Delta loop

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A delta loop (also delta loop ) is a whole-wave loop (wire length = wavelength) in the shape of a triangle. It can consist of just one or more powered elements (radiators). In addition, one or more parasitic elements (directors and reflectors) can increase the directivity and the associated antenna gain .

construction

Usually the delta loop is built up in a standing position with the point pointing upwards. This has the advantage that only one mast or high fastening point is required for the construction. If you build it up with a point downwards, it requires more effort, but you achieve a greater relative height above the ground, which favors a mostly desired flat radiation . Occasionally they are also set up horizontally, parallel to the ground, possibly with a parasitic element also lying underneath, which serves as a reflector. Such lying delta loops are optimized as steep radiators.

The material used for the antenna is usually aluminum or copper wire , which is stretched as a triangle; pipes are used less often. As mast material, wood and GRP are preferred over metal constructions, as the latter tend to negatively influence the radiation properties of the antenna.

Delta loops, although they have a directional effect , are usually permanently installed.

properties

The delta loop is derived from the quad antenna and tends to have comparable properties. When using directors and reflectors as well as with several radiators (two or more phase-shifted elements one behind the other) the directional diagram changes to a lobe. Due to the additional (active or parasitic) elements, the quad antenna achieves a relatively high antenna gain and a stronger directivity in the tuned frequency range.

While the loop fed must have a circumference that corresponds to one wavelength, the length of the directors is slightly shorter and the length of the reflector is slightly longer. The exact lengths are influenced by the ambient conditions, so coordination at the installation site is usually necessary. The location of the feed (a tip or a wire center) influence the polarization. A distinction is made between horizontal and vertical polarization.

The delta loop is a particularly quiet antenna because of its electrically closed structure. It receives less interference than open antenna shapes, for example the typical crackling noise during statically charged rain or snowfall is at least significantly less. Even when transmitting, it significantly reduces the interference from electronic devices in the neighborhood, which are often susceptible to this due to technical and structural inadequacies. Even when mounted at a relatively low height, it is considered a good flat radiator and is therefore particularly suitable for long-distance connections (DX). Since it generates a certain amount of scatter polarization in addition to the desired polarization , it is less sensitive to fading , which is particularly advantageous for intercontinental connections.

With horizontal loops you have an ideal steep radiator, which is particularly suitable for loud and stable close connections.

history

The radio amateur W6DL proposed this type of antenna, which he derived from a quad antenna, in 1968 and called it delta loop. In the following years, many radio amateurs experimented with this initially theoretical model and demonstrated its practical usability and qualities, as well as developing various improvements and variants.

application

Delta loops are mainly used in amateur radio as a less complex alternative to quad antennas. Because radio amateurs have extensive experience and literature on this type of antenna, they are usually built by radio amateurs themselves and are still being developed today.

literature

  • Karl Rothammel u. Alois Krischke: Rothammels Antennenbuch , Franckh-Kosmos Verlag Stuttgart, 11th edition, 1995, ISBN 3-440-07018-2
  • K. Weiner DJ9HO: The Cubical Quad and its special forms. DARC-Verlag, Baunatal 1999