TopBand: Rotary Flag?

[Earl W Cunningham]

Dear Peter, VK3APN, OM,

I nreference to your question about a suiteable mast to support a
rotatable Flag antenna, I added a 20.5-foot, 2-inch diameter mast to my
software Flag model made of #14 gauge wire.  I placed the mast midway
between the two vertical sections of the Flag and 6 inches off to the
side so that the horizontal sections of the Flag were clear of the mast.

The presence of the mast has only a small effect on the Flag.  This
effect was corrected by increasing the termination resistance value from
950 ohms to 965 ohms.  The Flag still looked good from 1.8 to 7.5 mHz.

I feel that a support frame made similar to the "X" frame for a cubical
quad element could be constructed to support the #14 Flag wires.  Four
13-foot fiberglas or bamboo quad spreaders could be used if extended at
the mast end by about 3 feet each.

I shortened the mast in my model to 13.5 feet (which is about the height
needed if the quad construction method is used) and results were about
the same as before with the 965-ohm termination.

I've also modeled a diamond-shaped compact receiving antenna based on the
same principle as the Flag and Pennant.  Is seems to me that the diamond
configuration would also be useful as a rotatable antenna using quad-type
construction.  I haven't yet optimized the model, but when I do I'll post
the dimensions and results.

73, de Earl, K6SE


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