Frequency Characterization of Ferrite Beads in the Microwave Range for Nonlinear Applications

2014 ◽  
Vol 802 ◽  
pp. 552-557
Author(s):  
Lauro Paulo Silva Neto ◽  
J.O. Rossi ◽  
P.A.G. Dias ◽  
J.J. Barroso
Keyword(s):  
Transmission Lines ◽  
Electromagnetic Interference ◽  
Nonlinear Behavior ◽  
Complex Permeability ◽  
Microwave Range ◽  
Limited Information ◽  
Low Frequencies ◽  
High Power Microwave ◽  
Low Pass ◽  
Low Pass Filters

Ferrite beads are ferromagnetic materials that exhibit a small inductance at low frequencies, becoming resistive at high frequencies. These devices are used as low pass filters for reducing electromagnetic interference (EMI) in communications and power electronics because the resistive losses attenuate the undesired frequencies. As ferrite beads have a nonlinear behavior with current and frequency they have been used in nonlinear transmission lines (NLTLs) for high power microwave generation in space and defense applications. In this work, high frequency ferrite beads are characterized in the frequency range up to 1 GHz by measuring S11 reflection parameter in order to calculate their complex permeability and losses, key parameters in the design of NLTLs. In addition, X-ray diffraction (XRD) is used to identify their chemical element composition. Finally, the motivation for this work is basically due to the limited information on ferrite materials provided by the manufacturers.

Performance of Valveless Diffuser Micropumps Under Harmonic Piezoelectric Actuation

2006 ◽  
Author(s):  
M. T. Ahmadian ◽  
M. H. Saidi ◽  
Amin Mehrabian ◽  
M. Bazargan ◽  
S. D. Kenarsari
Keyword(s):  
Flow Rate ◽  
Flow Direction ◽  
Actuation Frequency ◽  
Low Frequencies ◽  
High Frequencies ◽  
Flow Response ◽  
Parabolic Velocity Profile ◽  
Electrical Analogy ◽  
Low Pass ◽  
Low Pass Filters

Valveless piezoelectric micropumps are in wide practical use due to their ability to conduct particles with absence of interior moving mechanical parts. The objective of this paper is to obtain the fluid flow response to actuation frequency of a passive diffuser valve under harmonic pressures. In this regards a 2D model of a micropump valves and chambers is analyzed. The analysis is performed for 10Kpa back pressure on micropump chamber and actuation frequencies within the range of 1Hz to 10 KHz. Results show the highest velocity in the direction of diffuser axis occurs at the narrow diffuser neck while flow direction reverses every half period. For low frequencies, a parabolic velocity profile is observed at the valve midway while, instabilities with the tendency of transition to boundary layer dominant profile is observed for high actuation frequencies. Oscillating flow in diffuser indicates existence of high shear stress regions near the wall along with the flow reversal in the center at high frequencies. Both valve and pump net flow rate decrease drastically as the frequency approaches a certain value. From electrical analogy viewpoint, nozzle/diffuser passive valves can be modeled as Low Pass Filters (LPF). The results are in good agreement with the relevant analytical findings. Similar to analytical results, flow rate is approximately in phase with actuation at low frequencies but phase shift ascends as actuation frequency is increased. The main head loss of flow occurs at the diffuser valves while sudden contraction and expansion of streamlines at the diffuser entrance and exit involve only 22% of the total energy. The results are in agreement with the previous experiments of micropump flow at high frequencies.

Effect of Actuation Frequency on the Performane of Diffuser Micropumps

2006 ◽  
Author(s):  
Amin Mehrabian ◽  
M. T. Ahmadian
Keyword(s):  
Flow Rate ◽  
Flow Direction ◽  
Actuation Frequency ◽  
Low Frequencies ◽  
Flow Response ◽  
Parabolic Velocity Profile ◽  
Electrical Analogy ◽  
Low Pass ◽  
Low Pass Filters ◽  
Contraction And Expansion

Valveless piezoelectric micropumps are in wide practical use due to their ability to conduct particles with absence of interior moving mechanical parts. The objective of this paper is to obtain the fluid flow response to actuation frequency of a passive diffuser valve under harmonic pressures. In this regards a 2D model of a micropump valves and chambers is analyzed. The analysis is performed for 10Kpa back pressure on micropump chamber and actuation frequencies within the range of 1 Hz to 10 KHz. Results show the highest velocity in the direction of diffuser axis occurs at the narrow diffuser neck while flow direction reverses every half period. For low frequencies, a parabolic velocity profile is observed at the valve midway while, instabilities with the tendency of transition to boundary layer dominant profile is observed for high actuation frequencies. Oscillating flow in diffuser indicates existence of high shear stress regions near the wall along with the flow reversal in the center at high frequencies. Both valve and pump net flow rate decrease drastically as the frequency approaches a certain value. From electrical analogy viewpoint, nozzle/diffuser passive valves can be modeled as Low Pass Filters (LPF). The results are in good agreement with the relevant analytical findings. Similar to analytical results, flow rate is approximately in phase with actuation at low frequencies but phase shift ascends as actuation frequency is increased. The main head loss of flow occurs at the diffuser valves while sudden contraction and expansion of streamlines at the diffuser entrance and exit involve only 22% of the total energy.

Using Microstrip LPF in Gysel Power Divider for Extreme Size Reduction and Higher Order Harmonic Suppression

Frequenz ◽  
2015 ◽  
Vol 69 (7-8) ◽  
Author(s):  
H. Siahkamari ◽  
S. Vahab A. Makki ◽  
S.-A. Malakooti
Keyword(s):  
Transmission Lines ◽  
Return Loss ◽  
Higher Order ◽  
Power Divider ◽  
Harmonic Suppression ◽  
Harmonic Rejection ◽  
Measurement Results ◽  
Low Pass ◽  
Power Handling Capability ◽  
Low Pass Filters

AbstractThis paper presents a new design of a compact Gysel power divider with harmonic suppression. It comprises six similar low-pass filters in lieu of six conventional transmission lines in the Gysel power divider. Not only does the proposed power divider extremely reduce the occupied area to 22.7% of the conventional Gysel power divider at 900 MHz, but also it features the higher order harmonic rejection. Simulation and measurement results show good insertion loss, return loss, isolation, and wide stopband bandwidth, while maintaining high-power handling capability over the Wilkinson power divider.

scholarly journals Frequency domain analysis of core inflation measures for Brazil

2005 ◽  
Vol 35 (1) ◽  
pp. 5-36
Author(s):  
Eurilton Araújo ◽  
Antonio Fiorencio
Keyword(s):  
Frequency Domain ◽  
Frequency Domain Analysis ◽  
Frequency Noise ◽  
Low Frequencies ◽  
Trimmed Mean ◽  
Core Inflation ◽  
Trend Inflation ◽  
Low Pass ◽  
Low Pass Filters ◽  
Frequency Domain Properties

This paper analyses the frequency domain properties of two well-known measures of core inflation: the trimmed mean estimator and the SVAR estimator. It also investigates whether a small modification of the trimmed mean estimator enhances its capacity of filtering high‑frequency noise. We find that the two versions of the trimmed estimator are rather similar. They work as imperfect approximations for low pass filters. Therefore, they are capturing very well trend inflation. The SVAR estimator, however, is quite different from both of them. It emphasizes intermediate frequencies rather than low frequencies, indicating that cyclical movements associated with excess demand pressures are very important in the medium run.

High-Performance On-Chip Low-Pass Filters Using CPW and Slow-Wave-CPW Transmission Lines on Porous Silicon

2016 ◽  
Vol 63 (1) ◽  
pp. 439-445 ◽  
Author(s):  
Panagiotis Sarafis ◽  
Androula G. Nassiopoulou ◽  
Hamza Issa ◽  
Philippe Ferrari
Keyword(s):  
Porous Silicon ◽  
Slow Wave ◽  
Transmission Lines ◽  
High Performance ◽  
Low Pass ◽  
On Chip ◽  
Low Pass Filters

The S-SH Confusion Test and the Effects of Frequency Lowering

2019 ◽  
Vol 62 (5) ◽  
pp. 1486-1505
Author(s):  
Joshua M. Alexander
Keyword(s):  
Cognitive Processing ◽  
Hearing Aids ◽  
Response Times ◽  
Nonlinear Frequency ◽  
Low Frequencies ◽  
Frequency Compression ◽  
Negative Side ◽  
Minimal Word ◽  
Low Pass ◽  
Negative Side Effects

PurposeFrequency lowering in hearing aids can cause listeners to perceive [s] as [ʃ]. The S-SH Confusion Test, which consists of 66 minimal word pairs spoken by 6 female talkers, was designed to help clinicians and researchers document these negative side effects. This study's purpose was to use this new test to evaluate the hypothesis that these confusions will increase to the extent that low frequencies are altered.MethodTwenty-one listeners with normal hearing were each tested on 7 conditions. Three were control conditions that were low-pass filtered at 3.3, 5.0, and 9.1 kHz. Four conditions were processed with nonlinear frequency compression (NFC): 2 had a 3.3-kHz maximum audible output frequency (MAOF), with a start frequency (SF) of 1.6 or 2.2 kHz; 2 had a 5.0-kHz MAOF, with an SF of 1.6 or 4.0 kHz. Listeners' responses were analyzed using concepts from signal detection theory. Response times were also collected as a measure of cognitive processing.ResultsOverall, [s] for [ʃ] confusions were minimal. As predicted, [ʃ] for [s] confusions increased for NFC conditions with a lower versus higher MAOF and with a lower versus higher SF. Response times for trials with correct [s] responses were shortest for the 9.1-kHz control and increased for the 5.0- and 3.3-kHz controls. NFC response times were also significantly longer as MAOF and SF decreased. The NFC condition with the highest MAOF and SF had statistically shorter response times than its control condition, indicating that, under some circumstances, NFC may ease cognitive processing.ConclusionsLarge differences in the S-SH Confusion Test across frequency-lowering conditions show that it can be used to document a major negative side effect associated with frequency lowering. Smaller but significant differences in response times for correct [s] trials indicate that NFC can help or hinder cognitive processing, depending on its settings.

Ku/Ka-band Compact Orthomode Junction with Low Pass Filters for High Power Applications

2015 ◽  
Vol E98.C (2) ◽  
pp. 156-161
Author(s):  
Hidenori YUKAWA ◽  
Koji YOSHIDA ◽  
Tomohiro MIZUNO ◽  
Tetsu OWADA ◽  
Moriyasu MIYAZAKI
Keyword(s):  
High Power ◽  
Ka Band ◽  
Low Pass ◽  
Low Pass Filters
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