Two American Amateurs Myers (W1FBY) and Asgrow (WA1LNQ) developed a compact three-element antenna for a range of 20 m. a Significant reduction in size achieved by the use of inductors and capacitive elements. All the main dimensions of the antenna shown in the figure.
The antenna is made of aluminum tube with an outer diameter of 32 mm. Frames for winding coils are connecting inserts 28.6 mm diameter, made of organic glass. Coils L1, L2 contain 23,5 coil, L3, L4 - 29 turns, L5, L6 - 26 turns of wire (enamel insulation) with a diameter of 1.4 mm. the length of the winding coils of 229 mm.
Capacitive elements are in the immediate vicinity of the coils. They are attached to the pipe at an angle of 90° to each other) cuts aluminum corners with a side of 19 mm and a length of 610 mi. The ends of the corners connect wire with diameter 1.5-2 mm. the Resonant frequency of the elements shown in the figure.
Approval of the vibrator antenna with feeder is made using the l-shaped device. The diameter of the tube used in the matching device, equal to 9.5 mm, length of 1016 mm. the Supporting insulating insert (not shown) made of organic glass. The maximum capacitance of trimmer capacitor - 140 pF. It is placed inside an aluminum box and isolated from the walls. With a tube condenser connect aluminum strip with a length of 152 mm.
Setup properly assembled antenna is to receive minimum SWR at the frequency to 114.1 MHz using the trimmer and position of shorting threads in the matching device. The value of SWR at the edges of the range must not exceed 2.
Literature
- "QST" (USA), 1974, N 10
- Radio No. 6, 1975
Authors: Myers (W1FBY) and Asgrow (WA1LNQ); Publication: www.cxem.net