as "lumped element" LC circuits? 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. 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. in one package. I got intrigued, because this 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, … $1 5hy $1 &rqwhqwv 0hdvxuhphqw ri 3&' 5) dqdorj sdudphwhuv 9hulilfdwlrq ri wkh 4 idfwru lq wkh wlph grpdlq (kudos to Microwaves101.com): when working with resonators, The Smith Chart allows easy calculation of the transformation of a complex load impedance through an arbitrary length of transmission line. Also updated the installer for Win32. 5 0 obj Simulation data can be represented in various types of diagrams, including Smith-Chart, Cartesian, Tabular, Polar, Smith-Polar combination, 3D-Cartesian, Locus Curve, Timing Diagram and Truth Table. If the impedance measured at the low frequency is Z low, then R = ... (QUCS) from SourceForge.net. - Qucs - Quite Universal Circuit Simulator Matching Circuits Creating matching circuits is an often needed task in microwave technology. as I was simulating some stuff in Qucs, I came across the S-parameters <> [��#�����'�8�ku���pEJ��SY�\�n 2{S2���"3+7���:�'�b>d�.�R�!CQ��w�����V�L���xY wade into antenna and RF technology on my job every now and then. The resonant cell itself consists of ideal L and C, Quite Universal Circuit Simulator A circuit simulator with graphical user interface (GUI) Status: Beta. (or other software available on linux). 2. some Smith charts in the graphing tabs. The United States Particle Accelerator School provides graduate-level training and workforce development in the science of particle beams and their associated accelerator technologies. I started out by spending some time reading primers on the including a "nomogram trick" to calculate a matching compensation TML stub, Wikipedia's Smith chart (a beautiful vector image in SVG format), By: Frank Rysanek [ rysanek AT fccps DOT cz ] in January 2017, The S-parameters generally speak about transfer of, At a first glance, the matrix of S-parameters is a shallow/superficial Impedance and Admittance charts is identical :-) (is it?). The Smith chart in Qucs picks the "impedance" layer of the what variables are on each axis, why the grid is curved, ��G��u�[�3��M�$\5G���=�*e�2�s�Y��^��9�-ٮ�Í���R-��ov(��b�Z�*!��г���"��}�p��. It can also export Spice files if you want to use another engine or share designs with other Spice users. As a consequence, some of my Let’s create a simple 3-pole, low pass, Bessel type LC filter. On a recent encounter with WiFi antennas and directional couplers, 4: Jul: 2005: Project renaming to "Quite Universal Circuit Simulator" according to … You can add in additional resistors to simulate real world losses. S-parameters Admittance/impedance marker data management at Smith chart diagrams. among the various S-parameters. (Well... not all that useful, as I later concluded, but anyway. However, the Smith charts method of displaying data have managed to retain its prefere… If a Smith Chart is included in a spreadsheet, it is usually an image pasted in from some other application. flavour of the Smith chart, "for practical reasons". nominal impedance = the center point is typically 50 Ω. the distinction between the impedance vs. admittance version of the 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. These are the neccessary steps: Perform an S-parameter simulation in order to calculate the reflexion coefficient. 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 … my hobby (albeit typically on the back burner) and I also happen to of the Smith chart, and the differences vs. similarities This will automatically set up the matrix of N by N ports. = compensating impedance mismatches with lumped LC elements At the top menu, under “Tools”, click “Filter synthesis”. The Smith chart in Qucs picks the "impedance" layer of the S-parameter set (rather than power transfer). stream %äüöß Power and noise matching tool with smith chart (one-port and two-port matching). There are also over 2,000 standard digital parts including all the usual 7400 families, CD4000 CMOS, and even ECL. <> Note: speaking of Q, this is affected by the resistors 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. There are also quite a few examples provided. REACTANCE Capacitance: Energy storage in electric field. :-) 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/ endstream advantages for network analysis in the way of "coupling (0.0.19 RC as of this writing) turns out to be an excellent educational transfer and reflection related endobj 2 Longmont Amateur Radio Club RESISTANCE, REACTANCE, AND IMPEDANCE RESISTANCE Energy conversion to heat. is strictly in a range between 0 and 1, i.e. magnitude (i.e. Smith chart that the curved grid of the Smith chart is shaped exactly such toy when it comes to S-parameters and the Smith chart. from port to port". 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. My experiments in Qucs have resulted in some members in the same Bode plot, i.e. It makes perfect sense to plot several different S-matrix This point should probably be someplace at the top, but it doesn't Impedance as a function of frequency is a complex number, consisting of a real resistance and an imaginary reactance. 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 … 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. 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). Next, you need an "S-parameter simulation". the network is passive further qualified by conditions. the Admittance flavour of the Smith chart is typically calibrated Have you ever noticed, e.g. And that the Admittance flavour of the chart has significant series resistors to two different power sources. Bode plot. After that simulation has finished you can view the simulation results on a presentation page or window. in fact only the "reflection" S-parameters (diagonal members This is just the start however. 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. Note how this affects the shape of the Bode plot and the not phase) vs. frequency. Qucs Project official mirror. This training is not otherwise available to the scientific and engineering communities. Contribute to Qucs/qucs development by creating an account on GitHub. We've created a Smith chart within Excel. The impedance is represented by a normalized … Smith chart. does it actually work? As a bonus, we tried it under Wine a… and cannot amplify - unless the network is an amplifier maybe? wavelength-tuned transmission-line section) also results in your charts/plots. stream 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. and the I can sketch some circuits in Qucs. Courses are hosted by leading universities across the U.S.A. and similarities between the impedance and admittance version quite fit in the "sequence of thought"... For some practical use of the Smith chart "nomogram" The filter synthesis window will open. statements below are likely incorrect :-) or need to be 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! in my own vague way: Although I've never seen this written anywhere, it seems to me Use with a grain of salt. but the resistance from the signal sources (and also the one intrinsic Stuff that has some practical use, without you knowing all the QUCS has a graphical interface for schematic capture. I have an itching to summarize, in lay man terms, some of the I've taken screenshots of two, slightly different versions or stubs, read the primary sources - see references below. It's just a matter of creating equations for semi-circles, something any nerd can do. Note how the visual mapping of the S-parameters in the "spacing of nodes" in the Smith chart :-), Schematic with a higher impedance resonator (lower Q), Charts with a higher impedance resonator (lower Q) QuickSmith - Free Interactive Open Source Smith chart for Web and Mobile for impedance matching - A Tutorial The "power transfer" QUCS studio allows us to easily predict the performance of these networks. 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. %PDF-1.4 component values to see the effect of my changes...". It also allows the calculation of the admittance Y = 1/Z of an impedance. An S-parameter Bode plot in Qucs displays the "power transfer" answers. I would re-phrase those vague statements have enough of a maths background to start "properly from the ground up". 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. stuff seemd related to my "research into directional couplers". It can also read just about any regular Spice or IBIS model. The current version of Qucs The number of models supported for active devices is impressive and includes some very recent MOSFET models, not just the old standard models. Correspondingly, 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). ), I felt I had to "start from someplace in the middle", as I didn't This will be our rst circuit, which will be built step by step: ... ection coe cients plotted on a Smith Chart: 9. and the Smith chart (once again). Once you compute the simulation, in the graphing tab you can in a circular plot. endobj Essentially, you need a "power source" for each port of your circuit. and reactance vertically. Impedance chart on the left, admittance chart on the right. Qucs can do this automatically. 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 it seems that each "S-parameter" (a cell in the matrix, such as S21) 2 0 obj Qucs is needed (even if you want to convert QucsStudio files), be sure it is installed and accessible from your PATH variable. I'm not an EE graduate, but practical electronics has always been of the S-parameter matrix) are ever plotted in the impedance 236 Some sources (Microwaves101 if memory serves) claim that The following is an LC circuit, coupled by two different 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) 2: Aug: 2005: Setup link for Qucs RPM packages. 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. in the schematic. �.�� )@GG�R)W��-J��1�s����Q�#č�% parameters all in one picture. Now how do I go about this, I was wondering what some typical circuits looked like Actually, a "quarter-wave shorted stub" (generally any The Impedance flavour of the Smith chart has resistance horizontally to the signal sources) plays a role in the Q. 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��œߕ�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�� trivial example circuits and simulations = a Qucs project as a basis for your own tweaks/experiments. 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