Rubber sausage
As rubber sausage in is radio operator -slang an inductively extended, mechanically short rod antenna with quarter wave resonance designated (coil antenna), the (electrical) loading coil (mechanical reduction allows) forms as a single-layer cylinder coil, the whole antenna. To protect and increase stability, this wire helix is completely enclosed in a rubber or plastic cover.
This type of antenna is mainly used in handheld radios to make the antenna short. However, the shortness of the antenna also reduces the radiation resistance and thus the efficiency considerably. Antennas that look similar are also found in WLAN devices; Due to the higher frequency and the resulting short wavelength, inductive lengthening is not necessary here, which is why there is a complete, unshortened coaxial dipole with correspondingly good efficiency inside this antenna.
Such shortened rod antennas are not to be confused with helical antennas , although they are often referred to in the same way. The difference is that the helix in the rod antenna is only used for inductive elongation and has small dimensions compared to the wavelength . Inductively elongated rod antennas therefore radiate like normal dipoles across the direction of extension and not like helical antennas along it.
literature
- Alois Krischke: Rothammels Antennenbuch . 13th edition. DARC-Verlag, 2013, ISBN 978-3-88692-065-5 .