All-wave amateur antenna. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / HF antennas
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The antenna of a French shortwave radio amateur is described in the CQ magazine. According to the author of the design, the antenna gives a good result when working on all shortwave amateur bands - 10 m, 15 m, 20 m, 40 m and 80 m. It does not require any particularly careful calculation (except for calculating the length of the dipoles) or fine tuning. It should be set immediately so that the maximum of the directivity characteristic is oriented in the direction of preferential connections.
The feeder of such an antenna can be either two-wire, with a wave impedance of 72 ohms, or coaxial, with the same wave impedance. For each band, except for the 40 m band, there is a separate half-wave dipole in the antenna. On the 40-meter band, the 15-meter band dipole works well in such an antenna.
All dipoles are tuned to the middle frequencies of the respective amateur bands and are connected in the center of it in parallel to two short copper wires. The feeder is soldered to the same wires from below. Three plates of dielectric material are used to isolate the center wires from each other. At the ends of the plates, holes are made for attaching the wires of the dipoles. All wire connections in the antenna are soldered, and the feeder connection point is wrapped with plastic tape to prevent moisture from entering the cable. The calculation of the length L (in m) of each dipole is carried out according to the formula
L=152/fcp,
where fav is the middle frequency of the range, MHz.
Dipoles are made of copper or bimetallic wire, guys are made of wire or cord. Antenna height - any, but not less than 8,5 m.
Literature
- "CQ", July 1959
- Radio No. 10 1957, p.61.
Publication: cxem.net
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