When multiple vibrators are arranged in a row and are excited simultaneously, the direction of maximum radiation is not changed, but significantly decreases the width of the main lobe of the radiation pattern. This antenna has a higher gain compared to the single half-wave dipole. The more radiating elements in the antenna, the narrower main lobe is obtained diagrams and a large - gain. If the number of items exceeds two, the chart appear small side lobes.
Aerial upgrade is to ensure that the ends of the dipole through a short-circuited quarter-wave segments are connected half-wave vibrators. A short-circuited quarter-wave segments (loops) rotate the phase by 180° and constitute a parallel resonance circuit connected between a half-wave vibrators. The gain of the antenna relative to half wave dipole is 3.4 dB. The antenna is fed by a current, and therefore, its input impedance is 300 Ohms. This allows the use of a symmetrical power line.
The length of each vibrator l=0,485 l. The length of the loop (two-wire belt in the dielectric) l=0,205 l.. Length cables using cable - l=0,165 l.
I use a three-element collinear antenna located at an angle of 45°, the height of the suspension lower end - 6m, the upper 150 m (very good QTH near - TV-mast).
The leaf antenna is made of bimetal with a diameter of 4.2 mm, the loops are made of jumper wire (used on the PBX), twisted with slight tension and wound in coils, wrapped by a dielectric (see figure). The beginning of wires in the Bay are soldered together, and the ends are soldered to the vibrators. The bandwidth of the loop is about 200 kHz, the falloff at edges is 1 dB, which is sufficient for the 160-meter band. Structurally, the plume worn on the canvas of the antenna and is secured between the insulators. The antenna is powered long, about 80 m coaxial cable with a characteristic impedance of 75 Ohms. VSWR at resonance is 1.05, and the edges of the range is 1.8. If sustained all dimensions, the antenna is obtained tuned for mid-range setting is to configure the circuits to resonance at the middle of the range that is most convenient to make the instrument XI-42.
The antenna used for two years. During the operation of the antenna held SSB QSO with many DX stations - VE, VK, N, 8P and others. Used transceiver UW3DI-II, SU-19 in the output stage.
Literature
1. Bieńkowski 3., Lipinski, E. Amateur antenna LW and УSW:
The Handbook. - 1983. - Page 283.
2. Rothammel K. Antenna: A Handbook. - 1979. - P. 198.
Author: N. Bags (RZ9YN), Altai Krai. Annunciation p-n, p steppe Lake; Publication: N. Bolshakov, rf.atnn.ru