It is a high-gain eight-element antenna with two powered elements and a quadruple reflector. With a boom length of about 480 cm, the antenna has a gain of about 13.7 dBi. It was created according to the design of G2BCX (2m) by recalculating in the NEC 2 program and flashing it in a real environment.
The elements, with the exception of both powered elements - compound dipoles, are mounted on the boom conductor. It is convenient to make them on a preparation that we can make on a wooden board. The bending radius is 37 mm. All elements are made of AlMgSi with a diameter of 12 mm.
The reflector wall is composed of four reflectors. The inner pair (closer to the boom) is 287 cm long, the outer pair 292 cm long. Such a reflector gives much better results than a single or double.
Folded dipoles are placed in the plane of the boom. We achieve this by attaching them to the PTFE holders in the tool and fixing the holders above the boom. The ends must be treated against water penetration, preferably with a waterproof box.
All elements on the boom-e have a constant distance - 675 mm. This is a change compared to the original design, which was created by simplifying the modeling, when only the lengths of the elements were changed, not the spacing between them. We can attach them in one of the usual ways - in the case of a boom with a square profile (this is how G7OGN handled it), preferably through the boom.
Dennis gives the impedance of the two phased compound dipoles as about 450 ohms. He implemented the adaptation to 50 ohm with a beta-match at a distance of L/2 from the power point. This solution allows you to set a minimum PSV, je nutné nájsť len presnú polohu skratovacej spojky. Existuje ešte jedno riešenie – použiť balun 9:1.
The antenna met Dennis's expectations in every aspect - electrical and mechanical. In his "windy QTH“ vydržala už niekoľko vetrov o rýchlosti viac ako 135 km/h….