Variable diameter antenna
 

Reading through the 20 meter J-Pole thread got me to thinking.

possible idiot question alert!

If a person was to design an antenna that had variable diameters, such
as a telescoping pole, or a thin whip antenna on top of a thicker pipe
as talked about in the J Pole, what effect would this have on the BW of
the antenna. Of course, (I think) it would be less than if the entire
antenna was made of one thick length. But I could be way off here. And
would it be calculable?

And could variable diameter be of practical use in antenna design?


- Mike KB3EIA -

And could variable diameter be of practical use in antenna design?

Tapered elements are common used in HF. They tend to load the antenna a bit,
thus shortening it. Some BW increase results as well.

At the other extreme, a continuously inverse- tapered antenna is quite broad in
bandwidth. Thus the Oliver Lodge, or 'bowtie' antenna, from 1897.

Old, old stuff.

73,
Chip N1IR