The eight-element antenna type Wave channel
Czech radio OK1DE designed eight-element antenna of type "wave channel", which is effective in the range 144-146 MHz. Technical characteristics of the antenna are shown in the table, the curves of input impedance range is shown in figure 1, and the directivity in the horizontal plane in Fig.2.
Technical data antenna The number of elements 8 Gain (compared with conventional dipole),11-12 dB The weakening of the posterior lobe, dB 14±16 The ratio of the traveling wave 0,4-0,7 Maximum length, m 3,81 Maximum width, m 1,135
The device of the antenna and its dimensions are shown in Fig.3. Dimension values are in mm. During the construction of the antenna with dimensions that are given outside the brackets, its input impedance will be equal to 300 ohms. In that case, if you must have the antenna impedance 150 ohms, some the size of its change and are given in parentheses. Material for the manufacture of the antenna are dural tube: for all elements with a diameter of 10 mm, and for Rei, which reinforced elements with a diameter of 28 mm.
In the active antenna is used the folded dipole. To bend the vibrator easiest way cold way as follows. Solid wood carve two rollers with a diameter of 43 mm and strengthen them on a thick Board. The distance between the centers of the rollers shall be 900 mm. the Phone, designed for the vibrator is applied to the rollers, strengthen that it has not moved and bent around the circumference of the rollers.
The antenna elements to strengthen Rei M3 bolts as shown in Fig.4. To avoid deterioration of the antenna must be sure to adhere to all the dimensions specified in Fig.3, and also to observe the thickness of the tubes and a method of bonding elements and Rei.
To make it possible to apply for feeder antenna the most common cables with a characteristic impedance of 75 ω (RK-1, RK-3), you must attach the loop to the vibrator antenna with an input impedance of 300 ohms U - knee (Fig.5,a), simultaneously with the transformation of the input impedance of the antenna will be to symmetricality her. Transformation of the input impedance of 150 Ohm antenna is carried out using the transformer, made of cable.
Such transformers are described in the article Kharchenko and Isupova "Incomplete zigzag antenna" ("Radio", 1965, No. 1, pp. 24-27 and 4 page tabs in the log). Length lтр transformer to the antenna is 342 mm. balancing the antenna feeder from the transformer is routed through the pipe loop of the vibrator to the point of zero potential (Fig. 5,b). The outer insulating sheath of the cable is not removed. In this case, the folded dipole is easier to attach to Rei open-side-up (i.e., the party, joined the ends of the transformer).
Publication: N. Bolshakov, rf.atnn.ru