Modernization of antenna counterweights. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / HF antennas
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Once again, the modernized multi-band vertical antenna UW4HW (see "Radio", 1981, No. 9) has four exponential counterweights 5,1 m long, the axes of which form an angle of 120 ° with the mast (Fig. 1). Each counterweight is made of six wires with a diameter of 1,5...2 mm (Fig. 2). The wires at the ends of the counterweights are twisted together, and their joints are soldered. In the middle part, they are attached with a PEV-2 1,0 wire to a spacer ring (outside) - a sports hoop made of a duralumin tube with a diameter of 18 mm. The wires and the ring at the points of contact with each other are pre-wound with three or four layers of PVC insulating tape. The hoops should be at a distance of 1,6 m from the base of the emitter.
The upper ends of the counterweights are fixed on four M6 bolts, welded under the base of the vertical radiator to a grounded carrier mast (steel pipe with a diameter of 35 mm), electrically connected to each other and to the feeder braid.
The lower ends through an insulator - a fiberglass plate measuring 150X50X3 mm - are attached to guy wires that are tied to the roof of a two-story house.
The input impedance of the manufactured antenna is about 75 ohms, the SWR remains equal to 1,05 ... 1,2 at frequencies from 14 to 30 MHz.
For long-distance connections, according to correspondents, the audibility when working on the described antenna is 2 ... 3 points better than when connecting the W3DZZ antenna suspended at the same height.
Author: Y. Chernyatynsky (UT5UB) Donetsk; Publication: cxem.net
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