Reg Edwards wrote:
. . .
I've often thought of modelling a mobile loaded whip in a computer
program. Input data would include body dimensions and height above
ground. With a lot of patience you could do it with an EZNEC type of
program.

Many people have done it with EZNEC. At HF, all that's necessary is a
pretty crude outline, except in the close vicinity of the antenna where
currents can change more rapidly. At VHF and above a much finer wire
grid model is necessary. But as others have pointed out, a lot of modern
cars aren't covered by a solid metal shell. So it might be difficult for
these cars to figure out just what external and internal metallic parts
will be carrying the current and therefore need to be included in the model.

Roy Lewallen, W7EL

Sorry, I don't know any more about the antenna than you do, and
hopefully less (since it sounds like you're intending to make use of
it). I suggest you contact the vendor for application help. Most
manufacturers are glad to provide it.

Roy Lewallen, W7EL

redhat wrote:
Thanks for your reply. what about this patch antenna
http://rocky.digikey.com/WebLib/Toko...K1575MS50T.pdf
it has a feed pin at the center, the ground is the whole area around
the pin , they say it has an adhesive tape for ease in mounting to the
ground plane , is this adhesive tape a good conductor so that it
connects the antenna ground to the circuit's ground or what? so,in the
pcb design should i make a rectangular copper area under this antenna
connected to the ground?
Regards,
Redhat

Cecil Moore wrote:
Reg Edwards wrote:

With mobile verticals what is ALWAYS forgotten about is that the car
body is just as much a part of the radiating system as the antenna.


I've always considered the vehicle body as a funny looking
large diameter elevated radial. :-)

That (a single fat radial) might be a reasonable model if the antenna is
mounted at one end of the vehicle. If it's at the center of the top, the
antenna is more like an asymmetrical dipole, with the "antenna" being
one half and the vehicle being a much fatter lower half. In that case
the car will produce a substantial vertically polarized field -- perhaps
more than the "antenna".

Roy Lewallen, W7EL

Roy Lewallen wrote:
That (a single fat radial) might be a reasonable model if the antenna is
mounted at one end of the vehicle.

My screwdriver is mounted in my GMC pickup trailer hitch hole.
--
73, Cecil http://www.qsl.net/w5dxp

----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

In article ,
Wes Stewart wrote:

On Wed, 08 Jun 2005 17:57:21 -0000, (Dave Platt)
wrote:


Similar issues are likely to exist in recent-model cars which have a
lot of fiberglass or other composite-plastic panels and structure.

Back in the good old days, I was the proud owner of a 1956 Corvette,
one of only 3467 built and along with the '57s, the prettiest ones
ever buit. (damn I wish I had that car back). As are all Corvettes,
it was fiberglass.

all corvettes were not fiberglass!





The soft top was stored under a flip up hatch behind the seats and
there were two toggle clamps that secured the rear of the top when it
was up. These penetrated the hatch cover so that it was possible to
snake a vertical whip through them. I used a 17" aluminum
transcription disk (common in broadcast stations of the day) with the
coating stripped off for a ground plane under the hatch.

Best DX using a Heathkit "Twoer" was from the driveway of a friend in
Tempe, AZ back to another friend in Tucson; about 100 miles.

This wasn't long after QST magazine had breathlessly reported that the
"difficult path" between Tucson and Phoenix had been bridged.

On Fri, 10 Jun 2005 11:19:29 GMT, ml wrote:

In article ,
Wes Stewart wrote:

On Wed, 08 Jun 2005 17:57:21 -0000, (Dave Platt)
wrote:


Similar issues are likely to exist in recent-model cars which have a
lot of fiberglass or other composite-plastic panels and structure.

Back in the good old days, I was the proud owner of a 1956 Corvette,
one of only 3467 built and along with the '57s, the prettiest ones
ever buit. (damn I wish I had that car back). As are all Corvettes,
it was fiberglass.

all corvettes were not fiberglass!
^^^^^^^^^^^^^^^^^^^^^^^^^

OK, I'm calling bull**** on this one. What production Corvette was
not GRP (glass reinforced polyester) or other non-metallic composite?

R






The soft top was stored under a flip up hatch behind the seats and
there were two toggle clamps that secured the rear of the top when it
was up. These penetrated the hatch cover so that it was possible to
snake a vertical whip through them. I used a 17" aluminum
transcription disk (common in broadcast stations of the day) with the
coating stripped off for a ground plane under the hatch.

Best DX using a Heathkit "Twoer" was from the driveway of a friend in
Tempe, AZ back to another friend in Tucson; about 100 miles.

This wasn't long after QST magazine had breathlessly reported that the
"difficult path" between Tucson and Phoenix had been bridged.

Russ wrote:

OK, I'm calling bull**** on this one. What production Corvette was
not GRP (glass reinforced polyester) or other non-metallic composite?


I know very little about this, but a few months ago I was fascinated by
a half hour program about the history of the Corvette on public TV.
(It's one of a series.) Turns out that the first couple of 'vettes
weren't muscle cars at all, but gutless wonders with a small engine and
two-speed automatic transmission -- it took a while to evolve. I don't
recall for sure, but think it's likely those were metal.

Roy Lewallen, W7EL

Roy:

You are right on target, I would have to ask my dad, but back around
1960 he had a 1956 vet (if I remember the year correctly--it was a 4
speed--again, if I remember correctly--that is really pressing my memory
though--could easily be wrong)... it was an all aluminum body (sure
about that), had a big engine, stick shift, and he never got out of
second gear in town... however, it did NOT seem gutless to me... nor him
as I remember it... he could have had a larger engine placed it it
though... he had it for many years... sold it in the 70's for way more
than he bought it for!!! ... he claims it was the only car he ever got
a ticket in, and more than one...

John

"Roy Lewallen" wrote in message
...
Russ wrote:

OK, I'm calling bull**** on this one. What production Corvette was
not GRP (glass reinforced polyester) or other non-metallic composite?


I know very little about this, but a few months ago I was fascinated
by a half hour program about the history of the Corvette on public TV.
(It's one of a series.) Turns out that the first couple of 'vettes
weren't muscle cars at all, but gutless wonders with a small engine
and two-speed automatic transmission -- it took a while to evolve. I
don't recall for sure, but think it's likely those were metal.

Roy Lewallen, W7EL

Roy Lewallen wrote:
Turns out that the first couple of 'vettes
weren't muscle cars at all, but gutless wonders with a small engine and
two-speed automatic transmission -- it took a while to evolve. I don't
recall for sure, but think it's likely those were metal.

Don't know about the body but it had virtually the same 6 cyl
engine and transmission as my uncle's 1955 Chevy Bel Aire.
Chevy introduced the V8 (350 in^3?) in 1956 and that's when
it went into the Corvette and into all those Chevys that broke
all the records that year.
--
73, Cecil http://www.qsl.net/w5dxp

----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

John Smith wrote:
You are right on target, I would have to ask my dad, but back around
1960 he had a 1956 vet ... however, it did NOT seem gutless to me...

The Corvette was introduced in 1955 with Chevy's old straight
six engine. I remember it in a Mike Hammer movie, "Kiss Me Deadly".
The 1956 models got that first short stroke V8 which was the
grandfather of the engine in my daughter's 2003 Chevy Tahoe.
--
73, Cecil http://www.qsl.net/w5dxp

----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----