Millimeter wavelengths, frequency-dependence

We remeasured, therefore, the cell-paste absorption by using, in this case, a quasi-optical spectrometer (23). In order to avoid wavelength-dependent diffraction of the sample, the millimeter-wave frequency was veried between 40 and 60 GHz, and the average of the apparent transmission was measured. This averag-... 

We see from Fig. 26a (solid line 1) that the loss spectrum, calculated for our model with the same parameters, as chosen above (Table IX), exhibits resonance lines at the frequencies v < 50 cm-1. At v < 20 cm-1 the calculated solid loss curve 1, becoming nonresonant, coincides with the nonresonant dashed curve 2 calculated from Eqs. (72)-(74) with cfit = 2.35. Both loss s" curves 1 and 2 decrease linearly with v (in the log-log plot) in the interval from 50 to 0.1 cm-1 For further decrease of frequency the empirical dependence (72) exhibits a minimum at v about 0.1 cm-1 (viz, in the millimeter wavelength region). Near this minimum and at lower frequencies, our molecular model should not be applied. 

The frequencies generated by the proposed method depend on the wavelength and hand movements. However, usual hand movement on the surface of several millimeter wavelengths generates the suitable frequency range for FA 1 consequently. 

The resolution of the ultrasonic microscope is determined by the aperture and sound wavelength. The sound wavelength, in turn, is determined by the ultrasonic frequency. Using water as the coupling medium, the maximiun resolution is 0.4 pm at 2 GHz, 15 pm at 100 MHz, and 500 pm at 10 MHz. The penetration depth depends on the frequency, the type of material, and the surface quality of the specimen. The scattering of the sound on the specimen surface is influenced by its roughness. The penetration depth can reach several millimeters at low sound frequencies. 

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