The use of antennas with different ranges with a parallel-connected vibrators are very attractive, as it allows to use a common feeder. But (in practice) such antennas, arranged in a single plane, operate satisfactorily only at low frequency ranges.

At the same high frequency ranges of their efficiency due to mutual influence is greatly diminished. W6P1Z proposed to use a combination of two antennas with different polarization, which allows to obtain a very small mutual influence and good directivity in the vertical plane for both frequency ranges.

Combined antenna KB

On the radio UV3TC has been tested combo antenna on the ranges of 3.5 and 28 MHz. The antenna consists of horizontal and vertical dipoles are parallel (see figure). The diameter of the pin is equal To 15 mm. dipole band 3.5 MHz and counterweight used copper wire with a diameter of 3 mm Coaxial cable used type RK-75-4-15.

Antenna installed on the roof of a five-story building. Suspension height above the roof of 3.5 m.

When tested in the range of 3.5 MHz according to the conventional dipole field strength is not detected. On the 28 MHz range compared to conventional antenna Ground Plane, there was a slight distortion of the directional pattern in the horizontal plane.

The structural performance of the vertical dipole is easier than antenna type "Ground Plane".

Author: Ing. V. Makarov (UV3TC), Gorky; Publication: N. Bolshakov, rf.atnn.ru

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