endobj Quite Universal Circuit Simulator A circuit simulator with graphical user interface (GUI) Status: Beta. magnitude (i.e. There are also over 2,000 standard digital parts including all the usual 7400 families, CD4000 CMOS, and even ECL. including a "nomogram trick" to calculate a matching compensation TML stub, Wikipedia's Smith chart (a beautiful vector image in SVG format), By: Frank Rysanek [ rysanek AT fccps DOT cz ] in January 2017, The S-parameters generally speak about transfer of, At a first glance, the matrix of S-parameters is a shallow/superficial
"spacing of nodes" in the Smith chart :-), Schematic with a higher impedance resonator (lower Q), Charts with a higher impedance resonator (lower Q)
Note the resulting shape on the Smith chart, the differences
and reactance vertically. %äüöß the network is passive
Now how do I go about this,
I can sketch some circuits in Qucs. QUCS studio allows us to easily predict the performance of these networks. After that simulation has finished you can view the simulation results on a presentation page or window. for 0.02 ʊ ("mho" - synonymous to Siemens) as the center point. %PDF-1.4 quite fit in the "sequence of thought"... For some practical use of the Smith chart "nomogram"
Qucs Project official mirror. in a circular plot. both versions resonate at 50 MHz, but each one with a different Q. in fact only the "reflection" S-parameters (diagonal members
The "power transfer"
6 RF and Microwave Circuit Design Figure 4-2 Input impedance showing the resonance frequency at m1 The input impedance of the series RLC resonant circuit is given by, C Z in R j L j 1 where, = 2πf is the angular frequency in radian per second. Impedance and Admittance charts is identical :-) (is it?). �.�� )@GG�R)W��-J��1�s����Q�#č�% background maths by heart. I got intrigued, because this
I am under linux, and while I could try wine to use the smith chart simulation software, I was wondering if I could use qucs or qucs-s for simulating the matching circuit. and cannot amplify - unless the network is an amplifier maybe? as a basis for your own tweaks/experiments. Note how the visual mapping of the S-parameters in the
<> Bode plot. further qualified by conditions. We didn't try to put every last line on the chart, most times you use a Smith Chart you are more interested in approximate locations (is it … way of saying "we want to describe the, At a closer look, i.e. as "lumped element" LC circuits? nominal impedance = the center point is typically 50 Ω. or stubs, read the primary sources - see references below. the Admittance flavour of the Smith chart is typically calibrated
in one package. Smith chart. trivial example circuits and simulations = a Qucs project
2: Aug: 2005: Setup link for Qucs RPM packages. �����o����P,�+. As a consequence, some of my
to the signal sources) plays a role in the Q. <> 3. A Qucs Tutorial for RF Transmission Lines Pere Pal a-Sch onw alder February 2012 1 Simple Transmission Line in the Time Domain Let’s start with a simple circuit composed of a voltage generator, a transmission line and a load. This will be our rst circuit, which will be built step by step: ... ection coe cients plotted on a Smith Chart: 9. ��G��u�[�3��M�$\5G���=�*e�2�s�Y��^��9�-ٮ�Í���R-��ov(��b�Z�*!��г���"��}�p��. - Qucs - Quite Universal Circuit Simulator Matching Circuits Creating matching circuits is an often needed task in microwave technology. Have them :-) and use them
Microwaves101 has a good intro on that. THE SMITH CHART JEREMY HALEY, WG9T LONGMONT AMATEUR RADIO CLUB. Wikipedia on Admittance (and its relationship to Impedance), Microwaves101 on the Smith chart,
answers. The Smith chart is typically used to display the reflection coefficient on a particular port, rather than power transfer between ports (although the S-parameters for that are certainly available). transfer and reflection related
The Smith Chart allows easy calculation of the transformation of a complex load impedance through an arbitrary length of transmission line. QUCS has a graphical interface for schematic capture. S-parameters
advantages for network analysis in the way of "coupling
Impedance as a function of frequency is a complex number, consisting of a real resistance and an imaginary reactance. Impedance chart on the left, admittance chart on the right. 2 Longmont Amateur Radio Club RESISTANCE, REACTANCE, AND IMPEDANCE RESISTANCE Energy conversion to heat. This will automatically set up the matrix of N by N ports. (Well... not all that useful, as I later concluded, but anyway. flavour of the Smith chart, "for practical reasons". I would re-phrase those vague statements
(0.0.19 RC as of this writing) turns out to be an excellent educational
You can add in additional resistors to simulate real world losses. (kudos to Microwaves101.com):
I could then try fiddling with some
These are the neccessary steps: Perform an S-parameter simulation in order to calculate the reflexion coefficient. 2 0 obj This component looks like a voltage source with a series resistor
from port to port". = compensating impedance mismatches with lumped LC elements
2. The filter synthesis window will open. And, Qucs contains
An S-parameter Bode plot in Qucs displays the "power transfer"
OpenEMS scripts dependencies : OpenEMS ( octave-openems package available on Debian 10 based distros, octave-openEMS on openSUSE) It can also export Spice files if you want to use another engine or share designs with other Spice users. 5 0 obj Qucs is needed (even if you want to convert QucsStudio files), be sure it is installed and accessible from your PATH variable. statements below are likely incorrect :-) or need to be
I'm not an EE graduate, but practical electronics has always been
that an LC circuit always results in a neat ring :-). it seems that each "S-parameter" (a cell in the matrix, such as S21)
The Quite Universal Circuit Simulator (QUCS) is an open source electronics circuit simulator software released under the GPL, and is still under development. Simulation data can be represented in various types of diagrams, including Smith-Chart, Cartesian, Tabular, Polar, Smith-Polar combination, 3D-Cartesian, Locus Curve, Timing Diagram and Truth Table. QUCS has a graphical interface for schematic capture. The United States Particle Accelerator School provides graduate-level training and workforce development in the science of particle beams and their associated accelerator technologies. This article describes an extremely simple method of implementing a Smith Chart using the built‑in graphing capability of any modern spreadsheet program (Excel is used in this example). have enough of a maths background to start "properly from the ground up". The output of these analyses can be expressed in various forms like the Smith-Chart, Cartesian, Tabular, Polar, Smith-Polar combination, 3D-Cartesian, Locus Curve, … and similarities between the impedance and admittance version
stream Correspondingly,
This is just the start however. We've created a Smith chart within Excel. does it actually work? of the S-parameter matrix) are ever plotted in the impedance
Depending on the ratio between R, and L, C on the Smith Chart an arc of circle will be displayed, terminating on a single point, going to high frequency or on a series of circles. The Smith chart in Qucs picks the "impedance" layer of the S-parameter set (rather than power transfer). as I was simulating some stuff in Qucs, I came across the S-parameters
Once you compute the simulation, in the graphing tab you can
and the
and the Smith chart (once again). Courses are hosted by leading universities across the U.S.A. This point should probably be someplace at the top, but it doesn't
stuff I've gleaned from all the tutorials I've read. Essentially, you need a "power source" for each port of your circuit. It makes perfect sense to plot several different S-matrix
22: Jul: 2005: Released Qucs 0.0.7 ! wade into antenna and RF technology on my job every now and then. This training is not otherwise available to the scientific and engineering communities. QuickSmith - Free Interactive Open Source Smith chart for Web and Mobile for impedance matching - A Tutorial It also allows the calculation of the admittance Y = 1/Z of an impedance. QUCS has a graphical interface for schematic capture. Qucs can do this automatically. not phase) vs. frequency. x��YK�#7�ϯ�s`�*IՒ`0x�ma �%�$l��%?���Rw���B�mU������ ��Nf�7'7��Nq���������K�������K�0ys���oӇ�0��^��_��{y���Y�'�k�lB�'K� "I|f�{x0�|�Ɲ�Ã��u6A^�|�������w3��W0g��X��ȳl����������oy;R���EV?���%4ڢ0.��N�~����0=�=�#6�G,s%`d1�(��l=^̓yԏ�D����#�OH�)A`$�&"�t�_BV��g�\Z^�i�`RV�
!�&yU3���?F�Ɠ�[\���d̯9`*@;6��SZ�*�Y�%"��ob��ߕ�Vd�xj�y�����D�=�"��Jl��T�Mμ�l����D�3o�XQ�h�n碧B���G�ΚB����ʂ[h%6n|n,_((ƫ�M̲�K�͆90g�OKf\Z2eKd���b�tI� �B4v�� Some sources (Microwaves101 if memory serves) claim that
Smith chart ... To simulate RF networks, I recently upgraded from RFSim99 to Quite Universal Circuit Simulator (Qucs) which is a free-software electronics circuit simulator released under GPL. Create a new schematic if you need to. 3 0 obj directory containing some ready files. Qucs, briefly for Quite Universal Circuit Simulator, is an integrated circuit simulator which means you are able to setup a circuit with a graphical user interface (GUI) and simulate the large-signal, small-signal and noise behaviour of the circuit. Actually, a "quarter-wave shorted stub" (generally any
Let’s create a simple 3-pole, low pass, Bessel type LC filter. (or other software available on linux). My experiments in Qucs have resulted in some
is actually a. 1. in your charts/plots. x��O�j1��[���-˹+�)B�$���GZ�H7�`W7�e��� �De $�"�����oOpfr|ף�M��XT�'d�}g��Nbi��O�}���`BT�f�`|7���5�")�E��c���3���=���~as�� �n*F�D�\��4���+z���'bI%]>�������퍸���K?����� �g���8$��V���6���:S-)�l�e/ The Smith chart in Qucs picks the "impedance" layer of the
The number of models supported for active devices is impressive and includes some very recent MOSFET models, not just the old standard models. If the impedance measured at the low frequency is Z low, then R = ... (QUCS) from SourceForge.net. And that the Admittance flavour of the chart has significant
Simulation data can be represented in various types of diagrams, including Smith-Chart, Cartesian, Tabular, Polar, Smith-Polar combination, 3D-Cartesian, Locus Curve, Timing Diagram and Truth Table. Stuff that has some practical use, without you knowing all the
You will be offered the S-matrix members for use
what variables are on each axis, why the grid is curved,
Note how this affects the shape of the Bode plot and the
It's just a matter of creating equations for semi-circles, something any nerd can do. Power and noise matching tool with smith chart (one-port and two-port matching). As a bonus, we tried it under Wine a… stream [��#�����'�8�ku���pEJ��SY�\�n
2{S2���"3+7���:�'�b>d�.�R�!CQ��w�����V�L���xY :-)
The Impedance flavour of the Smith chart has resistance horizontally
Use with a grain of salt. Contribute to Qucs/qucs development by creating an account on GitHub. endobj in the Smith chart - and the interwebs provided surprisingly few
of the Smith chart, and the differences vs. similarities
I have an itching to summarize, in lay man terms, some of the
parameters all in one picture. of the schematic: the difference is in the L and C values,
is strictly in a range between 0 and 1, i.e. Try playing with the values yourselfs (data download follows below). component values to see the effect of my changes...". Impedance chart on the left, admittance chart on the right, Schematic with a lower impedance resonator (higher Q), Charts with a lower impedance resonator (higher Q)
Also updated the installer for Win32. series resistors to two different power sources. select the two versions of the Smith chart, or a "cartesian"
but the resistance from the signal sources (and also the one intrinsic
Smith chart example test with a band pass filter: Digital simulation: DigitalAdder_prj.tar.gz: four-bit adder using one-bit halfadders and fulladders: flip_flops_models_tran_prj.zip: collection of flip-flop models usable for digital as well as transient simulation: BCD_prj.tar.gz: four-bit synchronous BCD counter: Harmonic balance: diode_hb.sch The impedance is represented by a normalized … When stability circles are large and situated on different sides of smith chart (they look very chaotic at lower frequencies) then I must change scale of the chart a lot to see whats going on. No point in reproducing this here. The resonant cell itself consists of ideal L and C,
Next, you need an "S-parameter simulation". once you start graphing the S-parameters,
Hi I'm trying to learn rf amplifiers with qucs and I've encountered a problem when trying to investigate stability circles of a transistor. that the curved grid of the Smith chart is shaped exactly such
when working with resonators,
It can also read just about any regular Spice or IBIS model. my hobby (albeit typically on the back burner) and I also happen to
Have you ever noticed, e.g. I started out by spending some time reading primers on the
The Impedance flavour of the Smith chart is "calibrated" for a particular
Simulation data can be represented in various types of diagrams, including Smith-Chart, Cartesian, Tabular, Polar, Smith-Polar combination, 3D-Cartesian, Locus Curve, Timing Diagram and Truth Table. For our example, we are doing an LC filter, Pi type (where the first branch is a shunt), Bessel type, Low pass, Third (order – scroll down to the Example for mathematical info), and a corner frequencyof 1 GHz. At the top menu, under “Tools”, click “Filter synthesis”. Note: speaking of Q, this is affected by the resistors
I've taken screenshots of two, slightly different versions
wavelength-tuned transmission-line section) also results
The following is an LC circuit, coupled by two different
the distinction between the impedance vs. admittance version of the
stuff seemd related to my "research into directional couplers". Fill in the parameters as desired. in my own vague way: Although I've never seen this written anywhere, it seems to me
some Smith charts in the graphing tabs. There are also quite a few examples provided. However, the Smith charts method of displaying data have managed to retain its prefere… 236 Smith chart
The current version of Qucs
among the various S-parameters. Other features include the transmission line calculator, Filter synthesis, Smith-Chart tool for power and noise matching, Attenuator design synthesis, Device model and subcircuit library manager, Optimizer for analog designs, the Verilog-A interface, Support for multiple languages (GUI and internal help system), Subcircuit (including parameters) hierarchy, Powerful data post-processing possible using equations … The Smith Chart, named after its Inventor Phillip Smith, developed in the 1940s, is essentially a polar plotof the complex reflection coefficient for arbitrary impedance. If a Smith Chart is included in a spreadsheet, it is usually an image pasted in from some other application. Admittance/impedance marker data management at Smith chart diagrams. in the schematic. Click the images for a full size version. $1 5hy $1 &rqwhqwv 0hdvxuhphqw ri 3&' 5) dqdorj sdudphwhuv 9hulilfdwlrq ri wkh 4 idfwru lq wkh wlph grpdlq endstream On a recent encounter with WiFi antennas and directional couplers,
It was originally developed to be used for solving complex maths problem around transmission lines and matching circuits which has now been replaced by computer software. In this case, the corner frequency will … 4: Jul: 2005: Project renaming to "Quite Universal Circuit Simulator" according to … that tuned transmission line stubs do not work exactly the same
I was wondering what some typical circuits looked like
S-parameter set (rather than power transfer). toy when it comes to S-parameters and the Smith chart. REACTANCE Capacitance: Energy storage in electric field. Allows you to view gamma or an impedance/admittance on the Smith Chart and view parameters of any other point in the chart Wheeler Stripline Impedance Calculator: Free online javascript-based calculator Amanogawa's transmission line tools (FREE): 24 TL online tools in Java, very nice! members in the same Bode plot, i.e. It is then possible to play with the component values to test out the effect of using real-world values. ), I felt I had to "start from someplace in the middle", as I didn't