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Unidirectional means “only in one direction” (cf. Latin unus = “one”). The term is used, among other things, in communication technology, as unidirectional (data) communication . This means that communication between two participants does not take place bidirectionally (in both directions), but that a communication participant only sends data in one direction to one or more other recipients. This also means that there is no return channel available via which the recipient could inform the sending subscriber whether the message was received correctly, in order to otherwise be able to initiate the repetition of a failed transmission, for example.

Alternatively and equally, the term monodirectional (Mono = 1, means “only in one direction”) is used.

The term can also be related to telecommunications as well as entertainment media. Both radio and television in their traditional form are prime examples of one-way communication .


In the case of electronic semiconductor components , “unidirectional” means that the current (normally) may only flow through them in one direction. Such components have a polarity , i.e. a positive pole ( anode ) and a negative pole ( cathode ). This applies e.g. B. on polarized overvoltage protection diodes, so-called polarized avalanche diodes or polarized suppressor diodes and all Zener diodes . Polarized protective diodes are therefore also marked with a ring on the side of the cathode, while non-polarized protective diodes have no ring marking. Since “uni” is often incorrectly equated with “universal” (= current directions on both sides or without polarity ), the equivalent term “ monodirectional ” (= current flow only in one direction) is recommended here instead of “unidirectional”.

Materials science

With regard to fiber composite plastic laminates, the term describes the given fiber direction of the prepreg , so here the fibers are only oriented in one direction. The main term for prepreg material, in which the fibers generally only run in the 0 ° direction (warp thread), is tape or unidirectional prepreg.

Printing technology

In printing technology for EDP printers or other similar office machines, the term also describes a method in which the printing unit only prints characters on the paper when moving from left to right and only performs a carriage return on the way back .


  • Volker Jung, Hans-Jürgen Warnecke (Hrsg.): Handbook for telecommunications. Springer Verlag, Berlin / Heidelberg 1998, ISBN 978-3-642-97703-9 .
  • Manfred Broy, Otto Spaniol (Hrsg.): VDI-Lexikon Informatik und Kommunikationstechnik. 2nd edition, Springer Verlag Berlin Heidelberg, Berlin Heidelberg 1999, ISBN 978-3-642-46846-9 .

Individual evidence

  1. Manfred Flemming, Siegfried Roth: fiber composite construction properties. Springer Verlag, Berlin / Heidelberg 2003, ISBN 978-3-642-62459-9 , pp. 113-117.
  2. Hans Peter Degischer, Sigrid Lüftl (Ed.): Lightweight construction. Principles - material selection and production variants, Wiley-VCH Verlag GmbH & Co KG a. A., Weinheim 2009, ISBN 978-3-527-32372-2 , pp. 120-126.

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