antenna filare a piramide

[IZ8XOV]

Ovvero "Pyramid Wire Beam" un'antenna forse poco conosciuta ma dalle caratteristiche interessanti. (alla fine dell'articolo metto anche uno italiano)

William R. Mest, WBØAOF, has tried numerous types of antenna systems on 80 meters but the pyramid antenna is, by far, the best system he has found for him. It actually looks like two delta loops, about the size of 40 meter loops, sloping in opposite directions. The entire wire length of the antenna is a full wavelength in a configuration that is doubled back on itself, then sloping in opposite directions. As can be seen, the wire crosses itselfs at the midpoint of the antenna. In the original article, the author chose 75-ohm coax but he stayed away from this direct feed system and used a quarter-wave 75-ohm coax cable: this pyramid antenna exhibits a characteristic impedance of about 90 ohms.

Keep in mind that a unilateral triangle is not absolutely necessary to make this antenna work but the height of the horizontal sections above ground should be a minimum of 10 feet.

Radiation is mainly off the slanting wires: at lower angles, radiation is strongest in the direction A-B, weakest in C-D. In other words, the antenna is great for short distance contacts and very good for DX contacts.



Qui a seguire l'articolo apparso su Air Radio Rama

http://air-radiorama.blogspot.it/2011/12/la-maxiwhip-piramidale.html