Small-sized two-element Sigma-Yagi. Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Small-sized two-element Sigma-Yagi. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / HF antennas

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A small two-piece Sigma-Yagi proposed by Peter Schmidt, DL9JFT, would require a few meters of steel pipe, perlon cable, antenna cable and four fiberglass sticks to make. As can be seen from Figure 1 (dimensions are for the 20-meter band, in square brackets - for the 10-meter band, and in round brackets - for the CB) the supporting traverse is made of Pg21 steel pipe with a diameter of 28 mm.

At the ends of the traverse, two transverse steel pipes Pg11 with a diameter of 19 mm are welded. Sticks made of glass fiber or another material with good insulating properties and withstanding high mechanical loads are passed into these crossbars. This design forms a mounting system for a sigmoid vibrator and a reflector made of an antenna cord and stretched with 3 mm perlon cables (see figure). Antenna tuning for minimum SWR is performed by changing the length of the vibrator web. To do this, the ends of the vibrator with a length of about 200 mm are left hanging freely as shown in the figure.

(click to enlarge)

The author has achieved a minimum SWR of 20 for such antennas for the 1,2 m and MW bands. The 20m antenna was located in the attic of a house with the main radiation oriented to the east, while the author received good reports from LA, P29, JA

Author: Peter Schmidt, DL9JFT; Publication: N. Bolshakov, rf.atnn.ru

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