On 11/21/2014 8:22 PM, wrote:
Jerry Stuckle wrote:
On 11/21/2014 5:22 PM, Wayne wrote:

snip

Along the lines of a "testimonial"...
I once lived in the center of a state that had an active 75 meter net.
At one point I was asked to be one of the net control stations because
of my consistent strong signals within the net.

The secret? A 75 meter dipole at 20 feet with 100 watts.
On longer paths, of course, the "big boys" kicked my butt big time.

Gee, according to jimp, your antenna should have "sucked".

Which shows you are incapapble of understanding the difference between
NVIS propagation and skywave propagation or anything else that I wrote.


Nope, I understand them a lot better than you do. And his comments had
NOTHING to do with what you said. According to you, his antenna
"sucked". Period. No qualification.

If you did understand it, you would know that what he said is TOTALLY
consistant with what I wrote.

And once again you are trying to weasel out of what you said. Just like
a troll.

But then he isn't interested in facts that contradict his fantasies.

But then your aren't interested in facts that contradict your fantasies.


No, you aren't.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

Jerry Stuckle wrote:
On 11/21/2014 8:19 PM, wrote:
Jerry Stuckle wrote:

snip

I've also run dipoles - I got WAS on 75 meters from Iowa with an
inverted VEE running from 50' to near ground. And I had a strong signal
on the Iowa 75M SSB net.

I have lots of strong signal reports from around the country on 6M AM
running 3W into a 2 foot collapsible whip.

Of course it was at the height of sunspot cycle 19 and says NOTHING about
the effectiveness of the antenna.




Which has absolutely nothing to do with your comment about a dipole on
75 meters. But you're too stoopid to understand that.

But it has EVERYTHING to do with your comment about WAS.

But you are so enraged about being correct you can not understand that.



--
Jim Pennino

Jerry Stuckle wrote:
On 11/21/2014 8:22 PM, wrote:
Jerry Stuckle wrote:
On 11/21/2014 5:22 PM, Wayne wrote:

snip

Along the lines of a "testimonial"...
I once lived in the center of a state that had an active 75 meter net.
At one point I was asked to be one of the net control stations because
of my consistent strong signals within the net.

The secret? A 75 meter dipole at 20 feet with 100 watts.
On longer paths, of course, the "big boys" kicked my butt big time.

Gee, according to jimp, your antenna should have "sucked".

Which shows you are incapapble of understanding the difference between
NVIS propagation and skywave propagation or anything else that I wrote.


Nope, I understand them a lot better than you do. And his comments had
NOTHING to do with what you said. According to you, his antenna
"sucked". Period. No qualification.

My god you are delusional when you are raging.

If you did understand it, you would know that what he said is TOTALLY
consistant with what I wrote.

And once again you are trying to weasel out of what you said. Just like
a troll.

My god you are delusional when you are raging.


--
Jim Pennino

"Ian Jackson" wrote in message ...

In message , Wayne
writes


wrote in message ...


For those that do not have a firm understanding of what the chart of
dipole height over ground shows, I offer the following explanation.

The charts show, for a dipole antenna at various heights in wavelengths
over perfect, very good, average, and extremely poor ground, the gain
and elevation angle of the antenna main lobe.

The main lobe is where the majority of the energy is radiated.

To understand what the charts mean in the real world, first you have
to understand a little bit about propagation of RF.

For a dipole antenna, there are two modes of propagation that are
relevant,
and those are NVIS (Near Vertical Incidence Skywave) and skywave which
is sometimes called skip.

Both modes depend on the RF being reflected or refracted back toward
Earth by the ionosphere.

For NVIS mode, the RF is directed straight up, that is an elevation angle
close to 90 degrees is desired. The range of NVIS communications is on
the order of 50 - 650 km, depending on the state of the ionosphere. The
amateur bands where this is effective is limited primarily to the 160M
to 40M band, again depending on the state of the ionosphere. It is not
impossible to have NVIS communications on the higher bands, just much
less probable to happen.

For skywave mode, a low elevation mode is desired. Most of the literature
recommends angles of 30 degees or less. In this mode the RF "bounces"
at more obtuse angles, and with good conditions in the ionosphere, more
than once, providing communication over global distances. Skywave
depends heavily on the condition of the ionosphere and during sunspot
peaks often occurs well past 10M.

Now since a dipole with a main lobe at 90 degrees still has some gain
at low angles, though it can be 20 to 60 dB down from the main lobe,
when conditions are very good some stations can still be heard by
skywave mode, though it is a rarity and can not be depended on.

Conversely a dipole with a low elevation angle of the main lobe has some
gain at very high angles and can occasionly hear stations by NVIS mode,
but again it is a rarity.

The bottom line of all this is that if you desire NVIS communications,
you should mount your dipole at a height where the elevation angle is
close to 90 degrees while if you desire long distance communications
you should mount your dipole at a height where the elevation angle is
less than 30 degrees, or higher if possible.

If the required height is impractical at your location, then the
alternative is a ground mounted vertical or a close to ground mounted
ground plane antenna, which will have an elevation angle in the 20
degree range.

Along the lines of a "testimonial"...
I once lived in the center of a state that had an active 75 meter net. At
one point I was asked to be one of the net control stations because of my
consistent strong signals within the net.

The secret? A 75 meter dipole at 20 feet with 100 watts.
On longer paths, of course, the "big boys" kicked my butt big time.

# Despite the obvious theory, and over 50 years in amateur radio, I still
# find it hard to believe that, in real life, an 80m dipole at (say) 20'
# ever really outperforms (at any distance) one at (say) 100'. Given the
# choice, I know which one I would choose!

A 20 foot high 75 meter dipole wouldn't be my first choice for an antenna.
At the time, that was the highest supports I had available.

I just dusted off EZNEC and out of curiosity ran the plot for a 75 meter
dipole at 20 feet over "real" ground.
The max lobe was 9.36 dbi straight up at 90 degrees and a 3 db down
beamwidth of 99.4 degrees. The 3 db down points were at 40.3 degrees and
139.7 degrees.

So at least according to EZNEC, and my own personal experience for short
range HF communication on 75 meters, a low dipole is a pretty good choice.

On 11/21/2014 8:56 PM, wrote:
Jerry Stuckle wrote:
On 11/21/2014 8:19 PM, wrote:
Jerry Stuckle wrote:

snip

I've also run dipoles - I got WAS on 75 meters from Iowa with an
inverted VEE running from 50' to near ground. And I had a strong signal
on the Iowa 75M SSB net.

I have lots of strong signal reports from around the country on 6M AM
running 3W into a 2 foot collapsible whip.

Of course it was at the height of sunspot cycle 19 and says NOTHING about
the effectiveness of the antenna.




Which has absolutely nothing to do with your comment about a dipole on
75 meters. But you're too stoopid to understand that.

But it has EVERYTHING to do with your comment about WAS.

But you are so enraged about being correct you can not understand that.




Nope. It has NOTHING to do with a dipole on 75 meters - which is the
subject of this thread. You're just trying to derail the conversation
so you don't have to admit you're wrong.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

On 11/21/2014 8:58 PM, wrote:
Jerry Stuckle wrote:
On 11/21/2014 8:22 PM, wrote:
Jerry Stuckle wrote:
On 11/21/2014 5:22 PM, Wayne wrote:

snip

Along the lines of a "testimonial"...
I once lived in the center of a state that had an active 75 meter net.
At one point I was asked to be one of the net control stations because
of my consistent strong signals within the net.

The secret? A 75 meter dipole at 20 feet with 100 watts.
On longer paths, of course, the "big boys" kicked my butt big time.

Gee, according to jimp, your antenna should have "sucked".

Which shows you are incapapble of understanding the difference between
NVIS propagation and skywave propagation or anything else that I wrote.


Nope, I understand them a lot better than you do. And his comments had
NOTHING to do with what you said. According to you, his antenna
"sucked". Period. No qualification.

My god you are delusional when you are raging.


Read your own words. YOU said it - not me.

If you did understand it, you would know that what he said is TOTALLY
consistant with what I wrote.

And once again you are trying to weasel out of what you said. Just like
a troll.

My god you are delusional when you are raging.



Once again you refuse to discuss the topic. Instead of admitting you are
wrong, you are making ad hominim attacks. How like a troll.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

In message ,
writes
Ian Jackson wrote:

snip

Despite the obvious theory, and over 50 years in amateur radio, I still
find it hard to believe that, in real life, an 80m dipole at (say) 20'
ever really outperforms (at any distance) one at (say) 100'. Given the
choice, I know which one I would choose!

Try reading these:

http://www.qsl.net/wb5ude/nvis/
http://en.wikipedia.org/wiki/Near_ve...idence_skywave
http://www.w0ipl.net/ECom/NVIS/nvis.htm
http://kv5r.com/ham-radio/nvis-antennas/
http://www.arrl.org/nvis

Thanks, I'll certainly have a good read of those articles. But
regardless of what they say, in a typical amateur scenario, I still
reckon that at (say) 300 miles, an 80m signal from a dipole at 100' is
likely to be stronger than one from one at 20' (or even at 60').


--
Ian

El 22-11-14 3:01, Wayne escribió:


"Ian Jackson" wrote in message ...

In message , Wayne
writes


wrote in message ...


For those that do not have a firm understanding of what the chart of
dipole height over ground shows, I offer the following explanation.

The charts show, for a dipole antenna at various heights in
wavelengths
over perfect, very good, average, and extremely poor ground, the gain
and elevation angle of the antenna main lobe.

The main lobe is where the majority of the energy is radiated.

To understand what the charts mean in the real world, first you have
to understand a little bit about propagation of RF.

For a dipole antenna, there are two modes of propagation that are
relevant,
and those are NVIS (Near Vertical Incidence Skywave) and skywave which
is sometimes called skip.

Both modes depend on the RF being reflected or refracted back toward
Earth by the ionosphere.

For NVIS mode, the RF is directed straight up, that is an elevation
angle
close to 90 degrees is desired. The range of NVIS communications is on
the order of 50 - 650 km, depending on the state of the ionosphere.
The
amateur bands where this is effective is limited primarily to the 160M
to 40M band, again depending on the state of the ionosphere. It is not
impossible to have NVIS communications on the higher bands, just much
less probable to happen.

For skywave mode, a low elevation mode is desired. Most of the
literature
recommends angles of 30 degees or less. In this mode the RF "bounces"
at more obtuse angles, and with good conditions in the ionosphere,
more
than once, providing communication over global distances. Skywave
depends heavily on the condition of the ionosphere and during sunspot
peaks often occurs well past 10M.

Now since a dipole with a main lobe at 90 degrees still has some gain
at low angles, though it can be 20 to 60 dB down from the main lobe,
when conditions are very good some stations can still be heard by
skywave mode, though it is a rarity and can not be depended on.

Conversely a dipole with a low elevation angle of the main lobe has
some
gain at very high angles and can occasionly hear stations by NVIS
mode,
but again it is a rarity.

The bottom line of all this is that if you desire NVIS communications,
you should mount your dipole at a height where the elevation angle is
close to 90 degrees while if you desire long distance communications
you should mount your dipole at a height where the elevation angle is
less than 30 degrees, or higher if possible.

If the required height is impractical at your location, then the
alternative is a ground mounted vertical or a close to ground mounted
ground plane antenna, which will have an elevation angle in the 20
degree range.

Along the lines of a "testimonial"...
I once lived in the center of a state that had an active 75 meter
net. At one point I was asked to be one of the net control stations
because of my consistent strong signals within the net.

The secret? A 75 meter dipole at 20 feet with 100 watts.
On longer paths, of course, the "big boys" kicked my butt big time.

# Despite the obvious theory, and over 50 years in amateur radio, I still
# find it hard to believe that, in real life, an 80m dipole at (say) 20'
# ever really outperforms (at any distance) one at (say) 100'. Given the
# choice, I know which one I would choose!

A 20 foot high 75 meter dipole wouldn't be my first choice for an
antenna. At the time, that was the highest supports I had available.

I just dusted off EZNEC and out of curiosity ran the plot for a 75
meter dipole at 20 feet over "real" ground.
The max lobe was 9.36 dbi straight up at 90 degrees and a 3 db down
beamwidth of 99.4 degrees. The 3 db down points were at 40.3 degrees
and 139.7 degrees.

Maybe you confused directivity (D) with gain (G), or used a wrong
simulation paramater. A 20' high half wave dipole for 75m over
average soil has about D = 9 dBi. However because of the heat
dissipation into the soil below the antenna, the actual gain will be
around 3 dBi. In other words about 75% of the RF energy is dissipated
into the ground.

Is this problem? frequently not, as the link budget on 75/80m has
lots of margin under average conditions. Only onder worse conditions
(large D-layer absorption and/or high local noise level at the target
location) the one with the highest EIRP (=gain*power) will make the QSO.

Several years during JOTA we had a better then average NVIS antenna
for 80 m (with elevated reflection wires and a well fertilized
production field). With 100W input we get complaints about why we were
using a PA (we don't have one!). We decided to use a QRP TRX (10W) so
the FT101ZD could be used for 40 m. We had no complaints about the
signal.

So on average there is nothing wrong when using an NVIS antenna with
say 6 dB less performance (compared to an optimized one).

Nowadays we use a "downgraded version". about 3..4 dB loss of gain,
but it can be installed within 20% of the time required for the big one.



So at least according to EZNEC, and my own personal experience for
short range HF communication on 75 meters, a low dipole is a pretty
good choice.




--
Wim
PA3DJS
Please remove abc first in case of PM

Ian Jackson wrote:
In message ,
writes
Ian Jackson wrote:

snip

Despite the obvious theory, and over 50 years in amateur radio, I still
find it hard to believe that, in real life, an 80m dipole at (say) 20'
ever really outperforms (at any distance) one at (say) 100'. Given the
choice, I know which one I would choose!

Try reading these:

http://www.qsl.net/wb5ude/nvis/
http://en.wikipedia.org/wiki/Near_ve...idence_skywave
http://www.w0ipl.net/ECom/NVIS/nvis.htm
http://kv5r.com/ham-radio/nvis-antennas/
http://www.arrl.org/nvis

Thanks, I'll certainly have a good read of those articles. But
regardless of what they say, in a typical amateur scenario, I still
reckon that at (say) 300 miles, an 80m signal from a dipole at 100' is
likely to be stronger than one from one at 20' (or even at 60').

As 300 miles is at the upper end of NVIS and the lower end for skywave,
it would be a crap shoot.

NVIS distance is typically 30-400 miles.

--
Jim Pennino

Jerry Stuckle wrote:
On 11/21/2014 8:56 PM, wrote:
Jerry Stuckle wrote:
On 11/21/2014 8:19 PM, wrote:
Jerry Stuckle wrote:

snip

I've also run dipoles - I got WAS on 75 meters from Iowa with an
inverted VEE running from 50' to near ground. And I had a strong signal
on the Iowa 75M SSB net.

I have lots of strong signal reports from around the country on 6M AM
running 3W into a 2 foot collapsible whip.

Of course it was at the height of sunspot cycle 19 and says NOTHING about
the effectiveness of the antenna.




Which has absolutely nothing to do with your comment about a dipole on
75 meters. But you're too stoopid to understand that.

But it has EVERYTHING to do with your comment about WAS.

But you are so enraged about being correct you can not understand that.




Nope. It has NOTHING to do with a dipole on 75 meters - which is the
subject of this thread. You're just trying to derail the conversation
so you don't have to admit you're wrong.

Strawman arguement in an attempt to deflect the arguement from your
WAS statements.

--
Jim Pennino