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Home > Archive > Electrical Engineering > February 2007 > A good Smith Chart program
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A good Smith Chart program
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| Does anyone have a good Smith Chart program? I saw a few Java based on the
net and one I downloaded, however, there must better ones out there.
Thanks
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| Salmon Egg 2007-02-10, 9:25 pm |
| On 2/10/07 1:51 PM, in article f_idnWNzA5TBo1PYnZ2dnUVZ_qOpnZ2d@comcast.com,
"Peter" <private@private.com> wrote:
> Does anyone have a good Smith Chart program? I saw a few Java based on the
> net and one I downloaded, however, there must better ones out there.
>
>
> Thanks
What are you trying to do? I have gotten much use of the Smith chart
primarily for use with optical thin films. I use the chart as a conceptual
tool, but when I get down to serious work I use two by two matrices with
complex components. I think that there use was pioneered by Ernst Guillemin
and others in the 1930;s and 1940's. Sometimes they are called ABCD
matrices.
Bill
-- Fermez le Bush--about two years to go.
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| VWWall 2007-02-11, 3:25 am |
| Salmon Egg wrote:
>
> What are you trying to do? I have gotten much use of the Smith chart
> primarily for use with optical thin films. I use the chart as a conceptual
> tool, but when I get down to serious work I use two by two matrices with
> complex components. I think that there use was pioneered by Ernst Guillemin
> and others in the 1930;s and 1940's. Sometimes they are called ABCD
> matrices.
Do you know of any program using ABCD matrices with complex elements?
I've used APL in the past, but it's pretty complicated for use on a PC.
I wrote a paper back in 1953, on transistor analysis using ABCD
matrices. I never found an easy way to do the calculations required.
With programs like SPICE, other methods are probably not very useful.
--
Virg Wall, P.E.
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"Peter" <private@private.com> wrote in message
news:f_idnWNzA5TBo1PYnZ2dnUVZ_qOpnZ2d@comcast.com...
> Does anyone have a good Smith Chart program? I saw a few Java based on the
> net and one I downloaded, however, there must better ones out there.
>
>
> Thanks
try "Smith" at http://www.fritz.dellsperger.net/downloads.htm
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| "Tony" <GLK@London.Calling> wrote in news:eqm8it$3o1$1@aioe.org:
>
> "Peter" <private@private.com> wrote in message
> news:f_idnWNzA5TBo1PYnZ2dnUVZ_qOpnZ2d@comcast.com...
>
>
> try "Smith" at http://www.fritz.dellsperger.net/downloads.htm
>
>
>
Doesn't look like a bad program. I'm currently taking a course called:
Distributive Systems.
We are learning about transmission lines and the inital part of the course
was interesting, now we got into all this Smith Chart stuff and it's
slightly confusing as to what I'm trying to accomplish.
Thanks for the help.
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| Salmon Egg 2007-02-11, 1:25 pm |
| On 2/10/07 8:50 PM, in article
Sgxzh.155$tD2.30@newsread1.news.pas.earthlink.net, "VWWall"
<vwall@DEADearthlink.net> wrote:
> Salmon Egg wrote:
>
> Do you know of any program using ABCD matrices with complex elements?
> I've used APL in the past, but it's pretty complicated for use on a PC.
>
> I wrote a paper back in 1953, on transistor analysis using ABCD
> matrices. I never found an easy way to do the calculations required.
>
> With programs like SPICE, other methods are probably not very useful.
I am not all that much into programming since I retired. I have written
programs in BASIC and Pascal for optical thin-films (very similar to
electrical four-terminal applications). I have also adapted the technique
for analyzing optical resonators to an HP-67. I have used the same concepts
for Excel spread sheets.
Once you get started, it is pretty straight forward. As in all programming,
you have to kill any bugs or prevent them from hatching in the first place.
As for programming hints, I offer the following.
1. For vectors that matrices work upon, only the ratio counts.
The impedance is Z=V/I corresponding to matrix vector [V,I]. Thus, you can
use vectors with components [Z,1] to track impedance through a series of
four terminal networks using ABCD vectors. For optics, the local index is
n=H/E where E represents the electric field and H represents the magnetic
field.
2. What happens in the network or thin-films can be represented in several
ways. For example, you can track the impedance, or alternatively, the
forward and backward waves (in terms of a complex reflection coefficient).
These are related by similarity transformations. Similarity transformations
are part of a study of linear algebra and well worth understanding.
3. A short summary of ABCD matrices is given by Louis Pipes in the Condon
Handbook of Physics.
4. Way back, John Slater in the book Microwave Electronics discussed the
bilinear transformation as a conformal transformation of complex quantities.
Every EE should understand that backwards and forwards.
Bill
-- Fermez le Bush--about two years to go.
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| Salmon Egg 2007-02-11, 1:25 pm |
| On 2/11/07 8:11 AM, in article DumdnVb2kLrV3VLYnZ2dnUVZ_rPinZ2d@comcast.com,
"Peter" <private@private.com> wrote:
> "Tony" <GLK@London.Calling> wrote in news:eqm8it$3o1$1@aioe.org:
>
>
> Doesn't look like a bad program. I'm currently taking a course called:
> Distributive Systems.
>
> We are learning about transmission lines and the inital part of the course
> was interesting, now we got into all this Smith Chart stuff and it's
> slightly confusing as to what I'm trying to accomplish.
>
>
> Thanks for the help.
Think of the Smith chart as a plot in the complex reflection coefficient
plane. The same information provided by the Smith chart can be presented in
many other ways. That is why, in another post, I suggested learning linear
algebra including similarity transformations. Also consider bilinear
transformations as espoused by John Slater.
These concepts will be useful in many branches of technology. Some examples
are crystallography, cartography, optical thin-films, electron spin, and
many other scientific inquiry. The point to remember is that the same
mathematics describe many apparently diverse phenomena.
Bill
-- Fermez le Bush--about two years to go.
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| VWWall 2007-02-11, 5:25 pm |
| Salmon Egg wrote:
> On 2/10/07 8:50 PM, in article
> Sgxzh.155$tD2.30@newsread1.news.pas.earthlink.net, "VWWall"
> <vwall@DEADearthlink.net> wrote:
>
>
<snip>
>
> 3. A short summary of ABCD matrices is given by Louis Pipes in the Condon
> Handbook of Physics.
I have pipe's book "Matrix Methods for Engineering". What I was looking
for was a PC program for doing simple calculations with ABCD matrices
with complex elements. Such programs exist in APL, and there is a PC
version of APL, but this is too cumbersome.
>
> 4. Way back, John Slater in the book Microwave Electronics discussed the
> bilinear transformation as a conformal transformation of complex quantities.
> Every EE should understand that backwards and forwards.
I use the "slide rule" equivalent of the Smith Chart for RF
calculations. For thin film optics, my usage has been limited to
di-chroic reflectors. For these, ray tracing works.
--
Virg Wall
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| Salmon Egg 2007-02-11, 9:25 pm |
| On 2/11/07 11:57 AM, in article
gyKzh.419$x74.412@newsread4.news.pas.earthlink.net, "VWWall"
<vwall@DEADearthlink.net> wrote:
> I use the "slide rule" equivalent of the Smith Chart for RF
> calculations. For thin film optics, my usage has been limited to
> di-chroic reflectors. For these, ray tracing works.
I don't know what you mean by ray tracing in this context. If it is a way of
adding up partial reflections at each surface, the result can be treated as
a similarity transformation between impedance (or index) and reflection
coefficient.
bill
-- Fermez le Bush--about two years to go.
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