Hi Don,
Sorry to hear about your tool vendor :-)
You are correct, the modal normalization is complicated subject with
possible consequences. It basically defines the current/voltage/waves and
characteristic impedance (or impedance in case of a resonator) for the
final multiport model. Now, imagine that you have two models with the
different normalization (one is power-current and another is power-voltage
or voltage-current normalization for instance) - is it possible to connect
them? What would be the consequences?
It was a subject of intense discussion in microwave community many years ago
- here are some papers (not all) on the subject
1) R.H. Jansen, N.H.L. Koster, New aspects concerning the definition of
microstrip characteristic impedance as a function of frequency. - IEEE MTT-S
Int. Microwave Symp. Digest, 1982, p.305-307.
2) J.C. Rautio, A new definition of characteristic impedance, IEEE MTT-S
Int. Microwave Symp. Digest, 1991, p.761-764.
3) L. Zhu, K. Wu, Revisiting characteristic impedance and its definition of
microstrip line with a self-calibrated 3-D MoM scheme, IEEE Microwave and
Guided Wave Letters, v. 8, 1998, N2, p.87-89.
4) J.C. Rautio Comments on Revisiting characteristic impedance and its
definition of microstrip line with a self-calibrated 3-D MoM scheme, and L.
Zhu, K. Wu, Author's reply, IEEE Trans., v. MTT-47, 1999, N1, p.115-119.
All modal normalizations are approximations and it does not matter as long
as all models in the channel have the same definition of the characteristic
impedance.
Best regards,
Yuriy
Yuriy Shlepnev, Ph.D.
President, Simberian Inc.
2629 Townsgate Rd., Suite #235, Westlake Village, CA 91361, USA
Office +1-702-876-2882; Fax +1-702-482-7903
Cell +1-206-409-2368; Virtual +1-408-627-7706
Skype: shlepnev
www.simberian.com
Simbeor - Accurate, Productive and Cost-Effective Electromagnetic Signal
Integrity Software
2010 and 2011 DesignVision Award Winner, 2015 Best In Design&Test Finalist
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Don Pakbaz
Sent: Tuesday, June 7, 2016 10:36 AM
To: shlepnev@xxxxxxxxxxxxx
Cc: SI
Subject: [SI-LIST] Re: modal voltage and modal current with normalized
energy.
Hi Yuriy;
Thanks for your explanation...It helped a great deal! I been asking the tool
vendor and have a ticket open on this topic with them but they cannot
explain it well. Their AE so far struggling back and forth with their R&D.
It is a a difficult and convoluted concept to understand but with references
that you given maybe I will finally grasp it. Thanks again
On Tue, Jun 7, 2016 at 11:05 AM, Yuriy Shlepnev <shlepnev@xxxxxxxxxxxxx>
wrote:
Hi Don,functions instead of just sin and cosine functions.
You have to ask the CAD vendor on the normalization definition used in
your particular case.
In general, it is all about mapping of Maxwell's equations solution
into a microwave network. Electric and magnetic fields are mapped into
voltages or waves and currents to reduce the problem to a multiport
network or equivalent circuit.
Solutions of the Maxwell's equations for resonators and waveguiding
structures are sets of resonance or propagating/evanescent modes.
Modal electric and magnetic fields of a resonator can be used as the
basis functions to define voltage, current and equivalent circuit of
the resonator. Modal fields of a waveguiding structures (PCB or
packaging
interconnects) can be used as the basis functions to reduce problem to
Telegrapher's equations and use transmission line theory to solve
them. It is called modal decomposition. Such reduction is exact if
voltage and current are used as the expansion coefficients with the
electromagnetic modes directly. Though, depending on the
normalization, you may end up with different values of the modal
voltage, current, and characteristic impedance. The reduction is an
approximation if voltages and currents are defined as in the circuit
theory (current-voltage, current-power or voltage-power for quasi-TEM
solutions for instance). Voltages and currents in the modal space are
just coefficients in the Fourier expansion that uses modes as the basis
Models constructed in this way can be connected only with the modelstool.
with exactly the same definition of voltages, currents or waves. The
end result (multiport parameters of a network) should be independent
of the internal normalization and presented in the measurable
variables (currents and voltages or waves). Electromagnetic fields
computed from the voltages and currents defined at the ports are also
unique and should be independent of the internal normalization used in a
Here are some classical books on the subject:
N. Markuvitz, Waveguide handbook, 1951 R. Harrington, Time harmonic
electromagnetic fields, 1961 R.E. Collin, Field theory of guided
waves, 1991 F. Olyslager, Electromagnetic waveguides and transmission
lines, 1999
Best regards,
Yuriy
Yuriy Shlepnev, Ph.D.
President, Simberian Inc.
2629 Townsgate Rd., Suite #235, Westlake Village, CA 91361, USA Office
+1-702-876-2882; Fax +1-702-482-7903 Cell +1-206-409-2368; Virtual
+1-408-627-7706
Skype: shlepnev
www.simberian.com
Simbeor - Accurate, Productive and Cost-Effective Electromagnetic
Signal Integrity Software
2010 and 2011 DesignVision Award Winner, 2015 Best In Design&Test
Finalist
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]
On
Behalf Of Don Pakbaz
Sent: Monday, June 6, 2016 7:16 AM
To: SI
Subject: [SI-LIST] modal voltage and modal current with normalized energy.
Dear Experts;
Is there a Literature/Documentation that explains what the "modal
voltage and modal current with normalized energy." is?
I am running to this issue on some of the CAD vendor tools that for
example trying to explain resonance mode voltage. They explain as:
"current are modal voltage and modal current with normalized energy.
To put it simple, if the total energy of the mode is normalized, the
modal voltage and modal current distribution is determined.
There is a domain and a resonant mode in this domain. If you do
mode_V*mode_I integration over the whole domain, you get the energy of
this mode. If this energy is normalized to 1, then you have the mode_v
distribution."
I am not exactly sure what this means! Do I need to go get a PHD in EM
to understand this concept? Thank you kindly for any help or comments
you can provide...
--
Regards;
Don Pakbaz
Global Foundries
1000 River Rd, M/S 863H
Essex Jct, VT 05452
Email: don.pakbaz@xxxxxxxxxxxxxxxxxxx <pakbazf@xxxxxxxxxx>
Voice: (802) 769-5638 Tieline: 446-5638
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