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Mainflingen cross dipole
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The dipoles
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technical description:
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The results have been so convincing, that a preliminary decision in favour of the antenna was made.
Many more obstacles had to be removed, in particular financial and environmental issues, as the antnna is located in the middle of a forest, finally the green light for erection of the antenna was given.
Technical description:
The cross dipole in Mainflingen is an ionospheric antenna which consists of five guided supporting masts and the two horizontal dipoles arranged orthogonally atop of the masts.
The design of the antenna including the supporting masts and the guys can be seen as plots of the computer model.
The cross dipol has a circular polarisation, which means that the wave of one dipole lags the wave of the other dipole by 90 degrees. A right or left rotating field occurs depending on which dipole lags. The sense of rotation is important due to the properties of the ionosphere: only with one sense of rotation the waves are reflected. With the other sense the waves are let through the ionosphere. These are the ordinary and the extraordinary wave.
Standing below the antenna and looking into the direction of the ionosphere a right sense of rotation is needed to excite the ordinary wave.
During measuring tests this behaviour was demonstrated by reverting the sense of rotation. A difference of approx. 20 dB was noted for the reception field strength.
to be continued on > 4E
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computer model - perspective view
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computer model - top view
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Mainflingen cross dipole
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