[TowerTalk] 80m dipole with open-sleeve parasitic

[Rick Karlquist]

knormoyle at surfnetusa.com wrote:
> If you're saying a single wire with LC match can have same bandwidth and
> lower loss, I guess I find that hard to believe?

That is not apples vs apples.

If you make the antenna out of two wires, but simply tie
them together to make a "fatter wire", then the LC network
wins.  It might still win with a single wire, because the
fatter wire doesn't help the bandwidth all that much.

The reason why a lumped element network is more broadband
that any sort of distributed structure is that the inductance
or capacitance of a distributed structure increases with frequency,
which decreases the bandwidth.  The inductance or capacitance
of a lumped element is constant, by definition.

> Am I missing a loss calculation in open sleeve designs?

Open sleeves, like linear loading, are not lossless, or even
necessarily less lossy than good lumped elements.  There is a
lot more lossy wire in a parasitic element than in a coil.

>
> -kevin
> ad6z

See:

QST Oct 1986 P27
QST Jun 1985 P42
QST Jul 1984 P45
QST Apr 1983 P22

available at arrl.org

Rick N6RK