Biconical antenna

The term butterfly antenna is used in German-speaking countries for several different antenna designs that are similar to all the open wings of a butterfly.

Schmetterlingsdipol

The more correct name of this half-wave dipole is Spreizdipol. The name Schmetterlingsdipol got this antenna by the translation of the English name Butterfly Antenna. It is a linear antenna for broadband applications, and despite the surface formation of the dipole antenna does not face. Electrically, this antenna acts like a wire antenna with Endkapazitäten, even if this wire is already trained as a surface. The bandwidth of such an antenna for DVB-T and UHF television reception is greater than the used frequency band.

Batwing -dipole

To enlarge the broadband behavior of the antenna yet, the Batwing antenna was developed from a Spreizdipol. A radiating element, the slot between the two surfaces at the ends connected to each other. Thus, this antenna has been one of the patch antennas.

The batwing dipole is formed by two shorted λ/4-Leitungen be connected to the feed points of a Spreizdipols. The surfaces of the Spreizdipols are then magnified to the line ends. The notches improve the current distribution over the " surface " and the frequency response. The compact surface can be replaced by a grid structure, the corners can not be rounded, and the result is the typical appearance of bat swing, which then gave the name of the antenna.

Turnstile and superturnstile antenna

To obtain an approximate omnidirectional pattern in the horizontal plane, two Batwing dipoles are assembled like a turnstile and two dipoles fed with a phase difference of 90 °. Since therefore circular polarization arises, two such crossed batwings are mounted above each other. A pair of antennas is equipped with an anticlockwise circular polarization and the second pair with right-handed circular polarization. The sum of the two antenna pairs causes in the far field, a vertically linearly polarized electric field. This construction was called the turnstile antenna.

For commercial use as a broadcasting antenna several such layers are stacked hammered. This design was named superturnstile antenna and is involved in many radio towers, as for example to see the Berlin radio tower and transmission tower in Muehlacker.