In message , Jerry Stuckle
writes
On 9/29/2015 3:47 AM, Ian Jackson wrote:
In message , Jerry Stuckle
writes
On 9/28/2015 7:12 PM, John S wrote:
On 9/28/2015 1:51 PM, Jerry Stuckle wrote:
On 9/28/2015 1:42 PM, rickman wrote:





You said return loss increases with lower SWR. It does not.


It does.

Sorry, a lower SWR does not increase the amount of loss.

Of course it doesn't. No one said it did. It does the opposite, ie a
lower SWR gives less loss on the feeder.

Please cite a reliable reference that says it does. Even the table Rick
cited shows a negative value for return SWR.

What is this 'Return SWR'? I'm not familiar with it.


Sorry, writing too quickly. I meant return loss.

Do you mean Return Loss Ratio (RLR)? This is a simple, easily
measurable, and meaningful statement of how strong the returning
reflected signal is compared with the outgoing forward signal.

The reflected signal is a weaker version of the forward signal. It's
expressed as a loss, an attenuation, or relatively how much down the
level of the reflection is. You can express this as a numerical ratio -
the reflection coefficient (rho) - or (as often more convenient) rho in dB.

As others have suggested, what is apparently a negative sign in the
chart is presumably more artistic licence than scientific accuracy. If
you lose $10, you don't say that you lost 'minus $10'. Similarly, when
you lose 10dB of signal, you don't say you lost 'minus 10dB'.

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?!]
--
Ian