9-element Swan antenna at 144 MHz. Scheme, description

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9-element Swan antenna at 144 MHz. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / VHF antennas

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The antenna, the design of which is given below, is proposed by Gajarski, HA4YD. It has a gain of 18 dB in the range of 144-144,5 MHz, 17,75 dB at 145 MHz and 17,4 dB at 146 MHz. As can be seen from the figure, this antenna is a hybrid of a wave channel and a log-periodic antenna.

Fig.1 (click to enlarge)

The input impedance of the antenna is 110 ohms. To match with a 50-ohm coaxial cable, a short-circuited loop is used, the design of which is shown in Fig. 2. Attention should be paid to the U-shaped jumper of the log-periodic part of the antenna, the length of which is 178 mm.

Ris.2

Antenna elements are made of aluminum tubes with a diameter of 6 mm. The bearing traverse is made of a pipe with a diameter of 30 mm. The holders of the split vibrators are made of insulating material (Teflon, fluoroplastic, fiberglass, plexiglass, etc.), and for solid vibrators - of aluminum (Fig. 3).

Fig.3. Design of holders for split (top) and solid (bottom) elements (click to enlarge)

Literature:

Gajarski, HA4YD: SWAN-Antenne, Radiotechnika 24 (1974), H.5, S.207 and 208

Author: W. FAULHABER - Y28RL/Y38ZL, Translated from German by N. Bolshakov, RA3TOX; Publication: N. Bolshakov, rf.atnn.ru

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