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A frequency band in which the attenuation of a filter is essentially zero.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



the frequency range within which the amplitude-frequency characteristic of an acoustic, radio-engineering, or optical device is sufficiently uniform to assure the transmission of a signal without substantial distortion of the signal’s shape.

The basic parameters of a passband are the width of the band and the nonuniformity of the amplitude-frequency characteristic within the band. The bandwidth is usually defined as the difference between the upper and the lower limiting frequencies of the section of the amplitude-frequency curve where the minimum amplitude of the oscillations is not less than 0.707, or Passband, of the maximum amplitude. The nonuniformity of the amplitude-frequency curve quantitatively characterizes the degree to which the curve deviates from a straight line parallel to the frequency axis. The bandwidth is expressed in frequency units, such as hertz (Hz), and nonuniformity is expressed in relative units or in decibels.

The passband required for a particular device depends on the device’s purpose. For example, telephone systems require band-widths of 300 to 3400 Hz, high-quality reproduction of musical performances requires 30 to 16,000 Hz, and television broadcasting uses bandwidths of up to 8 MHz. The widening of a passband permits the transmission of a greater amount of information; by reducing the nonuniformity of the amplitude-frequency characteristic within the passband, the reproduction of the shape of the transmitted signal can be improved. Passbands are sometimes defined also in terms of the device’s phase-frequency characteristic.


Gonorovskii, I. S. Radiotekhnicheskie tsepi i signaly. 2nd ed. Moscow, 1971.

A. S. Grinchik

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Greater resolution of transmission baud rate with a wide range provides the benefit of optimising spectral passband utilisation of an optical channel, while enabling the use of lower modulation order operation to improve channel performance.
This particular geometry could help to create a pair of transmissions zeros on both sides of the passband. As seen from Figure 2, the odd mode resonant frequency is located at the lower passband, and the even mode resonant frequency is at the higher passband.
In addition to a narrow passband around the center frequency, these NBPFs typically have a property of having undesired multiple harmonic passbands at odd-harmonic frequencies of the passband center frequency.
It eliminates the need for a centre frequency and the fixed passband width as it is used in [33].
Set the iteration gain in the passband K = 1, the iteration gain in the stopband K = 10, the maximum iteration times [T.sub.0] = 100, and the predefined permitted error [lambda] = 1 x [10.sup.-5].
[[omega].sub.k]} is a set of uniformly distributed dense grid over the , passband and the stopband.
However, the stopband bandwidth of photonic bandgap (PBG) and DGS are enhanced by using periodic structures, corresponding to sizes and transmission losses in passband. Moreover, the high attenuation rates are also obtained with cells in series .As reported in, wideband performance of filters was generated by using three cells in series.
where subscript 1 represents the first passband and 2 is the second passband.
Selectivity is another critical issue for BPFs and can be improved by introducing TZs near the passband. Usually, nonadjacent coupling, including cross coupling and S-L coupling, can generate TZs by providing a multipath effect [9].
On the other hand, traditional synthesis design was systematically developed under the assumption of narrow passband. Therefore, the ultra-wide bandwidth specified by Federal Communications Commission (FCC) in 2002 creates a tremendous challenge in designing UWB BPF [2-15].