Equivalent Circuit Capacitance Research Articles

Characterization of an X-Band Metamaterial Slow Wave Structure for HPM Applications

In this article, we have characterized an X-band complementary electric split-ring resonator (CeSRR) based metamaterial (MTM) slow-wave structure (SWS), suitable for high-efficiency vacuum electron devices (VEDs). The MTM SWS consists of an array of CeSRR and a circular waveguide that propagates below the cut-off frequency of an empty waveguide in the TM <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{01}$</tex-math> </inline-formula> mode. The surface current distribution has been used to predict the resonance frequency of the CeSRR. An equivalent circuit approach has been used here to obtain its equivalent circuit capacitance and inductance per unit length, which is used further to analyze the dispersion characteristics and interaction impedance of the MTM SWS. The electromagnetic (EM)simulation result showed that the dispersion bandwidth ranges from 9.53 to 9.78 GHz, and the average interaction impedance is greater than 550 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $</tex-math> </inline-formula> . Furthermore, we have designed, EM simulated, and experimentally characterized the proposed X-band MTM SWS. The experimental transmission coefficient ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{21})$</tex-math> </inline-formula> has been found approximately consistent with the EM simulated values.

Self-Calibration Method of Noncontact AC Voltage Measurement

Realizing stable and reliable monitoring of a distribution network voltage environment can obtain real-time power parameter information and ensure the normal and safe operation of transmission lines, which is of great research significance and engineering value. Based on the distributed capacitance relationship between sensor and transmission line, an equivalent circuit capacitance voltage dividing model is proposed, and the relevant factors affecting the stability of the voltage dividing ratio are analyzed. The self-calibration principle of noncontact AC voltage measurement is proposed based on the system identification theory. The noncontact sensing structure is designed, a sensor probe prototype is fabricated, and a back-end conditioning circuit is designed to realize the overall measurement system. Finally, the validity of the measurement model is verified by simulation and experiment, and a measurement platform is built which proves the feasibility of the self-calibration method for noncontact voltage measurement. The experimental results show that the error is less than ±2%. This method can correctly restore the measured voltage waveform, has good linearity, and can realize wireless data transmission, which provides a new idea for the voltage measurement method of a distribution network.

High-Performance Isolated Gate-Driver Power Supply With Integrated Planar Transformer

Wide-bandgap and silicon power semiconductor devices require advanced pulsewidth gate-driver capability to successfully convert power for high-performance operation. In this article, a simplified forward isolated resonant converter structure with an integrated planar transformer is proposed, a cost-effective solution which eliminates the need of an output filter inductor while rearranging the clamp circuit for reduced component ratings and voltage stress. The first design option uses a simple back-to-back Zener diode voltage clamp circuit for low-power dc–dc isolated power supply applications. The second design employs a lossless voltage-clamped converter with auxiliary energy-recovering winding with an application example for an isolated gate-driver power supply. Through analysis of the converter, the switching frequency has been selected in relationship to the transformer inductance and the equivalent circuit capacitance for the benefit of soft-switching power device transitions. The proposed resonant converter structure features an integrated planar transformer designed with a specific layer disposition to ensure low interwinding capacitance. The converter offers isolated supplies for a gate-driver power devices pair, such as half-bridge SiC devices. The simulation and experimental results are obtained from a gate-driver application platform to demonstrate the validity of the proposed isolated dc–dc converter design and integrated planar transformer with a total conversion efficiency of 87.7%.

Analysis for unloaded quality factor of a rectangular double-reentrant cavity with circular cylindrical ferrule for klystron using Wheeler’s incremental inductance rule

ABSTRACTClosed-form formulation for the estimation of equivalent circuit capacitance and inductance of a rectangular double-reentrant klystron cavity with circular cylindrical ferrules was developed and used for arriving at the resonant frequency of the cavity. The closed-form expression for the cavity inductance and resonant frequency were subsequently used for estimating unloaded quality factor of the cavity using Wheeler’s incremental inductance rule. The proposed analysis was validated against 3D electromagnetic analysis and measurements for a typical rectangular klystron cavity operating in C-X-bands.

Optomechanical Platform with a Three-dimensional Waveguide Cavity

At low temperatures, microwave cavities are often preferred for the readout and control of a variety of systems. In this paper, we present design and measurements on an optomechanical device based on a 3-dimensional rectangular waveguide cavity. We show that by suitably modifying the electromagnetic field corresponding to the fundamental mode of the cavity, the equivalent circuit capacitance can be reduced to 29 fF. By coupling a mechanical resonator to the modified electromagnetic mode of the cavity, we achieved a capacitance participation ratio of 43 $\%$. We demonstrate an optomechanical cooperativity, $C$$\sim$40, characterized by performing measurements in the optomechanically-induced absorption (OMIA) limit. In addition, due to a low-impedance environment between the two-halves of the cavity, our design has the flexibility of incorporating a DC bias across the mechanical resonator, often a desired feature in tunable optomechanical devices.

Dielectric relaxation and microwave dielectric properties of low temperature sintering LiMnPO4 ceramics

LiMnPO4 with olivine structure is usually widely studied as a promising cathode material for lithium batteries. In present work, LiMnPO4 ceramic has been found to have potential application on low-temperature co-fired ceramic technology. Single phase of LiMnPO4 was synthesized by one-step solid state reaction using ammonium polyphosphate (APP) as PO4 precursor. Compatibility test shows the coexistence of LiMnPO4 and silver at 750 °C. Dense LiMnPO4 ceramic with more than 95% theory density can be obtained at 750 °C. The dielectric measurement shows the dielectric relaxation which obeys the universal law with fractional exponent. The dielectric spectra are well fitted with the equivalent circuit capacitance parallel with constant phase degree. The optimized microwave dielectric properties show low dielectric constant (8.1), and high quality factor (44,224 GHz).

SWITCHABLE SQUARE LOOP FREQUENCY SELECTIVE SURFACE

A switchable square loop frequency selective surface (FSS) design is presented. The FSS is switched between reflective and transparent state by using one gap for each unit cell. Measured and simulated results are compared. PIN diodes are integrated to the FSS for electrical switching. The PIN diodes equivalent circuit capacitance element is varied to investigate its effect on the switchable FSS performance. The switchable FSS power percentages of the reflected and transmitted states are presented in tables and discussed.

Analysis of Electrical Characteristics using a Lambert W-Function Technique and MATLAB Simulation for Dye Sensitised ZnO Solar Cell

Present article deals with analysis of output characteristics in ZnO based Dye Sensitised Solar Cell (DSSC) us- ing a Lambert W-function technique and MATLAB Simulation. We have used an analytical approach having no approxi- mation for extracting various parameters of DSSC, a well known Lambert W-function technique. The model used in pre- sent work is single diode model including the capacitance in equivalent circuit and hence study its effect on current- voltage characteristics and other DSSC parameters. Results hence obtained are discussed and validated using MATLAB Simulation.

Strip gratings at a dielectric interface and application of Babinet’s principle

In this paper, we consider the transmission-line model used to calculate the transmittance of thin metallic strip gratings (at wavelengths longer than the grating period) to resolve a conflict of published expressions for the effect of a thick dielectric substrate on the equivalent circuit capacitance of capacitive gratings. By using rigorous diffraction theory we establish the correct expression and derive a modified form of Babinet’s principle for use with strip gratings on dielectric boundaries. It is found that the equivalent circuit capacitance of a strip grating on the boundary between media of refractive indices n1 and n2 is larger than its free-space value by a factor (n12+n22)/2. The result is applicable in general to the capacitive part of the equivalent circuit of grid reflectors, which are widely used at submillimeter wavelengths. A useful set of rigorously calculated transmission curves for strip gratings is presented, and these are used to establish the range of validity of the transmission-line model.