Thread: Parallel coax
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Old September 29th 15, 07:01 PM posted to rec.radio.amateur.antenna
Wayne Wayne is offline
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Default Parallel coax



"John S" wrote in message ...

On 9/29/2015 10:32 AM, rickman wrote:
On 9/29/2015 9:22 AM, Jerry Stuckle wrote:
On 9/29/2015 12:55 AM, rickman wrote:
On 9/28/2015 8:56 PM, Jerry Stuckle wrote:
On 9/28/2015 8:09 PM, rickman wrote:
On 9/28/2015 7:55 PM, Jerry Stuckle wrote:
On 9/28/2015 5:18 PM, rickman wrote:
On 9/28/2015 4:34 PM, Jerry Stuckle wrote:

I'm not interested. I know what it says. Guess I should have
kept up
my IEEE membership, but it just wasn't worth it.

So share with the rest of us. What does it say?


Exactly what your table showed. But you mentioned the resource, not
me.
You pay for it or you've just once again you're full of it.

You said you *know* what the IEEE article says. Why not share with
us?


You want it - you pay for it. Or once again you prove you're full
of it.

No, I have not read the article. But I understand the physics and math
behind it - unlike you. Someone who thinks magnitude without vector
(direction) is valid! ROFLMAO!

Ok, so you mispoke when you said, "I know what it says."



No, I didn't. I didn't say I read it. I said I know what it says. And
I do from other IEEE peer-reviewed articles. I don't need to read it to
find out it agrees with other documentation. And if it didn't, it
wouldn't have gotten published.

You have said repeatedly that the return loss should be calculated by
using the power in as the reference and the reflected power as the thing
being measured which results in a negative log. I am pretty sure the
paper says this is not the correct way to calculate it and many people
are making a mistake doing it this way.


So you've read other IEEE documentation which supports what you say?

I'll see if I can get my hands on the paper. I'm not going to pay for
it. If I thought it would get you to admit you were mistaken, I'd pay
the $100. But I'm sure you will find a way to berate the authors or
twist their logic and I'm not will to pay $100 for that.

So stand by. Someone may be getting it for me.


I really don't give a damn. You would argue the sun rises in the west.


I have a copy of the paper.

Trevor Bird
Editor-in-ehief,Engineering
IEEE Transactions on Antennas and Propagation
CSIRO leT Centre, PO Box 76
Epping, NSW 1710, Australia
Tel: +61 2 9372 4289
Fax: +61 2 9372 4446
E-mail:

Definition and Misuse of Return Loss
Trevor S. Bird

Here is the equation from the article

Pin
RL = 10 log,10 ( ---- ) dB, (1)
Pref

The author explicitly states the resulting value will be positive when
Pin is greater than Pref. He goes on to say, "That is, return loss is
the negative of the reflection coefficient expressed in decibels."


Since the reflection coefficient is never greater than 1, its value is
negative. It follows that the return loss is positive.

He goes on to quote from the "IEEE Standard Dictionary of Electrical
and Electronic Terms, Fourth Edition".

(1 ) (data transmission) (A) At a discontinuity in a
transmission system the difference between the power
incident upon the discontinuity. (B) The ratio in deci-
bels of the power incident upon the discontinuity to the
power reflected from the discontinuity. Note: This ratio
is also the square of the reciprocal to the magnitude of
the reflection coefficient. (C) More broadly, the return
loss is a measure of the dissimilarity between two
impedances, being equal to the number of decibels that
corresponds to the scalar value of the reciprocal of the
reflection coefficient, and hence being expressed by the
following formula:

|Z1 + Z2|
20 log,10 |-------| decibel
|Z1 - Z2|

where Z1 and Z2 = the two impedances.

(2) (or gain) (waveguide). The ratio of incident to
reflected power at a reference plane of a network.


So is this what you "knew" the paper said? Seems to be the opposite of
what you have been promoting.

Anyone feel this paper is incorrect?


# Good find Rick. That should put it to bed.

.....LOL