Rubber ducky antenna

As the rubber sausage in Funker slang an inductively extended, mechanically short rod antenna with quarter-wave resonance denoted ( coil antenna ), where the ( electric ) loading coil (allows mechanical shortening ) as a single-layer cylindrical coil forms the entire antenna. To protect and increase the stability of this wire helix is completely in a rubber or plastic sheath. Applications of this antenna shape mainly in portable radio devices, in order to make the antenna short. However, the radiation resistance and thus the efficiency decreases considerably by the shortness of the antenna. Even with wireless devices, there are similar-looking antennas, due to the higher frequency and consequently short wavelength is not an inductive extension necessary, so here is the inside of this antenna, a complete unabbreviated Koaxialdipol with correspondingly good efficiency.

Such truncated rod antennas are not to be confused with helical antennas ( helix antennas), though they are often referred to as well. The difference is that only the coil of the inductive extension is used for the rod antenna, and with respect to the wavelength has small dimensions. Therefore Inductive extended rod antennas radiate as ordinary dipoles transverse to the direction of extension and not as helical antennas along this.

• Antenna design