My EM guys, Physics types, [from my working days] indicated that the
three dielectric interfaces, adhesive to glass to adhesive, all with
different dielectric coefficients create reflections at the boundaries.

There are four. You couldn't really have an odd number..

Metal-adhesive, adhesive-glass, glass-adhesive, adhesive-metal.

Then there's the tuner box and all that on the feedline to consider.
Not surprising that there's some significant loss in the process.

My EM guys, Physics types, [from my working days] indicated that the
three dielectric interfaces, adhesive to glass to adhesive, all with
different dielectric coefficients create reflections at the boundaries.

There are four. You couldn't really have an odd number..

Metal-adhesive, adhesive-glass, glass-adhesive, adhesive-metal.

Then there's the tuner box and all that on the feedline to consider.
Not surprising that there's some significant loss in the process.

On Tue, 06 Apr 2004 11:48:53 GMT, Dave Shrader
wrote:

Richard Clark wrote:

On Mon, 05 Apr 2004 23:54:51 GMT, Dave Shrader
wrote:

Theoretically, the loss is about 0.5 to 1.0 dB for clear glass.


Hi Dave,

What's the theory?

73's
Richard Clark, KB7QHC

My EM guys, Physics types, [from my working days] indicated that the
three dielectric interfaces, adhesive to glass to adhesive, all with
different dielectric coefficients create reflections at the boundaries.

Hi Dave,

Poor theory. Reflection is not loss. There are reflections galore on
a radiator that supports the Standing Wave and yet with a large enough
metal surface it is nearly 100% radiative.

As for this boundaries explanation, those "Physics types" clearly did
not have any working knowledge (experience) - about as useful as
Cecil's poorly offered Light analogies suffering from the same lack.
I further note that none of this indicts clear glass (which may have
been a semantic issue) to the tune of nearly 1dB.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
Cecil's poorly offered Light analogies suffering from the same lack.

That's pretty funny, Richard, since you are agreeing with me 100%
in this posting. Glass that allows glare loses some light in the
rearward direction (reflections). Glass that doesn't allow glare
ensures that all the light reaches the object. Unmatched RF systems
can allow reflected power to be lost from the load. Matched RF
systems ensure that all the power reaches the load (minus line
losses).

You have never said anything worthwhile that technically disagrees
with me. Your only objections are to my style (witness the above).
--
73, Cecil, W5DXP



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Richard Clark wrote,

My EM guys, Physics types, [from my working days] indicated that the
three dielectric interfaces, adhesive to glass to adhesive, all with
different dielectric coefficients create reflections at the boundaries.

Hi Dave,

Poor theory. Reflection is not loss. There are reflections galore on
a radiator that supports the Standing Wave and yet with a large enough
metal surface it is nearly 100% radiative.

As for this boundaries explanation, those "Physics types" clearly did
not have any working knowledge (experience) - about as useful as
Cecil's poorly offered Light analogies suffering from the same lack.
I further note that none of this indicts clear glass (which may have
been a semantic issue) to the tune of nearly 1dB.

73's
Richard Clark, KB7QHC


Hi Richard,
absent any numbers on the loss tangent of automobile window
glass at the frequency in question, any estimate of loss is just a guess.
73,
Tom Donaly, KA6RUH

Wasn't it James Thurber who said, "When someone says 'theoretically,' he
means 'not actually.'"?

73
Bob AD3K

Richard Clark wrote:

On Mon, 05 Apr 2004 23:54:51 GMT, Dave Shrader
wrote:

Theoretically, the loss is about 0.5 to 1.0 dB for clear glass.


Hi Dave,

What's the theory?

73's
Richard Clark, KB7QHC

--
Robert L. Spooner
Registered Professional Engineer
Associate Research Engineer
Intelligent Control Systems Department

Applied Research Laboratory Phone: (814) 863-4120
The Pennsylvania State University FAX: (814) 863-7841
P. O. Box 30
State College, PA 16804-0030

Robert Spooner wrote:
Wasn't it James Thurber who said, "When someone says 'theoretically,' he
means 'not actually.'"?

73
Bob AD3K

When I use 'theory' or 'theoretically', I'm using it in the engineering
context of Physics and Mathematics. Meaning the mathematical solution
of the LAWs of Physics are applicable.

There are other understandings of theory: such as the district
attorney's theory behind a crime; or, in science terms the next step
beyond 'hypothesis'; or, the step below 'law of nature'.

The theory is understanding 'WHY' things are actually, to quote your
word above. Knowledge, in engineering and science, is incomplete without
the THEORY of operation or Physics.

So, I reject your hypothesis regarding Thurber's statement. It is
inconsistent with science/engineering/physics.

On Tue, 06 Apr 2004 15:02:45 GMT, Dave Shrader
wrote:

Robert Spooner wrote:
Wasn't it James Thurber who said, "When someone says 'theoretically,' he
means 'not actually.'"?

73
Bob AD3K

When I use 'theory' or 'theoretically', I'm using it in the engineering
context of Physics and Mathematics. Meaning the mathematical solution
of the LAWs of Physics are applicable.

Hi Dave,

This is a catch-all application of "theory." The solutions are
always applicable and the casual employment of the phrase "in theory"
is thus rendered gratuitous (or rhetorical chaff) - hence the
attachment of Thurber's observation that is a sardonic reference to
the lack of any actuality. You have confirmed that his artistic prose
has as much validity as Physics.

73's
Richard Clark, KB7QHC

But it is not clear glass, it is tinted.

And, yes, I meant the window mounting not the cellular antenna (I asked that
in a seperate post).

Do you have a Taurus wagon? I was hoping to find someone here who actually
tried a glass mount on a Taurus. [I find it amusing how many people respond
to a post without reading it. Someone actually suggested putting a mag
mount on the trunk!]

Jim
N8EE
"Dave Shrader" wrote in message
news:elmcc.75941$gA5.905305@attbi_s03...
JLB wrote:

I have a 2000 model year Ford Taurus wagon, and am thinking about
mounting a
through-glass antenna on one of the back side windows. Yes, I know---a
roof
mount would work better, but I would have to get a hole punch and a
divorce
lawyer to do it ;-)

Does anyone have any practical experience with this set up? Does the
window
tinting cause any problems on 146 MHz or 440 MHz?

Possibly

There is a completely dark (opaque) band around the edge of the window.
Should this be avoided?

YES


I have seen Taurus wagons with cell phone antennas on the back side
windows,
and was wondering how it worked on the ham bands.

Cell phone antennas perform poorly on 2 & 440 grin. I presume you
mean the mounting not the antenna. Through the glass should be fine.

I use a Larsen Through the Glass and there is no noticeable loss of
signal. Theoretically, the loss is about 0.5 to 1.0 dB for clear glass.

Deacon Dave, W1MCE


Jim
N8EE

It seems like a thousand years ago when a big discussion of glass mount
antennas took place on INFO-HAMS.

(Anyone remember INFO-HAMS?)

My poor memory recalls that there was not much said in favor of glass mount
antennas and a lot said against them. Most of the discussion was regarding 2-m
antennas.

I think the mag mount antenna is a great invention and that's all I use for 2
and 0.7.

When traveling I put the antenna on top of the car. Around town I mount on
truck lid.

73 de Jack, K9CUN