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81 A  DF  .~> Coaxial or microstrip
81 B  DF  .~> Waveguide type

Unofficial Alpha Subclasses: R A B


Classification: 333/81

(under the class definition) Devices and networks consisting of one or more elements which exhibit only a positive resistance effect and which reduce the intensity of the energy passing through the device by dissipation, (1) the elements being proportioned to permit a change in their value to control the energy loss while maintaining substantially constant input and/or output impedance of the device, and/or (2) the elements being proportioned to permit the device to be inserted in the circuit to provide an energy loss without introducing any reflections in the circuit, and/or (3) the elements being combined with a long line or long line element, and/or (4) the device or network having an impedance equal to the impedance of a specified long line and/or (5) the device or network is claimed as being particularly modified for use over a frequency band so that its characteristics are particularly related to frequency, and (6) systems within the class definition including such devices or networks.

(1) Note. The networks and devices of part 5 of the definitions may include means such as capacitors to compensate for deviations in attenuation caused by changes in frequency of the applied energy, so that the device or network acts as a pure resistance. The network or device may be modified to obtain uniform attenuation over a band of frequencies.

(2) Note. Included are T, H, pad, and ladder or lattice type networks as well as transmission line sections.

(3) Note. This subclass embraces devices wherein one or more of the elements include reactance to compensate for any inherent reactance of the element or elements, see (1) Note.

(4) Note. If the device or network does not maintain a constant input and/or output impedance, or if it would introduce reflections into the transmission line, it is excluded from this class and will be found in Class 323 Electricity: Power Supply or Regulation Systems.

SEE OR SEARCH THIS CLASS, SUBCLASS: 13, for resonator type breakdown discharge systems, which include attenuation networks.

14, for amplitude compression and expansion systems which include attenuation networks.

15, and 16, for pilot controlled systems which include attenuation networks.

17+, for automatically controlled systems which may include attenuation networks.

22, for transmission line terminations which dissipate the

applied energy.

24+, for adjustable reactive type coupling networks in general, see especially subclass 28 for equalizer networks.


181, Acoustics, appropriate subclasses, for devices for attenuating sound, see

206, for mufflers.

323, Electricity: Power Supply or Regulation Systems, see (4) Note above.

330, Amplifiers, appropriate subclasses under 157+, 185+ and 192+ for amplifiers having significant coupling which may include attenuators. 338, Electrical Resistors, appropriate subclasses, for electrical resistors, per se; and

68+, for mechanically variable resistors including potentiometers and rheostats.