HB9CV antenna
The HB9CV antenna or Swiss antenna is a fully fed antenna with two elements in the form of two dipoles of unequal length . It was developed and described by radio amateur Rudolf Baumgartner (callsign HB9CV) in the 1950s. The antenna found its way into Rothammel's antenna book . The main area of application is the ultra-short wave range , especially for portable direction finders . The antenna is also often used in zoology for radio direction finding of wild animals equipped with tracking devices .
Due to the unequal lengths of the two dipoles, a pronounced directional effect is achieved . With the arrangement as in the adjacent picture, most of the transmission energy is radiated upwards. The best reception comes from this direction.
The antenna consists of three electrically connected metal rods in the form of a horizontal "H" as shown in the adjacent figure. The upper metal rod is shorter than the lower metal rod with the length λ / 2 by a factor of 0.92, where λ is the wavelength . Between the upper, shorter metal rod, which functions as a dipole , and the lower, longer metal rod, which serves as a reflector, there is a connecting line (black, step-shaped line) isolated from the central rod with connection points at a distance of λ / 16 from the central axis.
The power is supplied via a coaxial cable , the inner conductor of which is connected to point "1" and the outer conductor to point "2". A trimming capacitor is used to adjust the coupling , which is set so that the standing wave ratio is below 1.2.
The original form of symmetrical feed is only rarely used today because coaxial cables are usually used as connection cables.
The antenna gain of this antenna design is in the range from 4.1 dBd to 4.2 dBd and is higher than that of all other antennas made of just two elements. The ratio of antenna gain to material expenditure and space requirement is also favorable, the only disadvantage is the somewhat more complex feed into both elements. Correspondingly dimensioned Yagi-Uda antennas can achieve a higher antenna gain than a single HB9CV antenna with more than 3 elements and correspondingly more effort.
literature
- Rudolf Arthur Baumgartner: The HB9CV directional antenna . Kröner-Verlag, Stuttgart 1961.
- Karl Rothammel, Alois Krischke: Rothammels Antennenbuch . 12th edition. DARC Verlag, ISBN 3-88692-033-X ( online ).
