[SI-LIST] Re: S-parameter Bisection
- From: Ihsan Erdin <erdinih@xxxxxxxxx>
- To: "Kevin G. Rhoads" <kgrhoads@xxxxxxxxxxxx>
- Date: Wed, 11 Nov 2009 17:08:56 -0500
In microwave applications, i.e. when dealing with waveguides, the
voltage and current will be path dependent (not unique) on the
cross-section of the guide for high order modes. In this case the y
(and abcd) parameters may not even be defined and one would have no
option but resorting to the t-parameters in order to cascade the
structures. However, for all SI applications that I know, the
transmission line theory (the lowest waveguide mode) must prevail
where the lines are connected to driver and receiver circuitry. In
this case the voltage and current at the line ends will be uniquely
defined and preferring abcd parameters over t-parameters or vice-versa
will not really matter from a practical point of view.
The truth is any circuit simulator based on modified nodal admittance
(MNA) matrix will eventually convert the s-parameters into
y-parameters. However, if switching between the circuit parameters is
required more than once before putting the whole structure into the
MNA matrix the use of t-parameters still seems more advantageous since
they are of the same genre as the s-parameters and one doesn't have to
worry about the reference impedance in the conversion. It may be a
minor point but worth consideration...
Regards,
Ihsan
On Wed, Nov 11, 2009 at 3:39 PM, Kevin G. Rhoads <kgrhoads@xxxxxxxxxxxx> wrote:
>>I especially emphasized the transmission coefficients (T-parameters)
>>instead of notorious ABCD parameters because T-parameters are
>>expressed in terms of reflected and transmitted power at the ports
>>just like s-parameters while the ABCD parameters are in terms of
>>voltage and current.
>
> I'm curious about this comment, could you amplify? Please.
>
> Are you recommending against ABCD matrices in the intermediate step
> because the final result will suffer or be less accurate? Obviously,
> if calculations could be done with infinite precision, it shouldn't
> matter -- so why does it matter here?
>
> Sincerely
> Kevin
>
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
