Ham G3PTN design has developed a two-element antenna, which he called "Zygl-beam". She is an active antenna with power. Both are made in the form of open rectangles, arranged in one plane.
As a result of experiments to increase the efficiency of the antenna, the author has developed her three-element option scheme which (for the range of 14 MHz) shown in the figure. Three-element "Zygi-beam, according to the author, is much more concerned with radiation back and forth (up to 20 dB) and high gain (up to b dB). The input impedance of the active vibrator is 65 Ohms.
As a third element applied passive reflector, shortened by using two inductors (for the range of 14 MHz resonant frequency reflector of 13.6 MHz). Each coil is wound on the frame 19 in diameter and 100 mm long and consists of 56 turns of wire with a diameter of 1.2 mm, the winding turn to turn.
As the feeder of the antenna used 75 Ohm coaxial cable from the balun transformer. to configure the antenna, the author recommends in two stages. First configure the active elements, then add a reflector. Using any signal with horizontal polarization (for example, the signal of a local Amateur radio station), seeking better relations radiation back and forth, adjusting the length of the reflector. Adjusting the reflector, rebuild the item In to a frequency that is approximately equal 15,35 MHz. The ratio of the radiation back and forth should be increased. In conclusion, validate the setting element L. removing the dependence of VSWR with frequency within the range.
Setting the active elements of the antenna should be carried out according to the method, which told in "Radio", 1975, No. 8, pp.
Literature
Publication: N. Bolshakov, rf.atnn.ru