Antenna coupling

Center-fed half-wave dipole (λ / 2) in the upper area with a short-circuited λ / 4 stub line for coupling the coaxial line to the dipole in the lower area of ​​the picture.

The antenna coupling referred to in the antenna art , a method, an antenna electrically with the source or reception level of a radio device to be connected. The different line wave resistances of the antenna and the transmission line between antenna and radio device are matched to one another by means of impedance matching .

The coupling can take place through various adaptation structures . In addition, a balun can be used to convert between a symmetrical signal feed and an asymmetrical signal feed. This conversion is necessary, for example, if an antenna with symmetrical signal feed is to be connected to an asymmetrical cable such as a coaxial cable .

In the event of a mismatch in the antenna coupling, standing waves occur ; this is associated with an increase in the standing wave ratio (SWR), which means that the full power cannot be transmitted to the antenna. In the case of transmitter systems, this means that the maximum power is not emitted, the difference is reflected to the transmitter stage and can lead to thermal damage there. In the case of receiving antennas, incorrect antenna coupling leads to a reduction in the received signal at the input of the receiver.

literature

• Alois Krischke: Rothammels Antennenbuch . DARC Verlag, ISBN 3-88692-033-X .
• Ekbert Hering, Klaus Bressler, Jürgen Gutekunst: Electronics for engineers . Springer-Verlag, ISBN 3-540-63853-9 .

Web links

• Feedline. Retrieved May 15, 2014 .