[SI-LIST] Re: Amplitude loss ?
- From: rajneesh shukla <rajneeshs123@xxxxxxxxx>
- To: steve weir <weirsi@xxxxxxxxxx>
- Date: Fri, 6 Jan 2012 19:07:11 +0530
Thanks steve !!
I am much clear now with your explanation this time.
Rajneesh
On Fri, Jan 6, 2012 at 6:35 PM, steve weir <weirsi@xxxxxxxxxx> wrote:
> For an electrically long, matched transmission line, the source is
> isolated from distant loads, including shunt losses. The source does not
> pump more power into the line as we increase those losses. Less power
> reaches the far end. Because we stipulated a matched channel, the far end
> impedance is unchanged. Less power at a constant real impedance translates
> to less voltage.
>
> Steve.
>
> On 1/6/2012 4:45 AM, rajneesh shukla wrote:
>
> 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
>> coffee for free by making a long transmission line and setting your cup on
>> 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
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>>
>>
>> --
>> Steve Weir
>> IPBLOX, LLC
>> 150 N. Center St. #211
>> Reno, NV 89501 www.ipblox.com
>>
>> (775) 299-4236 Business
>> (866) 675-4630 Toll-free
>> (707) 780-1951 Fax
>>
>> All contents Copyright (c)2012 IPBLOX, LLC. All Rights Reserved.
>> This e-mail may contain confidential material.
>> If you are not the intended recipient, please destroy all records
>> and notify the sender.
>>
>>
>
>
> --
> Steve Weir
> IPBLOX, LLC
> 150 N. Center St. #211
> Reno, NV 89501 www.ipblox.com
>
> (775) 299-4236 Business
> (866) 675-4630 Toll-free
> (707) 780-1951 Fax
>
> All contents Copyright (c)2012 IPBLOX, LLC. All Rights Reserved.
> 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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