Topband: Sloper debate

[Greg - ZL3IX]

>
> Why Greg? A 1/4 wl slopper isn't much different than an
> inverted V.

> The slopper has as much current into
> the tower at the feedpoint as it does in the thing people
> call the antenna.

Exactly, and that's why it IS better than an inverted Vee.  Of course, the
more horizontal you can make the wire, the less cancellation of the fields
due to the currents in the tower that occurs, and the better the thing
works.  It's then like an inverted L with the feed at the bend instead of
the bottom.

Even better is not using the wire at all, but to replace it with a moderate
sized isolated yagi with a loading coil to bring it to resonance, as in the
RadCom article.  ("Top-Drive for the Lower Bands", G3LNP, RadCom April and
May 2002)  Then all the power goes into making a vertically polarised
signal, and none is "wasted" in the horizontal component.

In confined spaces, the sloper and its other top feed variants, may be
easier to get going with reasonable efficiency than a bottom shunt fed
tower, as the current at the base is generally lower with top feed, and the
degenerative effect of a poor radial screen is less.  I'm not saying that
radials aren't beneficial, just that they are not quite as critical as when
the feed is at the base.


73, Greg, ZL3IX