[50mhz] Good gain verticals?

[mweisbergs at juno.com]

On Mon, 30 Jul 2007 08:35:33 -0600 "Bill W5WVO" <w5wvo at cybermesa.net>
writes:

> in the active ionospheric layer. BUT... I've never seen any results 
> from a  side-by-side test using a horizontal and vertical antenna of
the 
> same gain  (dBi) at the same elevation above ground during an E opening
to see 
> if this is  really true. Has anybody here ever actually done this, or
something 
> approximating it?

There was a study done in the 50's, hosted by Oliver P Ferrel, an editor
of CQ Mag. I'll see if I can find it in "my archives"


> The reason for my skepticism is that sporadic-E couds are very  highly
charged, 
> very planar (i.e., flat), and very thin -- all compared to the F 
layer, which 
> is structured very differently and refracts signals gradually back  to
earth. 
> E-clouds tend to act more like reflectors (mirrors) than refractors. 
The 
> flatter and more highly charged the surface of the E cloud is, the 
less  polarity distortion should take place. Theoretically.  :-)

I don't subscribe to this... thick or thin, refracted or reflected, the
"bounce" results in a randomized polarity, whether the bounce takes place
terrestrially or in the ionosphere. A more highly charged cloud (greater
ion density) results primarily in stronger signals and a higher MUF.
That's why, when the clouds are really charged, 2m opens up.

 
> Which would imply that a horizontally polarized antenna of the same
gain and  same elevation as a vertical might work better during strong 
sporadic-E  openings (assuming, as is the case, that most stations are
also  using 
 horizontally polarized antennas for DX work).

A more viable explanation regarding the apparent superiority of
horizontal over vertical during E-skip is in the nature of the skip.
Assuming the textbook skip distance of 1200-1400 miles for a single hop,
the E signal approaches the antenna at a far steeper angle than it does
during F skip. When that skip shortens up to several hundred miles, the
angle is steeper yet and interesting things happen. Indeed, I have often
experienced -- while trying to peak a signal by turning the beam -- the
situation of very little change in the signal, certainly not the usual
20db F/B ratio. The reason is that more of the signal is coming down on
the driven-element than is coming across the directors. In other words,
I've got a rotating horizontal dipole. That same signal, approaching a
vertical antenna, is mostly in its dead-zone, hence the pronounced
difference in reception.

Guys with az-el rotors might try elevating their antennas during a
short-hop session and see what difference it makes.

An interesting historical note... back in antiquity, before the Brits got
6M, we would work them 6M/10M crossband (full duplex!) and I, for one,
was getting decent signal reports. Many if not most of the G's were using
their TV antennas to feed their converters and those were all vertically
polarized with moderate gain.

Bud K2YOF