On Sep 12, 7:47*pm, "Frank" wrote:
"Art Unwin" wrote in message

...

A sloper antenna when resonant produces more gain
than a vertical dipole resonant at the same frequency.
True or false? prove it

Model parameters for sloping dipole: 60 ft at one end
13.3 ft at the other (45 deg slope). *Horizontal dipole
at 60 ft. *Length of both antennas 66 ft. *Sloping dipole
resonant at 7.225 MHz, same length horizontal 7.3 MHz.
Average ground parameters: conductivity 5 mS/m, and
relative permittivity 13. *Horizontal dipole maximum
gain off the sides (As expected). *Sloping antenna
double lobed pattern with maximum gain at 80 degrees
either side of lowest end. *Softwa Nittany's GNEC.

Simulation results:
..... snip ....

The original question said VERTICAL dipole , but you modeled a
HORIZONTAL dipole? Or was one of these just a typo?

FWIW, I modeled your horizontal dipole in EZNEC and came up with
slightly DIFFERENT results:
Resonant frequency about 7.335 Mhz
Resistance about 81 ohms
Max gain about 6.54 dBi at 30 degrees
I am INexperienced in using EZNEC and wonder if I'm doing something
wrong?

--Myron, W0PBV.

The original question said VERTICAL dipole , but you modeled a
HORIZONTAL dipole? Or was one of these just a typo?

FWIW, I modeled your horizontal dipole in EZNEC and came up with
slightly DIFFERENT results:
Resonant frequency about 7.335 Mhz
Resistance about 81 ohms
Max gain about 6.54 dBi at 30 degrees
I am INexperienced in using EZNEC and wonder if I'm doing something
wrong?

--Myron, W0PBV.

No, you are correct. I must have been asleep. Funny that nobody
else noticed my error. The difference in your results are probably
due to the fact that EZNEC does not use the Sommerfeld/Norton
ground model which produces more accurate results when the
radiator is near to the ground.

Frank VE6CB

On Sep 13, 10:42*am, "Frank" wrote:
The original question said VERTICAL dipole , but you modeled a
HORIZONTAL dipole? *Or was one of these just a typo?

FWIW, I modeled your horizontal dipole in EZNEC and came up with
slightly DIFFERENT results:
* Resonant frequency about 7.335 Mhz
* Resistance about 81 ohms
* Max gain about 6.54 dBi at 30 degrees
I am INexperienced in using EZNEC and wonder if I'm doing something
wrong?

--Myron, W0PBV.

No, you are correct. *I must have been asleep. *Funny that nobody
else noticed my error. *The difference in your results are probably
due to the fact that EZNEC does not use the Sommerfeld/Norton
ground model which produces more accurate results when the
radiator is near to the ground.

Frank VE6CB

well done

NOTE: This is a repost from my sent file. It didn't appear
20 hours or so after I sent it. Sorry if it's a dupe to anybody.
---------------------------------------------------------------------
"Art Unwin" wrote in message
news:7ce5bd71-d583-433d-88f0-

snip

The navy would not change to a antenna that was not resonant.

Perhaps you are speaking of another country's Navy with which you are
well-acquainted.

Having been intimately involved with US Navy electronics for over 45 years
(active duty 1962 -1982; civilian support in multiple capacities 1982 -
2007) I can tell you that our Navy has numerous shipboard and
shore-establishment antennas that are not resonant. Since flexibility in
frequency selection confers a tactical advantage, broadbanding is far more
important. Tuners and couplers of several designs allow non-resonant
antennas to work well.

The closest the Navy gets to resonant antennas is in some special
fixed-frequency applications, like IFF. Of course, antennas are sized for
the application and will probably exhibit resonance within their band of
operation, but that's not the design goal.

On Sat, 13 Sep 2008 15:42:00 GMT, "Frank"
wrote:

No, you are correct. I must have been asleep. Funny that nobody
else noticed my error. The difference in your results are probably
due to the fact that EZNEC does not use the Sommerfeld/Norton
ground model which produces more accurate results when the
radiator is near to the ground.

Hi Frank,

It was noticed, but certainly not by Authur. I don't hold out any
hope of ever seeing him do half the work to show numbers to prove his
concept.

However, you are still asleep. EZNEC does offer you the choice of
Sommerfeld/Norton grounds, and you even get to define the
characteristics of that ground. This, too, is something that Authur
has no competence with, or let's just say he has refused to share
actual data there too.

As for the Navy using tilted antennas (suggested by an unnamed
admiral, Authur's usual anonymous authorities).... Well, I have been
invited aboard fighting ships in the last year. I have inspected
their AEGIS radars systems. I have taken pictures of their antennas.
If any one is interested, I could post some at my web site that are
absolutely beyond many correspondent's experience. They are not
tilted (an absurdity) unless a hurricane force wave slapped them into
the hull (not obviously evident by any evidence however).

73's
Richard Clark, KB7QHC

Hi Frank,

It was noticed, but certainly not by Authur. I don't hold out any
hope of ever seeing him do half the work to show numbers to prove his
concept.

However, you are still asleep. EZNEC does offer you the choice of
Sommerfeld/Norton grounds, and you even get to define the
characteristics of that ground. This, too, is something that Authur
has no competence with, or let's just say he has refused to share
actual data there too.

As for the Navy using tilted antennas (suggested by an unnamed
admiral, Authur's usual anonymous authorities).... Well, I have been
invited aboard fighting ships in the last year. I have inspected
their AEGIS radars systems. I have taken pictures of their antennas.
If any one is interested, I could post some at my web site that are
absolutely beyond many correspondent's experience. They are not
tilted (an absurdity) unless a hurricane force wave slapped them into
the hull (not obviously evident by any evidence however).

73's
Richard Clark, KB7QHC

Thanks for the info Richard. Obviously any NEC based program
will have the Sommerfeld/Norton option. As for Navy antennas;
I have seen that they can be tilted, but only so they do not
get shot to pieces by the ships weapons. I too wondered "What
admiral, and in which port".

73, Frank, VE6CB

"Richard Clark" wrote in message
...


As for the Navy using tilted antennas (suggested by an unnamed
admiral, Authur's usual anonymous authorities).... Well, I have been
invited aboard fighting ships in the last year. I have inspected
their AEGIS radars systems. I have taken pictures of their antennas.
If any one is interested, I could post some at my web site that are
absolutely beyond many correspondent's experience. They are not
tilted (an absurdity) unless a hurricane force wave slapped them into
the hull (not obviously evident by any evidence however).

Absurdity or no, a "stealthing" technique for the Arleigh Burke class
of destroyers involves sharply limiting the radar cross-section by not
installing vertical structures, including most, if not all, the antennas.

See this picture, which is typical.

http://en.wikipedia.org/wiki/Image:U...iterranean.jpg

You can clearly see two pairs of tilted HF whips, one pair amidships and
another pair on the stern. This same stealthing technique is being
employed on the new LPD-17 class.

Some Navy antennas are mounted on tilting mechanisms which allow
them to pivot all the way horizontal, so as not to be a hazard to aircraft.
That's different.

"Art Unwin" wrote in message
...
A sloper antenna when resonant produces more gain
than a vertical dipole resonant at the same frequency.
True or false? prove it

Gain in which direction? True AND False - Prove otherwise.

On Sep 13, 9:03*pm, "Hal Rosser" wrote:
"Art Unwin" wrote in message

...

A sloper antenna when resonant produces more gain
than a vertical dipole resonant at the same frequency.
True or false? prove it

Gain in which direction? True AND False - Prove otherwise.

Sometimes you just have to do it for yourself instead of the use of
free speech
where there is no accountability

Art Unwin wrote:

...
Sometimes you just have to do it for yourself instead of the use of
free speech
where there is no accountability

We have a few words to describe such, here in America (well, real
Americans do anyway):

"Sticks and stones may break my bones but words will never hurt me." --
source unknown.

It dates back to about the time of our forefathers drafting of the
constitution, if not well before ...

IMHO, it could not be said better.

Regards,
JS