated for a real case ERT survey on a full scale VFSF. This study reveals that simple surface ERT measurements provide a good estimate of the filter area, but additional methods are required for more detailed vertical analysis including potential detection of clogging effects.

Miniaturised bandpass filter using dumb-bell-shaped slot resonator

A microstrip dumb-bell-shaped slot resonator (DSSR) is proposed for a miniaturised bandpass filter (BPF) design. An equivalent circuit model of the DSSR is also presented and validated through circuit and EM simulations. The proposed DSSR does not employ ground slots, so the fabrication process is simple. This ultimately results in an easy analysis and design which minimises fabrication errors. Using the DSSR, a miniaturised 7.35 GHz BPF is designed and tested. The filter dimensions are 0.37λg×0.27λg, where λg is the guided wavelength at the centre frequency of 7.35 GHz.

Compact Wideband CPW Bandpass Filters With Transmission Zeros Based on Stepped Impedance Resonators (SIR)

Compact wideband and highly selective bandpass filters (BPFs) implemented in coplanar waveguide technology are presented. The high frequency selectivity is achieved by the presence of shunt-connected stepped impedance resonators which introduce a transmission zero at both band edges. The circuit model of the filter as well as the design procedure to synthesize the required bandwidth, based on such model, is presented. An order-3 prototype BPF with 38% fractional bandwidth, central frequency fo = 6.3 GHz and 0.03 dB bandpass ripple is designed and fabricated as proof-of-concept demonstrator. The measured filter response is in good agreement with the model predictions. Filter dimensions are as small as 0.16λ0 × 0.29λ00 , λ0 being the free-space wavelength at the central filter frequency.

Small-sized microstpip delay line filters on the substrates with high permittivity

There are considered small-sized microstrip delay line filters on the substrates with permittivity (ɛr = 92, 36), whose metallic screen is placed at the height, equal to substrate thickness. Filters contain three step resonators, which are placed close to each other with a gap of 0.1–0.2 mm. The basis of delay line filters construction lies in specificities of electromagnetic interaction of closely placed step resonators with closely placed screen and possibility of modification of coupling between non-adjacent resonators. There are represented data of measurement and simulation. Dimensions of a filter on a substrate with ɛr = 92, was 5×5×2 mm, they are comparable with dimensions of small-sized microwave ceramic filters of one-piece construction, used in portable communication devices. It is shown that a set of technical characteristics makes new delay line filters competitive.

LTCC ultra wide band filter

This article presents the analysis of ultra wide band (UWB) filter designed using a symmetrical three parallel coupled line resonator in low temperature co-fired ceramic (LTCC) medium. The ground plane with an aperture incorporated in it improves the coupling. Based on circuit models, the designed UWB filter has been analyzed, and the results have been confirmed by experiments. The filter has been realized with Dupont LTCC tape DuPont 951 (that has dielectric constant of 7.8). Maximum insertion loss of the experimental filter is 1.5 dB. The group variation over the pass band of the filter is within 0.2 ns. Dimensions of the experimental LTCC filter are 20 × 10 × 0.72 mm. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2580–2583, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26311

Development and validation of a hybrid simulation technique for cone beam CT: application to an oral imaging system

This paper proposes a hybrid technique to simulate the complete chain of an oral cone beam computed tomography (CBCT) system for the study of both radiation dose and image quality. The model was developed around a 3D Accuitomo 170 unit (J Morita, Japan) with a tube potential range of 60–90 kV. The Monte Carlo technique was adopted to simulate the x-ray generation, filtration and collimation. Exact dimensions of the bow-tie filter were estimated iteratively using experimentally acquired flood images. Non-flat radiation fields for different exposure settings were mediated via ‘phase spaces’. Primary projection images were obtained by ray tracing at discrete energies and were fused according to the two-dimensional energy modulation templates derived from the phase space. Coarse Monte Carlo simulations were performed for scatter projections and the resulting noisy images were smoothed by Richardson–Lucy fitting. Resolution and noise characteristics of the flat panel detector were included using the measured modulation transfer function (MTF) and the noise power spectrum (NPS), respectively. The Monte Carlo dose calculation was calibrated in terms of kerma free-in-air about the isocenter, using an ionization chamber, and was subsequently validated by comparison against the measured air kerma in water at various positions of a cylindrical water phantom. The resulting dose discrepancies were found <10% for most cases. Intensity profiles of the experimentally acquired and simulated projection images of the water phantom showed comparable fractional increase over the common area as changing from a small to a large field of view, suggesting that the scatter was accurately accounted. Image validation was conducted using two small phantoms and the built-in quality assurance protocol of the system. The reconstructed simulated images showed high resemblance on contrast resolution, noise appearance and artifact pattern in comparison to experimentally acquired images, with <5% difference for voxel values of the aluminum and air insert regions and <3% difference for voxel uniformity across the homogeneous PMMA region. The detector simulation by use of the MTF and NPS data exhibited a big influence on noise and the sharpness of the resulting images. The hybrid simulation technique is flexible and has wide applicability to CBCT systems.

EM 시뮬레이션 기반 다중 포트 Y-파라미터를 이용한 변위된 인터디지털 여파기 설계

In this paper, we present a design of a 5th order Chebyshev interdigital band-pass filter using inverter and susceptance slope parameter values obtained from EM simulated multi-port Y-parameters. The shifted length of the resonator is determined when the frequency of the transmission zero is separated far away from the center frequency. For the initial dimensions of the interdigital filter, the filter is decomposed into the individual resonators, and the dimensions are obtained using EM Simulation of the decomposed resonators. However, the interdigital filter with the dimensions determined from the EM simulation of the decomposed resonators shows slightly distorted response from the desired frequency response due to the coupling between non-adjacent resonators. To obtain a EM simulation dataset, EM simulation for this filter is carried out by parameter sweep with constant ratio for the initial values. In this dataset, it is determined the final values for the filter by optimization. The fabricated filter by PCB shows an upper-shift of center frequency of about 70 MHz, which was caused by permittivity changed and tolerance of fabrication.

Design and analysis of plasmonic filters based on stubs

In this study, we describe characteristics of plasmonic filters based on stubs coupled perpendicularly to metal–insulator–metal waveguides. To achieve a desirable filter, a designing procedure is proposed based on impedance curves, which lead to responses with great accordance to those obtained by numeric techniques. We study the impact of stub lengths and distance between stubs on bandgap width and filter sharpening. In addition, we illustrate the existence of trade-off between filter dimensions and filter parameters, which lead to a discussion about advantages and disadvantages of these structures. Validation of analytic results is confirmed with the finite-difference time-domain method.

PERFORMANCE ANALYSIS OF TDLMS FILTER FOR IMAGE ENHANCEMENT

In this study, the filtering performance of adaptive image noise filter based Two Dimensional Least Mean Squares (TDLMS) method was analyzed experimentally. For this purpose, an interface realizing the method was used to investigate the effect of the initial values, step size, and filter dimensions on performance. Comparative evaluations of the performance of the algorithm for test parameters were presented both visually and numerically. The experimental results show that the filtering performance is increased for high noise levels, while it is degraded for lower noise levels.

State estimation for discrete linear systems with observation time-delayed noise

State estimation problem is discussed for discrete-time systems with delays in measurement noise sequence, which isusually seen in network control and geophysical prospecting systems. An optimal recursive filter is derived via stateaugmentation. Dimensions of the optimal filter just are the sum of dimensions of state and observation vector.Therefore, they are not related to the size of delay. Besides, a sub-optimal recursive filter with same dimension asthe original state is designed. The sub-optimal filter realizes instant optimization at current time. One exampleshows the effectiveness of the proposed approach.

Three-dimensional void space structure of activated carbon packed beds

The three-dimensional void space structure generated by piling active carbon grains has a large impact on the filter operation, through the modification of the transport properties inside the bed. To gain insight into the relation between morphology and transport properties, the three-dimensional void space structure of activated carbon packed beds was studied by X-ray microtomography coupled with image analysis. Image analysis algorithms allowing the determination of the total void fraction, the void size distribution and the radial void fraction profiles were developed. This methodology was used to characterize the void space structure of two filters with the same length but different diameters, 15 and 28 mm. Commercial granular activated carbon with average particle size close to 1 mm was used. The comparison of the void size distributions indicated that void sizes are almost normally distributed around only one maximum for the large filter, while the distribution has a more complex shape in the small filter. The radial void fraction profiles showed an increase of the void fraction from the center of the filter to the wall accompanied with an oscillatory behaviour at the small scale. Power spectrum of radial profiles of the large filter shows a characteristic length matching well with the carbon particle size, indicating that the carbon grains are uniformly packed in the bed. In the small filter, power spectrum suggests an uneven packing of grains. For both filters, the total void fraction measured by image analysis was very close to the value determined ‘physically’ knowing the carbon mass, bulk density and filter dimension.

Synthesis of Star-Junction Multiplexers

This paper illustrates a general approach to the synthesis of microwave multiplexers (RF combiners) presenting a star-junction topology (with a resonating junction). The channel filters composing the multiplexer can be arbitrarily specified; in particular, the attenuation characteristic may include transmission zeros (imaginary and/or complex). The synthesis procedure, developed in a low-pass frequency domain (suitably defined), is based on an iterative algorithm which evaluates the characteristic polynomials of both the overall multiplexer and the composing filters. Using these latter polynomials, the normalized coupling matrices of the filters can be computed using one of the methods available in the literature and the dimensioning of the channel filters is carried out through the usual de-normalized parameters (coupling coefficients and external <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> ). The detailed design steps illustrating the synthesis of a triplexer for base stations of mobile communications are presented. The designed device was then built, and the comparison between measurements and simulations has validated the new synthesis approach.

Compact Elliptic-Function Coplanar Waveguide Low-Pass Filters Using Backside Metallic Patterns

In this letter, compact elliptic-function low-pass filters (LPF) implemented in coplanar waveguide technology by etching stepped impedance resonators (SIR) in the back substrate side, are presented. The required transmission zeros of the elliptic-function response are provided by the shunt connected SIRs. As an illustrative example, an order-3 prototype LPF with 1 GHz cutoff frequency is designed and fabricated. The measured stop-band rejection is better than 30 dB up to 6.4 GHz, and a narrow transition band is obtained. To demonstrate the possibilities of the approach to synthesize arbitrary elliptic-function responses and order, a fifth-order elliptic LPF with 1 GHz cut-off frequency is also designed and fabricated. Filter dimensions are as small as 6.6 mm × 9.2 mm, i.e, 0.034λ × 0.047A, for the third-order filter, and 12.1 mm × 13 mm (0.062λ × 0.067λ) for the fifth-order filter, λ being the guided wavelength at cutoff.

Accurate Synthesis and Design of Wideband and Inhomogeneous Inductive Waveguide Filters

In this paper, a new synthesis and design methodology is presented and applied for the fast and accurate design of inductive rectangular waveguide filters. By using this technique, the dimensions of both homogeneous and inhomogeneous filters can be successfully synthesized for almost any practical filter bandwidth, return loss, or filter order. This novel technique is based on a prototype with additional degrees of freedom, able to match the response of the different filter components in a wideband frequency range, and an elaborated design procedure that fully exploits this flexibility. During the design procedure, the prototype and the real structure are continuously aligned in order to have the same electromagnetic behavior and jointly evolve to obtain an equiripple response. Once the final prototype has been synthesized, excellent filter dimensions can be extracted that, in most cases, do not require further optimization. Examples will show the outstanding performance of the proposed design technique in terms of versatility, accuracy, and CPU time.

E-Plane Band pass Filter With Resonators of Different Cutoff Frequencies

يتضمن البحث الى تحسين عمل مرشحات عرض الحزمة المايكروية في نطاق القطع بواسطة ادخال قطع معدنيةعلى محور موجه الموجات حيث اتضح ان المرشح المقترح يؤدي الى تحسين في العمل ضمن نطاق القطع اضافة الى تقليل ابعاد المرشح مقارنة بمرشحات عرض الحزمة المألوفة.

Evaluation of respiration parameters in a few generations and clones of Simocephalus vetulus (Crustacea, Cladocera) under controlled conditions

Cladocera use their thoracic filter limbs, animated by rhythmic and persistent movements, for food collecting and gas exchanges. Several researches have been performed on Daphnia magna in natural environments and in laboratory to identify the adaptations developed toward a decrease or a lack in oxygen. However, no experiment was performed on cladocerans living exclusively in littoral areas, which need efficient adaptations to survive an always changing environment especially regarding oxygen concentration. These changes require from organisms that they spend additional energy in order to satisfy their need in oxygen. The present laboratory experiments were based on a typical inhabitant of littoral areas, Simocephalus vetulus, and on individuals which came directly from natural environments. Respiration rate and NADH fluorescence in filter limb muscles, as a marker of tissue oxygenation, were analysed on 20 families distributed over five generations, all acclimated and cultured under constant food supply conditions. The results underlined differences among generations especially due to body dimensions, and consequently to filter dimensions. As opposed to our former hypothesis, small and young individuals appeared to be more active and thus display a more efficient respiration than big and old Simocephalus.

Approach of Metamaterial-Based Quarter-Wave Resonator and Its Application to Very Compact LTCC Bandpass Filter

In this paper, a resonator based on composite right/left handed transmission line concept is discussed. This resonator excites -1st order resonance mode. We start with half-wave resonators consisting of two unit cells of a composite right/left handed transmission line. From the simulated field distributions, the center of these half-wave resonators can be short-circuited to obtain a quarter-wave resonator in the -1st mode. Susceptance slope parameters are calculated for the resonator. Then this resonator is applied for a 2-pole filter made by LTCC, which can be designed with standard filter design theory owing to the slope parameter. The dimension of the experimental filter implemented by LTCC is 2.5mm by 1.35mm by 0.52mm. The insertion loss is 1.80dB at the 2.4GHz band. Good agreement between measured and computed results is obtained.