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.

On Sat, 13 Sep 2008 23:53:32 -0700, "Sal M. Onella"
wrote:

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.

I would say that they are in the typical sea-swept configuration, not
found on the Fletcher Class Destroyers of my duty, but mixed in with
the designs of, say, the later Barry:
http://en.wikipedia.org/wiki/Image:USS_Barry.jpg
Where you can nearly see two tilted HF whips, one amidships and
another behind the aft stack (actually both are behind their
respective stacks, as are the stacks sea-swept). The design of
reduced right angles is a staple in the "tripod masts." Obviously,
these 50 year old features were in place for reasons of their own that
were separate from radar silhouette considerations. Further, the
largest silhouette would be broadsides where the whips in ALL these
pictures are at 90 degrees to the beam.

I would also note that the Zumwalt Destroyer Class (as represented in
graphics) lacks any vertical whip antennas at any angle.

However, returning to my own recent shipboard experience and antennas
there, I will later today post a link to a dozen or so pictures. It
will include shots of Guss' Loops. I dare say several of these
pictures will provoke much head scratching (but only to those few
actually interested in antennas here in this forum).

73's
Richard Clark, KB7QHC