Integration Of Filters Research Articles

Development of Substrate-Integrated Waveguide Filters for Low-Cost High-Density RF and Microwave Circuit Integration: Direct-Coupled Cavity Bandpass Filters With Chebyshev Response

Direct-coupled cavity bandpass filters with Chebyshev response are studied and realized, using the technique of planar substrate-integrated waveguide (SIW) for the purpose of high-density integration and cost reduction. Using a general mode-matching technique, the scattering matrix of waveguide bifurcation-type discontinuity and asymmetric iris are established and analyzed. Such discontinuities are used as coupling components and building blocks in the design of filters that are realized on RT/duroid 6002 with the ordinary printed circuit board process in our work. Measurement for one of the three four-pole filters gives 3.4 dB insertion loss and 17 dB return loss over the whole passband at near 24 GHz ( $K$ -band) with 440-MHz bandwidth (1.8%). The design method can be widely adopted for the development of microwave-integrated circuits, and the mass-fabrication of such SIW filters can be made easy while maintaining a very low cost.

Propagation properties of the graphene surface plasmon in comb-like waveguide

We investigate theoretically the electromagnetic propagation properties of graphene plasmons in a comb-like dielectric-graphene-dielectric (DGD) waveguide. The effective index of surface plasmon mode supported by the waveguide is analysed numerically, and it is found that the effective refractive index increases with the refractive index of the dielectric and decreases with Fermi energy of the graphene sheet. For a comb-like DGD waveguide with a finite branch length, a subwavelength plasmon filter can be formed by Fabry-Perot resonance caused by the reflection of the guided mode at the branch. The central frequencies of the gaps can be changed by varying the length of the branch, Fermi energy, the refractive index of the dielectric and the layer number of graphene sheets. The analytic and simulated result reveals that a novel nanometric plasmonic filter in such a comb-shaped waveguide can be realized with ultracompact size in a length of a few hundred nanometers in the mid-infrared range. We find that the frequencies of the stopband increase with Fermi energy and the layer number of graphene sheets, while will they decrease nonlinearly with the length of the branch and the refractive index of the dielectric. In addition, the width of the gap can be increased with the number of comb branches. Such electromagnetic properties could be utilized to develop ultracompact photonic filters for high integration.

A REVIEW ON RECONFIGURABLE INTEGRATED FILTER AND ANTENNA

In the past few years, several satisfying various objectives and designs of reconfigurable integrated microwave filter and antenna have been proposed for wireless communication systems. Several designs are new concepts and techniques, whereas others are inspired from previous works. The improvement concepts of these designs can be reviewed from this compilation of studies. This paper begins with an explanation of the reconfigurable filter, reconfigurable antenna and reconfigurable integrated microwave filter and antenna, followed by discussion on several designs in terms of size, measurement, performance and technology used. Among various designs, reconfigurable on planar structures are extensively used because of their simple design procedures and easy to tune on the desired frequency, bandwidth and attenuation. Most of the existing studies are focusing tunable on single element, i.e. either on filter or antenna side; however, it limits the tunable range and flexibility of the filtering antenna response. An alternative design of filtering antenna can be suggested to produce reconfigurable tuning capabilities on both microwave filter and antenna to produce overall good performance for multifunction operation in RF/microwave applications.

Improved droop control strategy for grid-connected inverters

Abstract An improved control strategy for grid-connected inverters within microgrids is presented in this paper. The strategy is based on the classical P − ω and Q − V droop method. The improvement in the proposed control strategy is twofold: Firstly, the transient response of the droop controller is improved by replacing the traditional method of measuring average power, which is based on using a first order low pass filter, by a real time integration filter. This is shown to reduce the imported transient energy when connecting to the grid. Secondly, the steady state output current quality is improved by utilising a virtual inductance, which is shown to reject grid voltage harmonics disturbance and thus improve the output current THD. A small signal model of the inverter based on the transfer function approach is developed to analyse its stability and determine droop gains. Simulation and experimental results are presented to validate the model and demonstrate the controller capabilities.

On the estimation of the structural index from low-pass filtered magnetic data

The estimation of the structural index and of the depth to the source is the main task of many popular methods used to analyze potential field data, such as Euler deconvolution. However, these estimates are unstable even in the presence of a weak amount of noise, and Euler deconvolution of noisy data leads to an underestimation of structural index and depth. We have studied how the structural index and depth estimates are affected by applying low-pass filtering to the data. Physically based low-pass filters, such as upward continuation and integration, have been shown to be the best choice over a range of altitudes (upward continuation) or orders (integration filters), mainly because their outputs have a well-defined physical meaning. In contrast, mathematical low-pass filters require that the filter parameters be tuned carefully by means of several trial tests to produce optimally smoothed fields. The C-norm criterion is a reliable strategy to produce a stabilized vertical derivative, and we discourage Butterworth filters because they tend to a vertical integral filter, for a high cutoff wavenumber, thus complicating the interpretation of the estimated structural index. We found that the estimated structural index and depth to source increase proportionally with the amount of smoothing, unless in the case of overfiltering. In that case, the severe distortion of the original field may cause a decrease of the estimated structural index and depth to source.

Effect of the order of fractional integration on impulse responses

For a fractional time series model integrated of order d we derive two results. First, it is obtained how a change in d affects the coefficients of the integration filter. For long memory (d>0), the effect is always positive; in the case of anti-persistence (d<0) the effect may be positive or negative depending on d. Second, those results are extended to the sequence of autocorrelations for fractionally integrated noise.

Hierarchical Operation of Water Level Controllers: Formal Analysis and Application on a Large Scale Irrigation Canal

We introduce a hierachical controller, the purpose of which is to speed up the water delivery process as compared to the standard method applied currently in the field. The lower layer of the hierarchical control consists of local proportional integral filter controllers (PIF controllers) for upstream control at each gate; specifically they are proportional integral controllers with a low-pass filter. In contrast, the higher layer is composed of a centralized model-based predictive controller, which acts by controlling the head gate and by coordinating the local PIF controllers by modifying their setpoints when needed. The centralized controller is event-driven and is invoked only when there is a need for it (a water delivery request) and as such it contributes scarcely to the communication burden. The scheme is robust to temporary communication losses as the local PIF controllers are fully able to control the canal in their normal independent automatic upstream control mode until the communication links are restored. We discuss the application of the hierarchical controller to a precise numerical model of the Central California Irrigation District Main Canal. This shows the improved performance of the new hierarchical controller over the standard control method.

Generalization of integral filters in BL-algebras and n-fold integral BL-algebras

In this paper, we introduced the notion of \(n\)-fold integral filters in \(BL\)-algebras and we stated and proved some theorems, which determine the relationship between this notion and other types of \(n\)-fold filters in \(BL\)-algebras. Moreover, we introduce the notions of \(n\)-fold integral \(BL\)-algebras and \(n\)-fold obstinate \(BL\)-algebras. Also, we show that \(n\)-fold implicative basic logic is not Godel logic in general and in follow, we prove that a \(BL\)-algebra \(L\) is an \(n\)-fold obstinate \(BL\)-algebra if and only if \(L\) is an \(MV\)-algebra and the order of every element \(1\ne x\) is equal to \(n\) if and only if \(L\) is an \(MV\)-algebra and \(n\)-fold integral \(BL\)-algebra.

A Krein Space Approach to $H_{\infty}$ Filtering of Discrete-Time Nonlinear Systems

In this paper, a Krein space approach to finite horizon H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> filtering is proposed for a class of affine nonlinear discrete-time systems. It is shown that the problem of H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> nonlinear filtering can be converted into a minimum of an indefinite quadratic form. Hence, a relationship between H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> nonlinear filter in Hilbert space and nonlinear estimation in Krein space is established. By using first-order Taylor approximation and Krein space projection, a sufficient and necessary condition for the minimum is derived. Moreover, a feasible solution of the H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> nonlinear filter can be obtained by recursively computing Riccati recursions. Finally, a numerical example and one kind of integration filter are used to demonstrate the effectiveness of the proposed method.

Integrated color filter and polarizer based on two-dimensional superimposed nanowire arrays

A two-dimensional nanowire array with asymmetric lattices was investigated. The orthogonal arrays were fabricated by two-step interference lithography, with 300 nm-pitch arrays overlying the 1000 nm-pitch. Due to the peculiar structure, the properties of the top two-dimensional structure and bottom 1000 nm gratings are superposed. With incidence angles smaller than 30°, short wavelengths of visible light for both transverse electric (TE) and magnetic (TM) polarizations are transmitted as a color filter. For larger incident angles, TE light transmission decreases monotonously, while distinct tunneling of TM light surface plasmon resonance was observed, leading to an integrated polarizer and color filter effect. The experimental results, theoretical calculation, and numerical simulations are in good agreement. The comprehensive characters resulted from the aforementioned mechanisms indicate a new approach to fabricate integrated color filter and polarizer with potential in liquid crystal display, optics communication, and laser applications.

Performance analysis of WDM-PON architecture using different receiver filters

In this paper the performance effect of a 40Gb/s Wavelength-Division-Multiplexed Passive Optical Network (WDM-PON) is analyzed using different receiver filters namely Integrator filter, Bessel filter, Butterworth filter, Chebyshev filter, Inverse Chebyshev filter, Elliptic filter, Gaussian filter and Rectangular filter. The data rate and channel spacing are taken as 10Gb/s per channel and 100GHz, respectively. Among all the investigated filters, Bessel filter is considered to be the best one for WDM-PON network by the obtained BER and Q factor values.

PERFORMANCE OF FILTERS USED IN MODERN IRRIGATION NETWORK

Dual Irrigation Filter, as new integral filter, was developed, it has the ability to filter water regardless the particles specific gravity and without fear of screen clogging. The new filter is locally manufactured with combination between the sand separator and screen filter. The dual irrigation filter was developed to have dual of application; as irrigation filters with a closed sedimentation tank, and as an alternative for the sedimentation pool with opened underflow to the atmosphere. With opened and closed underflow apex, the dual irrigation filter was tested to estimate and evaluate the filtration efficiency and outflow rate under different operation parameters. Three levels of feed suspension concentration (600, 1500 and 2400 ppm) prepared by using a coarse sandy loam soil sample, two levels of different operating pressure (2.5 and 4.0 psi) and three levels of the screen filtration degree (100, 150 and 200 mesh), were selected for the test. With opened underflow apex, the highest mean of the filtration efficiency for the feed suspension of 600, 1500, 2400 ppm were 0.46205, 0.42126 and 0.38719, respectively, for the different operating pressure of 4.0 and 2.5 psi were 0.46205 and 0.44135, respectively, and for the screen filtration degree of 100, 150 and 200 mesh were 0.42855, 0.45515 and 0.46205, respectively, whereas, with closed underflow apex, the highest value of the filtration efficiency for the feed suspension of 600, 1500, 2400 ppm were 0.4479, 0.3985 and 0.3601, respectively, for the different operating pressure of 4.0 and 2.5 psi were 0.4479 and 0.4258, respectively, and for the screen filtration degree of 100, 150 and 200 mesh were 0.4100, 0.4367 and 0.4479 respectively. The outflow rate was just statistically correlated to the different operating pressure; and in the case of opened apex, the highest mean of the outflow rate for the different operating pressure of 4.0 and 2.5 psi were 8.678 and 4.977 m3/h, respectively, whereas, in the case of closed apex, they were 9.345and 5.613m3/h, respectively.

Measuring Method and Device Microwave Cavity System Temperature Control Factor

A new measuring method and device were proposed in this paper. It is about the cavity bubble system temperature control factor. It provides reference for research workers in this field. The method is applied in the passive atomic clocks technology, especially the integration filter resonance absorption cavity system temperature control technology.

Direct Navigation Mode and Indirect Navigation Mode for Integrated SINS/GPS

There are two options for the state estimation procedure by the integration filter for the integrated SINS/GPS, namely: direct navigation mode and indirect navigation mode. Determining which one of the two navigation modes will be more celebrated than the other under different conditions is an important but so far less seriously treated issue. The two navigation modes were systematically studied in terms of the system model, filtering algorithm and application issues. The car-mounted experiments were carried out to compare two navigation modes under different road conditions. The results show that direct navigation mode performs indirect navigation mode in terms of accuracy and stability. However, indirect navigation mode has low calculation burden and simple filter design.

Enhanced optical transmission in a plasmonic nanostructure perforated with compound holes and nanorods

We propose a novel enhanced optical transmission plasmonic nanostructure composed of a metallic film perforated with a compound rectangular hole and nanorod array. The optical characteristics are investigated by the three-dimensional finite-difference time-domain (FDTD) method. An extraordinary enhanced transmission (transmittance over 96%) in the optical regime is obtained as a result of the excitation and hybridization of localized surface plasmon resonances (LSPRs), surface plasmon polaritons (SPPs), as well as the gap plasmon modes supported by the holes. The enhanced optical transmission can be effectively tailored by changing the geometrical parameters such as the length and width of inner cubic Ag nanorods, the gap of rectangular holes, the period of compound hole array, as well as the height of Ag film due to their effects on oscillating charges on metal surfaces. The structure could facilitate numerous important applications in highly integrated plasmonic filters and optoelectronic circuits.

Adaptive integral filter for the identification of two-input two-output processes

Measurement noise and loop interaction introduce errors during the identification of a two-input two-output (TITO) process. This paper proposes a novel method for the identification of a TITO process in the presence of measurement noise and loop interaction. The proposed structure includes two preload relays (P_relays) in the forward paths and two adaptive integral filters in the feedback paths to induce the limit cycle outputs. The integral filters are designed adaptively during the identification. The integral filters in the feedback paths reduce the interaction between the loops and induce denoised limit cycle outputs. Then a pair of parametric transfer function models for the TITO process dynamics is obtained using the limit cycle information. Also, a new approach to estimate the steady state gains of the models is proposed. Simulation examples illustrate the effectiveness and the simplicity of the proposed identification and control method.

Quasi-Stochastic Integration Filter for Nonlinear Estimation

In practical applications, numerical instability problem, systematic error problem caused by nonlinear approximation, and nonlocal sampling problem for high-dimensional applications, exist in unscented Kalman filter (UKF). To solve these problems, a quasi-stochastic integration filter (QSIF) for nonlinear estimation is proposed in this paper. nonlocal sampling problem is solved based on the unbiased property of stochastic spherical integration rule, which can also reduce systematic error and improve filtering accuracy. In addition, numerical instability problem is solved by using fixed radial integration rule. Simulations of bearing-only tracking model and nonlinear filtering problem with different state dimensions show that the proposed QSIF has higher filtering accuracy and good numerical stability as compared with existing methods, and it can also solve nonlocal sampling problem effectively.

Sensored Field Oriented Control of a Robust Induction Motor Drive Using a Novel Boundary Layer Fuzzy Controller

Physical sensors have a key role in implementation of real-time vector control for an induction motor (IM) drive. This paper presents a novel boundary layer fuzzy controller (NBLFC) based on the boundary layer approach for speed control of an indirect field-oriented control (IFOC) of an induction motor (IM) drive using physical sensors. The boundary layer approach leads to a trade-off between control performances and chattering elimination. For the NBLFC, a fuzzy system is used to adjust the boundary layer thickness to improve the tracking performance and eliminate the chattering problem under small uncertainties. Also, to eliminate the chattering under the possibility of large uncertainties, the integral filter is proposed inside the variable boundary layer. In addition, the stability of the system is analyzed through the Lyapunov stability theorem. The proposed NBLFC based IM drive is implemented in real-time using digital signal processor (DSP) board TI TMS320F28335. The experimental and simulation results show the effectiveness of the proposed NBLFC based IM drive at different operating conditions.

능동 자기예압 공기베어링 스테이지의 진동감쇠 제어

In this paper, we proposed an air bearing stage with active magnetic preloads in vertical directions compensating motion errors and attenuating vibrations to improve dynamic characteristics. This preloaded design gives simpler configuration of the stage, and active control of preload can be used for compensating motion errors by feedforward method. To improve dynamic characteristics, vibration of the table is monitored by an accelerometer, and controlled by a DSP based digital controller with integrator and band pass filters for suppressing roll and pitch vibration modes. The modes were evaluated by measuring frequency response functions, and compared with compensated responses. This showed effective results for suppressing poorly damped regenerative vibration of air bearings.

A Bi-Parametric Clutter-Map CFAR Detection Method in Non-Gaussian Environment for Foreign Objects Debris on Runways

Time-varying land clutter is primary interference for Foreign Objects Debris (FOD) detection on airport runways. Traditional clutter-map CFAR (CM-CFAR) algorithms were ineffect-ive to detect targets in non-Gaussian clutter. In this paper, a Bi-parametric CM-CFAR (Bi-CM-CFAR) algorithm based on bi-parameters estimation is proposed. Clutter-level estimation is obtained with video integrator, parameters estimator and recursive filter; and updated in each scanning period. Moreover, simulations verify effectiveness of this method for FOD detection.