A simple and compact filter structure for lowpass and dual-band bandpass response with controllable transmission zeros/center frequencies/3-dB bandwidth is proposed in this brief. The proposed filter ...structure uses two-unit cells, which contains λ/5 length of folded coupled line and open circuited L-shape strip. A lowpass and a bandpass response has been realized by a unit cell due to formation of LC series and shunt tank circuit. Another bandpass response has been achieved by connecting two-unit cells with a strip. In literature, there are very few designs which can achieve two different type of filtering responses. The proposed design is compact as compared to the state-of-the-art and also the two filtering responses have been achieved with improved selectivity and impedance matching due to formation of additional tank circuit. The size of the filter excluding feed line is 0.13λ g × 0 .06λ g × (15.5 mm × 7.2 mm) at the 3-dB cut-off frequency (1.05 GHz) of the lowpass filter. The position of transmission zeros/center frequencies and 3-dB bandwidth characteristics can be separately controlled by varying the physical parameter of designed filter structure. The filter performance has been validated through electromagnetic simulation and experimental measurements. The metamaterial properties of designed filter has been verified by its dispersion diagram.
This brief reports on the RF design and practical development of a non-reciprocal balanced bandpass filter (BPF) that exhibits a highly-selective quasi-elliptic response in the forward direction of ...propagation that is shaped by four transmission poles and two transmission zeros (TZs). By modulating some of the filter's resonators with phase-progressed AC signals, a non-reciprocal response is obtained in the differential mode. Its common-mode is also highly suppressed due to the incorporation of a balanced network that results in two additional TZs and resistive loss that are unique to the common-mode. The filter order can be increased by cascading additional resonators. For validation purposes, a microstrip prototype centered at 725 MHz was designed, manufactured, and measured. It showed a high isolation in the differential-mode reverse transmission of up to 62.1 dB. Moreover, the common-mode was suppressed by over 45 dB in a bandwidth greater than one octave.
The cascaded-resonator (CR)-based filter structure has been proposed in previous works as a convenient approach to the dynamic harmonic analysis. This CR filter can be with multiple resonator (MR) ...poles or ones dispersed properly. In all previous papers the resulting filters of the CR structure are finite-impulse-response (FIR)-type. In this letter, the aim is to use the infinite-impulse-response (IIR) CR-based filters for a full spectrum estimation. Thanks to the linearized model, including stability conditions, filter coefficients of the IIR filter transfer function are derived through the minimax optimization using a linear programming. This way, the frequency responses of the harmonic analyzer can be improved in accordance with actual requirements, sometimes even without any increase of computational burden.
Accurate information about dynamic states is important for efficient control and operation of a power system. This paper compares the performance of four Bayesian-based filtering approaches in ...estimating dynamic states of a synchronous machine using phasor measurement unit data. The four methods are extended Kalman filter, unscented Kalman filter, ensemble Kalman filter, and particle filter. The statistical performance of each algorithm is compared using Monte Carlo methods and a two-area-four-machine test system. Under the statistical framework, robustness against measurement noise and process noise, sensitivity to sampling interval, and computation time are evaluated and compared for each approach. Based on the comparison, this paper makes some recommendations for the proper use of the methods.
A novel domain for Index Modulation (IM) named "Filter Domain" is proposed. This new domain generalizes many existing modulations and IM domains. In addition, a novel scheme "Filter Shape Index ...Modulation" (FSIM) is proposed. This FSIM scheme allows a higher Spectral Efficiency (SE) gain than the time and frequency IM dimensions in Single-Input Single-Output (SISO) systems. In the FSIM system, the bit-stream is mapped using an Amplitude Phase Modulation (APM) as QAM or PSK, and an index of a filter-shape changing at the symbol rate. This filter shape, being changed at each symbol, enables a SE gain in SISO system without sacrificing any time or frequency resources. Compared to an equivalent 8QAM and 16QAM schemes and at the same SE, the FSIM with QPSK using 2 and 4 non-optimal filter shapes achieves a gain of 3.8 dB and 1.7 dB respectively at BER= 10 −4 , and this superiority is maintained in frequency selective fading channel compared to equivalent SISO-IM schemes. A low complexity detection scheme, approaching the maximum likelihood detector performance, is proposed along with a full performance characterization in terms of theoretical probability of filter index error and BER lower bound. Finally, FSIM can achieve better spectral and energy efficiencies when a filter bank and an ISI cancellation technique are optimally designed.
In this thesis, the use of voltage-source active filters for harmonic mitigation of grid-connected power converters is proposed. Based on a modeling of this novel converter configuration, an ...operating strategy is derived to accomplish this task with low control bandwith, low passive filtering effort, and high efficiency with only a small increase in installed semiconductor power.
In this brief, the minimax design problem of graph filter using Chebyshev polynomial approximation (CPA) is studied. First, conventional CPA graph filter design is investigated to show that it does ...not provide the minimax design, so the peak error of the spectral response of the designed filter is not minimized. Then, a spectral transformation is used to convert the minimax design problem of CPA graph filter into the one of the type-I linear-phase FIR digital filter such that the Parks-McClellan method can be employed to obtain the optimal filter coefficients of minimax design. Next, using the recurrence relation of Chebyshev polynomials, an implementation structure of CPA graph filter with low computational complexity is presented. Finally, a graph signal denoising application example is illustrated to show the usefulness of the proposed CPA graph filter.
The use of a filter bank of IIR filters for the spectral decomposition and analysis of signals has been popular for many years. As such, a new filter-bank resonator-based structure, representing an ...extremely hardware-efficient structure, has received a good deal of attention. Recently, multiple-resonator (MR)-based and general cascaded-resonator (CR)-based filters have been proposed. In comparison to single-resonator-based analyzers, analyzers with a higher multiplicity of resonators in the cascade provide lower side lobes and a higher attenuation in stopbands. In previous works, it was shown that the CR-based filter bank with infinite impulse response (IIR) filters, which is numerically more efficient than one with finite impulse response (FIR) filters, is suitable for dynamic harmonic analysis. This paper uses the same approach to design complex digital filter banks. In the previous case, the optimization task referred to the frequency responses of harmonic filters. In this work, the harmonic filters of the mother filter bank are reshaped so that the frequency response of the sum (or difference, depending on the parity of the number of resonators in the cascade) of two adjacent harmonic filters is optimized. This way, an online adaptive filter base can be obtained. The bandwidth of the filters in the designed filter bank can be simply changed online by adding or omitting the output signals of the corresponding harmonics of the mother filter.
This paper reports on dual-mode-cavity-resonator-based bandpass filters (BPFs) with multiple levels of transfer-function tunability. They are based on substrate-integrated-waveguide cavity resonators ...that are loaded by four identical metallic posts and give rise to two degenerate modes that are exploited for the filter design. By loading the ends of the posts with variable-reactance elements, quasi-elliptic-type filtering transfer functions with multiple levels of spectral adaptivity can be obtained. These reconfiguration properties include center-frequency control, bandwidth tuning, and intrinsic RF switching-off. The proposed adaptive BPF concept can be extended to high-order transfer functions shaped by <inline-formula> <tex-math notation="LaTeX">2N </tex-math></inline-formula> poles and <inline-formula> <tex-math notation="LaTeX">2N </tex-math></inline-formula> transmission zeros (TZs) for BPFs composed of <inline-formula> <tex-math notation="LaTeX">N </tex-math></inline-formula> dual-mode resonators. To prove the experimental viability of the engineered tunable BPF concept, a two-pole/two-TZ prototype and a four-pole/four-TZ prototype with tunable transfer functions in the 1.5-3 GHz band were built and measured.
In this letter, a new coupling structure implemented on a single-layer substrate and its application to design substrate integrated waveguide (SIW) dual-band and wide-stopband bandpass filters are ...presented. The TE 101 and the TE 102 modes of SIW cavity are used to design the proposed filters. By adjusting the dimensions of the coupling structure, the coupling coefficients of TE 101 and TE 102 modes can be controlled that can be used to design wide-stopband and dual-band bandpass filters. In the dual-band filter design, a slotline perturbation is used to lower the resonant frequency of TE 102 mode while it has little effect on TE 101 mode. To validate the proposed design approach, two SIW bandpass filters (wide-stopband and dual-band) are designed, fabricated, and measured.
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