In article ,
Jim Lux wrote:

Somewhat tricky..

Two crossed dipoles fed with the correct phasing is very close to that.

The tricky part, I believe, is maintaining the correct phasing between
dipoles over a sufficiently wide frequency range.

For narrow-band applications, using an additional quarter-wavelength
feedline phasing section would do.

For somewhat wider-band applications (say, 2:1 frequency range) a
broadband 90-degree hybrid ought to work... Minicircuits sells some
such.

I'm not at all sure how to do this for an antenna intended to cover
everything from VHF low-band up to the 700 MHz end of the new UHF
channel range. This is more than a full decade of frequencies... is
there a single broadband 90-degree hybrid that can do the job?

It feels like it might be necessary to split the signals into multiple
bands (VHF / UHF at least, possibly VHF-low / VHF-high / UHF) and then
do the phase shifting on each band individually and then recombine.
Pretty complex...

Or is there an approach I've missed?

--
Dave Platt AE6EO
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