Parallel coax
 

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.

Parallel coax
 

"Ian Jackson" wrote in message
...
Which is greater - 10db or -30db?

In voltage ratios, they are 1/3 and 1/30 respectively, and in power
ratios, 1/10 and 1/000 respectively. But if you lost 30dB down your coax,
you'd be losing 20dB MORE than if you were only losing 10dB. But surely
even you wouldn't say "My coax has a loss of minus 30dB"? [Or would you?!]

dB without a refferance to something like voltage or power is not much if
any use.

Parallel coax
 

On 9/29/2015 12:45 PM, Ralph Mowery wrote:
"Ian Jackson" wrote in message
...
Which is greater - 10db or -30db?

In voltage ratios, they are 1/3 and 1/30 respectively, and in power
ratios, 1/10 and 1/000 respectively. But if you lost 30dB down your coax,
you'd be losing 20dB MORE than if you were only losing 10dB. But surely
even you wouldn't say "My coax has a loss of minus 30dB"? [Or would you?!]

dB without a refferance to something like voltage or power is not much if
any use.

Really? Not all measurements are absolute. The return loss we have
been discussing is a perfect example. One power level vs. another. No
need to consider the units as they factor out.

--

Rick

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 :)

Parallel coax
 

"rickman" wrote in message ...

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:

snip
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."

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?

Well, it is exactly what I thought I learned on the subject. :)

Parallel coax
 

On 9/29/2015 2:10 PM, Wayne wrote:


"rickman" wrote in message ...
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:

snip
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."

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?

Well, it is exactly what I thought I learned on the subject. :)

To be honest, it seems logical that the power in should be the reference
and the reflected power should be the property being measured which is
what Jerry is saying. But clearly for this particular term "return
loss" this is not the case.

Does it seem intuitively correct that "return loss" should be a higher
number when the reflection is smaller?

--

Rick

Parallel coax
 

"rickman" wrote in message ...

On 9/29/2015 2:10 PM, Wayne wrote:


"rickman" wrote in message ...
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:

snip
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."

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?

Well, it is exactly what I thought I learned on the subject. :)

# To be honest, it seems logical that the power in should be the reference
# and the reflected power should be the property being measured which is
# what Jerry is saying. But clearly for this particular term "return
# loss" this is not the case.

# Does it seem intuitively correct that "return loss" should be a higher
# number when the reflection is smaller?

There seems to be a case for saying it either way.
My exposure to RL was "on the job" when playing with antennas and a network
analyzer.
We always used positive numbers and viewed RL as the difference in dB
between the forward and reflected power.

Actually, RL was something in the network analyzer data file and printout.
We pretty much ignored it and looked at S parameters and SWR.

Parallel coax
 

On 9/29/2015 1:45 PM, Wayne wrote:


"rickman" wrote in message ...

On 9/29/2015 2:10 PM, Wayne wrote:


"rickman" wrote in message ...
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:

snip
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."

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?

Well, it is exactly what I thought I learned on the subject. :)

# To be honest, it seems logical that the power in should be the reference
# and the reflected power should be the property being measured which is
# what Jerry is saying. But clearly for this particular term "return
# loss" this is not the case.

# Does it seem intuitively correct that "return loss" should be a higher
# number when the reflection is smaller?

Yes. It is not necessarily a loss. Consider a loss-less line and a
perfect source. You still have a return loss, but there are no losses in
the system.

There seems to be a case for saying it either way.
My exposure to RL was "on the job" when playing with antennas and a
network analyzer.
We always used positive numbers and viewed RL as the difference in dB
between the forward and reflected power.

That makes perfect sense. You could never have a negative dB.

Actually, RL was something in the network analyzer data file and
printout. We pretty much ignored it and looked at S parameters and SWR.

Parallel coax
 

In message , rickman
writes



Does it seem intuitively correct that "return loss" should be a higher
number when the reflection is smaller?

After a few milliseconds of serious consideration, "Yes"!
--
Ian

Parallel coax
 

On 9/27/2015 1:42 PM, John S wrote:
On 9/27/2015 1:20 PM, Wayne wrote:


"rickman" wrote in message ...

On 9/27/2015 10:41 AM, kg7fu wrote:

Matching the antenna won't make the Return Loss go away but it will
make
the transmitter happy.

Can you explain this? I thought matching the antenna would *exactly*
make the return loss go away because it would eliminate the mismatch.

Not wanting to put words in his mouth....
I read that to mean that the high SWR between the ATU and the antenna
would remain, but the transmitter would be happy with the SWR on the
transmitter/ATU coax.


Rick is correct. If the antenna (load) is matched to the line, there is
no return loss, hence no SWR. The ATU will be adjusted (hopefully) to
make the transmitter operate properly with the impedance as seen at the
transmitter end of the line.

I apologize. My statement that "there is no return loss" above is
technically incorrect. The return loss with matched conditions is
maximum. It will peg your meter.