For radio Amateurs living in densely populated urban areas, an important parameter of the antenna becomes her "invisible" presence to others. The proposed antenna has good electrical parameters and is designed as a two-wire line similar to the line relay, which take place on the roofs of most houses and between them. It is desirable to use the same materials and methods of attachment as that of the speaker line.

It is based on the J-shaped antenna described in C. Rothammel.

Invisible antenna

Figure:

1 - movable short-circuiting jumper, with her help, the antenna is tuned to resonance at the desired frequency.

2 - "X-X" is the point of connection of supply antenna coaxial cable. Changing their position in relation to the jumper, making minimum COP8, take the value 1 at the resonant frequency of the antenna for cables with any wave resistance.

3 - jumper connecting the emitters of the antenna.

4 is a half-wave radiating elements of the antenna. If they do differ somewhat from each other in length (about 2-3%), broadband antennas increases.

Author: Gennady Trees (UX5UO), Kyiv; Publication: N. Bolshakov, rf.atnn.ru

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