Antenna (Fig. 1) is a three-element YAGI with the Director and reflector, all three elements made in the form of shorter helical dipoles.
Fig. 1
Structurally, each of the elements is made of two glass fibre laminate ski poles length of 1.5 m each, fastened together by a metal tube of length 10 cm On the pole with a length of 3 m is wound on 5 meters insulated wire with a pitch of 2 mm. the Director and reflector are one piece of wire, the middle of which connects to the metal yoke. Fueled by the element in the middle is broken. The antenna tuning is done by changing the winding pitch in the middle part and the movement of elements on the boom.
This antenna, of course, plays a full-size YAGI (or, indeed, any shorter), but significantly (1-3 points) wins the GP or a half-wave dipole.
Author: V. Karasev (RB5EHS); Publication: krasnodar.online.ru/hamradio, www.cxem.net