# [SI-LIST] Re: Amplitude loss ?

• From: rajneesh shukla <rajneeshs123@xxxxxxxxx>
• To: steve weir <weirsi@xxxxxxxxxx>
• Date: Fri, 6 Jan 2012 18:15:33 +0530

```Steve,
There is a law of conservation of energy but no law for conservation of
voltage and If we use ohm's law, voltage drop(loss) occurs only when there
is series impedance in load path. As per ohm law, there won't be any
voltage drop if we connect shunt impedance to load. *I am all confused
because I am not seeing any series impedance in transmission line( when
conductor loss is zero) so where my voltage is dropping ?*

Agree that when ever there is a change in impedance there will be change in
energy dissipation or i should say change in energy reflection or
absorption but *my concern here is amplitude of signal which is voltage(
Energy per unit charge) not total energy.* In free coffee example, I agree
you can't make free cofee as there will be energy loss due to dielectric
loss* but why you think dielectric energy loss mean voltage loss ? *
**
Rajneesh

On Fri, Jan 6, 2012 at 5:04 PM, steve weir <weirsi@xxxxxxxxxx> wrote:

> Dielectric loss does not increase the effective impedance of either the
> near-end or far-end ports.
>
> Steve.
>
>
> On 1/6/2012 3:14 AM, rajneesh shukla wrote:
>
> Thanks Steve but question remains unanswered !!
>
>
>
> I agree there will be a loss in energy due to dielectric loss but I was
> talking about loss in amplitude of signal (voltage) not loss in total
> energy, Energy loss does not always translates into voltage loss, right ?
> Receiver senses voltage( Potential Energy per unit charge) not total energy.
>
>
>
> As per basic circuit theory, If I have a driver that has zero o/p
> impedance is driving a 50 Ohm load and now if I connect 100 Ohm resistance
> across this load, Though there is energy loss due to 100 ohm resistance but
> still my load will see the same voltage, agree ?
>
> No I do not agree.  If you change the port impedance you will change the
> amount of energy absorbed and the amount of energy reflected.
>
>
>
>
> In transmission line, If series loss i.e. conductor loss is zero then I
> don't find the reason of any voltage drop in transmission line coz
> dielectric loss which is shunt loss can only dissipate total energy but
> can't change amplitude(voltage) of signal.
>
> No I do not agree.  If such a thing were true then you could heat your
> top of it.
>
>
>
> Do you find any discrepancy in this analogy ?
>
> Yes:  Conservation of Energy and Ohm's Law.
>
>
>
> On Fri, Jan 6, 2012 at 2:40 PM, steve weir <weirsi@xxxxxxxxxx> wrote:
>
>> Follow the energy.  Achieve enlightenment.  Of the energy that a shunt
>> draws, how much of that energy remains available to the signal?
>>
>> Steve.
>>  On 1/6/2012 12:54 AM, rajneesh shukla wrote:
>> > Experts,
>> > As we know for perfectly matched line insertion loss is due to ohmic&
>> > dielctric losses and due to these losses we see loss in rise/fall time
>> as
>> > well as loss in amplitude of signal.
>> >
>> > My question is what actually affects amplitude loss, is it ohmic loss or
>> > dielectric loss ? My understanding says, it should be ohmic loss as
>> > it comes in series coz dielectric one is shunt loss. If this analogy is
>> > correct then a channel having very low ohmic loss but significant
>> > dielectric loss will have only changes in rise time but minimal
>> amplitude
>> > loss, right ??
>> >
>> > Rajneesh
>> >
>> >
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>>
>> --
>> Steve Weir
>> IPBLOX, LLC
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>
>
> --
> Steve Weir
> IPBLOX, LLC
> 150 N. Center St. #211
> Reno, NV  89501 www.ipblox.com
>
> (866) 675-4630 Toll-free
> (707) 780-1951 Fax
>
> This e-mail may contain confidential material.
> If you are not the intended recipient, please destroy all records
> and notify the sender.
>
>

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