High frequencies attenuation

Sometimes the high-frequency attenuation is insufficient to meet the specifications and a third pole needs to be added to the EMI filter. This filter is typically a differential-mode filter and will share the Y capacitors from the common-mode filter. Its corner frequency is typically the same as the commonmode filter. This filter is made up of a separate choke on each power line, and is placed between the input rectifiers and the common-mode filter. 

In Chapter 7, the high-frequency attenuation characteristics of polynomial filters are discusssed. These considerations are relevant to questions regarding the desirability of a single application of a filter of given length as opposed to multiple application of shorter filters. 

Use inductive output coupling from the resonant plate circuit and possibly a capacitive or Paraday shield between the coupling coil and the tank coil, or a high-frequency attenuating circuit such as a jr or jr-L network. 

A corresponding composite probe with the same frequency and crystal size, however, detects the test flaw much better the echo has a 12 dB higher amplitude (see Fig. 4) and in addition, the noise level is much lower, resulting in an improved signal to noise ratio. This effect is especially observed at high sound attenuation. However, in materials with low attenuation or in case of shorter sound paths the standard probe yields a comparable good signal to noise ratio. 

Waveguides are coimnonly used to transmit microwaves from the source to the resonator and subsequently to the receiver. For not-too-high-frequency radiation (<10 GHz) low-loss MW transmission can also be achieved usmg strip-lines and coaxial cables. At the output of a klystron an isolator is often used to prevent back-reflected microwaves to perturb the on-resonant klystron mode. An isolator is a microwave-ferrite device that pemiits the transmission of microwaves in one direction and strongly attenuates their propagation in the other direction. The prmciple of this device involves the Faraday effect, that is, the rotation of the polarization... 

The attenuation of ultrasound (acoustic spectroscopy) or high frequency electrical current (dielectric spectroscopy) as it passes through a suspension is different for weU-dispersed individual particles than for floes of those particles because the floes adsorb energy by breakup and reformation as pressure or electrical waves josde them. The degree of attenuation varies with frequency in a manner related to floe breakup and reformation rate constants, which depend on the strength of the interparticle attraction, size, and density (inertia) of the particles, and viscosity of the Hquid. 

Ultrasonic Properties. Vitreous sihca of high purity, such as the synthetic type, has an unusually low attenuation of high frequency ultrasonic waves. The loss, is a linear function of frequency, up to the 30—40 MHz region and can be expressed a.s A = Bf, where B = 0.26 dB-MHz/m for shear waves and 0.16 dB-MHz/m for compressional waves (168). 

The addition of this stage of filtering will bring the very high-frequeney attenuation under eontrol and further attenuate any differential-mode noise on the earth ground lead. It will also produee a eombined attenuation of -36 dB at the switehing frequency of the power supply. 

Reciprocating compressors These cause very high noise levels at low frequency (typically, below 420 Hz). The low-frequency noises are very difficult to attenuate, and the most popular solution is to use rotary (vane type) compressors. These are inherently quieter and have the further advantage that the noise they generate is at high frequency (typically, above 1 kHz) and is therefore easy to attenuate. 

With nondestructive ultrasonic test back and forth scanning of a specimen is accomplished with ultrasonics. This NDT can be used to find voids, delaminations, defects in fiber distribution, etc. In ultrasonic testing the sound waves from a high frequency ultrasonic transducer are beamed into a material. Discontinuities in the material interrupt the sound beam and reflect the energy back to the transducer, providing data that can be used to detect and characterize flaws. It can locate internal flaws or structural discontinuities by the use of high frequency reflection or attenuation (ultrasonic beam). 

High-frequency excitatory stimuli which were introduced to the first element was amplified and transmitted to the ninth element. Low-frequency excitatory stimuli which was introduced to the fifth element was attenuated during propagation leading to selective elimination of synaptic coimection between the seventh and fourth elements. 

Is this necessary No. The HV high frequency spikes generated by a car coil are already filtered out by the car s on-board electronic equipment, thus any additional attenuation is unnecessary. 

We see that the amplitude-transfer characteristic is given by 27r[l + (coRC)2] -1/2. The power-transfer characteristic is given by the square of this quantity. It has the form of a Cauchy function and attenuates high frequencies. Brodersen (1953) and Stewart (1967) have analyzed in detail the performance of other linear electrical filters applied in spectroscopy. 

Because the most serious problem arising in the deconvolution of spectra is that of noise, detailed attention to smoothing in a fashion consistent with the uniform attenuation of high-frequency noise will result in the best possible deconvolution results. 

The inversion procedure is most straightforward when attenuation in the coupling fluid is ignored. This may present problems in high-frequency applications. 

Dransfeld, K. and Salzmann, E. (1970). Excitation, detection and attenuation of high-frequency elastic surface waves. In Physical acoustics VII (ed. W. P. Mason and R. N. Thurston), pp. 260-83. Academic Press, New York. [117]... 

For a detector to be of use in quantitative analysis, the signal output should be linear with concentration for a concentration-sensitive detector and with mass for a mass-sensitive detector. Some detectors have an additional time constant purposely introduced to remove the high-frequency noise. This should always taken into consideration, since a slow detector response can significantly broaden and attenuate chromatographic peaks relative to those actually sensed. Moreover, a versatile detector should have a wide linear dynamic range so that major and trace components can be determined in a single analysis, over a wide concenua-tion range. 

Comparison of intensities of homoisotopic and heteroisotopic pairs shows that coupling enhances the high frequency bands at the expense of the low frequency ones. In both A13(12,13) and A13(13,12), the relative intensities of Ai and A3 are very similar, but in A13(12,12) and A13(13,13), the high frequency band is enhanced, while the low frequency one is attenuated, as in the example shown in Figure 27. The sense of the intensity pattern shows that the C02s are closer to side-by-side than end-to-end, and further analysis will show that the long axes of Aj and A3 differ in direction by 29.5°. 

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