Characteristic Impedance Ratio Research Articles

Dual polarity open circuit voltage in triboelectric nanogenerators originated from two states series impedance

Experimental and simulation studies demonstrated that the initial voltage setting significantly influences the open-circuit voltage (VOC) in triboelectric nanogenerators (TENGs). Utilizing diode configurations, we consistently observed two distinct VOCs independent of the initial settings. A lower VOC corresponded to the surface voltage (VSurface), while a higher VOC was amplified by the product of the VSurface and the TENG's characteristic impedance ratio. Notably, a lower measurement system capacitance provided a more precise representation of the inherent characteristics of the TENG. Conversely, an increase in system impedance led to a convergence of the two VOCs and a reduction in their magnitudes relative to VSurface. These findings suggest that optimizing the initial/repeated charge balancing and minimizing capacitive loads are crucial for maximizing TENG output power in practical applications.

Compact and Broadband Microstrip Band-Stop Filters with Single Rectangular Stubs

In this research, a compact and broadband microstrip line quarter-wavelength open circuited stub, which is the core of the band-stop filter, is studied from the viewpoint of the characteristic impedance ratio between the main transmission line and the stub line. Furthermore, a circuit pattern in which an inductive diaphragm is inserted at the stub attachment point using a stepped impedance structure is examined, and an evaluation of frequency adjustment and miniaturization is investigated. The results are compared with the well-known radial stub. Good agreement was obtained between the measured and simulated values up to 5 GHz. Good stop bandwidth was obtained, and the validity of the proposed method is confirmed. The application to other frequency bands is straightforward. The proposed structure is applicable as an alternative to the existing radial stub used for bias T to prevent the reverse flow of the Radio frequency (RF) signal to direct current (DC) source. It is also applicable for the waveguide E-plane band-stop filter, for preventing unwanted leakage from narrow gaps by substituting to a short-circuited stub with a capacitive window, by using the same approach used in the microstrip line H-plane discontinuity.

Design of a Suspended Stripline Narrow Bandpass Filter with Ultrawideband Harmonic Suppression

A design method of narrow bandpass filters (NBPFs) of 4–6% bandwidth with ultrawideband suppression of harmonic passbands, utilizing two cascaded step impedance resonators (SIRs) in a suspended stripline, is proposed in this paper. The proposed design utilized the characteristics of a suspended stripline, which provides a much higher characteristic impedance ratio as compared with that of the microstripline, enabling ultrawideband harmonic suppression. As an example of the NBPF, a filter with a passband center frequency f0 of 0.75 GHz and bandwidth of 5% was implemented and proved to suppress the harmonic passbands up to 13.5 f0. Since the proposed filter was implemented on the suspended stripline, the passband insertion loss was only −0.9 dB, which is low as compared with other previous designs. The proposed filter is a compact high-performance low-loss NBPF, which can be applicable to various wireless systems.

Design and study of enhanced wideband transition between coplanar waveguide and broadside coupled stripline

Enhanced wideband transition between coplanar waveguide (CPW) and broadside coupled stripline (BCS) with arbitrary characteristic impedance ratio is developed on a basis of an improved tightly coupling, via-hole-free structure. The E-field of CPW gradually changes to that of BCS within a wide bandwidth with ratio up to 10.4:1. Parametric studies of the transition are carried out and four different back-to-back prototypes are simulated, fabricated and measured. It is shown that maximum operation bandwidth from 1.16 to 12.01 GHz for return loss higher than 10 dB and average insertion loss of 1.41 dB can be obtained.

PI-SIR과 OLRR을 이용한 마이크로스트립 이중 대역 여파기의 설계 방법

In this paper, dual-band bandpass filter by using Pseudo-Interdigital Stepped-Impedance Resonator(PI-SIR) and Open-Loop Ring Resonator(OLRR) is proposed. The first passband and second passband are formed by PI-SIR and the second passband is reinforced by an OLRR. In a PI-SIR the first band and second band are easily and exactly adjusted by characteristic impedance ratio and electrical length ratio. The proposed design method may be confirmed to be useful from fabricated and measured results for dual-band bandpass filter operated at 2.45 GHz and 5.8 GHz.

DESIGN AND FABRICATION OF A COMPACT QUAD-BAND BANDPASS FILTER USING TWO DIFFERENT PARALLEL POSITIONED RESONATORS

A novel microstrip quad-band bandpass fllter was designed and fabricated on an Al2O3 ceramic substrate of 1mm thick. Two difierent types of open-loop resonator | a winding line-shaped resonator (WLR) and a stepped impedance resonator (SIR) | were positioned in parallel at the two sides of input/output microstrip lines that had the same coupling lengths and coupling gap widths. The proposed fllter was based on a WLR with four difierent resonant frequencies: 1.23GHz, 2.49GHz, 3.73GHz, and 5.41GHz. By carefully selecting the resonant frequencies of the two resonators to be slightly difierent, the phase difierence for the signals in the two resonators was negative, indicating that energy cancellation occurred, resulting in wide bandwidths and deep transmission zeros. The spurious resonant frequencies of the SIR were designed to be non-integer multiples of the fundamental resonant frequency by adjusting the length, characteristic impedance ratio, and electrical length. The SIR was designed to have three resonant frequencies at around 2.27GHz, 3.37GHz, and 4.94GHz, which had phase difierences with the WLR's resonant frequencies of 2.49GHz, 3.73GHz, and 5.41GHz. Finally, a novel quad-band fllter with a narrow band in the L2-band (GPS, 1.227GHz)

The compact 3‐stage 2.4/5.2 GHz bandpass filter with modified winding hairpin structure and insert coupling

AbstractTwo hairpin resonators, one “Z‐type” modified stepped‐impedance resonator, and two transmission lines are composed to design the compact and miniature dual‐band bandpass filters (BPFs).The designed BPFs are presented to operate at 2.4/5.2 GHz for industrial, scientific, and medical (ISM, 2.4 GHz) and WLAN applications (2.4/5.2 GHz) without additional impedance matching network. The 2.4 GHz and 5.2 GHz dual‐band can be simultaneously excited and tuned by adjusting the electric length ratio (θ) and characteristic impedance ratio (K) of resonators. Cascaded arrangement is designed for wide bandwidth and high out‐of‐band rejection, and the “Z‐type” resonator and insert coupled modification are used to increase the utility rate of space and reduce the size of designed filter. Al2O3 ceramic with thickness of 0.635 mm and dielectric constant of 9.4 used as the substrate, and the designed filters are fabricated by printing method. Because of higher dielectric constant substrate and modified structure, the proposed filters show the advantages of wide bandwidth, low insertion loss, high out‐of‐band rejection, simple circuit, and tiny size. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1156–1159, 2010; Published online in Wiley InterScience (www. interscience.wiley.com). DOI 10.1002/mop.25128

스텝 Perturbation의 영향에 따른 주기적 스텝 임피던스 링 공진기의 해석 및 이중 모드 대역 통과 필터의 적용

Dual-mode bandpass filter was designed by using periodic stepped impedance ring resonator with step perturbation. The periodic stepped impedance ring resonator has the effects of size reduction and harmonic suppression by changing characteristic impedance ratio. The perturbation for dual-mode generation was also easily controlled by characteristic impedance ratio, and the variation of dual-mode resonant frequencies and attenuation pole frequencies were analyzed by the effect of step perturbation. Chip capacitors were used for input/output coupling, and the variation of center frequency by the coupling capacitance and step perturbation was also considered. From the results, two types of 2 GHz dual-mode bandpass filter were fabricated in size of , those have different attenuation poles and bandwidths. The measured results of proposed bandpass filters showed a good agreement with the calculated estimations, and those have insertion loss of 2.52, 0.52 dB and 3 dB bandwidth of 4.03, 15.02 %, respectively.

Design Consideration for a Two-Distributed-Junction Tuning Circuit

We describe a novel method of designing a tuning circuit with two half-wave distributed junctions separated by a half-wavelength microstripline, which analytically determines the circuit parameters such as the minimum current density of the junctions and the characteristic impedances of the distributed junctions and the microstripline. The tuning circuit was approximated by simple transmission theory and then simplified with ideal circuit components for analysis. We applied Chebyshev’s band-pass filter theory, in part, to optimize the circuit design. The analytical results revealed that a high characteristic-impedance ratio between the distributed junctions and the microstripline is necessary to obtain broadband matching using low-current-density junctions. The experimental results for all-NbN SIS mixers we designed with this method demonstrated double-sideband (DSB) receiver-noise temperatures of 6–10 quanta from 710 to 810 GHz for a mixer with a current density of only 4 kA/cm2 (estimated ωCJRN product of 37 at 750 GHz). The RF bandwidth was broader than that of a conventional full-wave distributed SIS mixer with the same current density.

Non-equilibrium split Hopkinson pressure bar procedure for non-parametric identification of complex modulus

A split Hopkinson pressure bar procedure was developed for non-parametric identification of complex modulus under conditions of non-equilibrium and axially non-uniform stress. Two simplified procedures were also established. The first requires low frequency and/or short specimen. The second, identical to a classical procedure based on equilibrium, requires that also the specimen-to-bar characteristic impedance ratio be low. Both overestimate the magnitude of the complex modulus, the second even at low frequencies. Tests were carried out with polymethyl methacrylate and aluminium bars and with polypropylene specimens having diameter 20 mm and lengths 10, 20, 50 and 100 mm. The complex moduli identified are in good to fair agreement with published results up to 10 kHz for all specimens with polymethyl methacrylate bars and for the 10–50 mm specimens with aluminium bars. The quality of the results is sensitive to truncation and to imperfect contact at the bar-specimen interfaces.

Efficiency of percussive drilling with extension rods

Extension drilling of rock is simulated numerically using a Victor desk-top computer. The hammer, adapter and extension rods are uniform and have the same characteristics impedances. The same is true for the joints and the bit. Two efficiencies are determined as functions of six dimensionless parameters which represent the number of joints, the joint-to-hammer length ratio, the joint-to-rod characteristic impedance ratio, the initial gap between bit and rock and the bit/rock interaction (two parameters). The first efficiency is defined as the ratio of the work performed on the rock to the impact kinetic energy of the hammer. The second is based on the sum of the work performed on the rock and the rebound kinetic energy of the hammer, which is assumed to be fully retrieved. Both efficiencies generally decrease with the number of joints and the joint-to-hammer length ratio. Exceptionally, however, the efficiencies may increase slightly with the number of joints. The difference between the second and first efficiency, which is due to hammer rebound, generally increases when the rock becomes increasingly hard. This dependence on rock hardness is strongest when the number of joints and the joint-to-hammer length ratio are low. In the absence of joints the efficiencies have an oscillatory dependence on a small initial gap. When one or several joints are used, however, the efficiencies essentially decrease with the initial gap.

Three unusual strokes in a triggered lightning flash

Time‐resolved photographic records of three strokes of a triggered lightning flash are examined. These strokes exhibit several examples of novel behavior that include (1) the abrupt transformation of dart leaders to stepped leaders and (2) the partial “reflection” of dart leader luminosity back up the channel. Both phenomena are associated with an apparent discontinuity in channel characteristics between the natural and artificial (wire) sections of the channel. We estimate the ratio of characteristic impedances for these sections to have an upper bound of about a factor of 3. Analysis of one of the dart leader“reflections” yields a propagation speed of 9.6×107 m/s, whereas the dart leader and return stroke speeds (two‐dimensional) over the same channel section are 1.7×107 m/s and 13×107 m/s respectively. Also, one of the return strokes reveals the occurrence of two distinct waves of luminosity that are separated by only 5 μs and that travel up nearly identical channels that differ only in the channel terminus.

Inversion of the geophysical inverse problem for n layers with nonuniqueness reduced to n cases

A new method is described for reducing nonuniqueness in the geophysical inverse problem for n layers to n cases, provided the ratio of characteristic impedances of sequential layers is of the order of unity and upper and lower layer boundary conditions are known. The method is based on impedance concepts which allow application to a number of different electromagnetic or acoustic experimental methods. Using transformations, the method reduces the nonlinear problem to a linear one as an eigenvalue formulation without approximation. This preserves the nonlinear nature of the problem and increases the significance of the results. Experimental results are given for several electromagnetic applications where the complex permittivity ε = ε′ − iε″ is determined for shallow (35 m) stratified geosections. The frequency range is dictated by multiples of the electrical or acoustic “quarter‐wave” thickness of the layers and, in the particular electromagnetic (EM) studies made, it has been 1 to 8 MHz. Application to ocean bottom sub‐layering is also proposed, arising from the feasibility of experiments under a conductive lake to which mathematical equivalence is shown.

Attenuation of sound in lined ducts

Measurements made in a lined standing wave tube of variable rectangular cross-section are compared with an approximate solution of Scott's equation. A method of measurement of the characteristic impedance ratio and complex propagation constant in the bulk of the lining material is described. These quantities are required for substitution into Scott's equation.

SUR LA REPONSE TRANSITOIRE DES FORMATIONS RESISTIVES*

ABSTRACTThis paper deals with transient response of resistive formations to pulse sources. Computation of solutions of equations such as: image is linked to computation of solutions of equations such as: image It can be used in the case where several media exist, the conductivities of which are σ1 σ2.The method consists in establishing a correspondence between the case to be dealt with and a fictitious region of space with the same interfaces, in which the propagation of a disturbance obeys Equation (2).Velocities C1 C2. are related to conductivities by the condition image At the interfaces, the distribution of incident energy between transmitted and reflected energy is related to the ratio of characteristic impedances, i.e. image in the real case (ω is the angular frequency) and C1/C2 in the fictitious case.These ratios are the same because of Equation (3).Time variation g(θ) of solution of (1) in a given point is computed from time variation of solution of (2) at the same point by means of the transformation image (in which τ is the actual time and T the time unit).Equation (4) originates from a formula of symbolic calculus, that allows the Laplace transform of F(Vp) to be calculated from the known Laplace transform of F(p). This correspondence is the one that allows passage from in (1) to in (2)Equation (4) becomes considerably simpler when the response to the unit impulse consists (as happens most often) of the sum of a finite or infinite number of pulses The results is then a sum of functions such as: image Hence, this procedure appears as an extension to systems that obey Equation (1) of the image theory very often used when Equation (2) is applied.