Standing Wave and Wave Propagation inside Copper Trace Simulation Software - Page 1
Forum section: electronics / projects

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 22, 2020, 08:26:32 am
content: i want to visualize in simulation program the effect of wave propagation and standing wave thats happening inside a length of transmission line, such as controlled impedance microstrip or simply a bare copper wire antenna. the input for the simulation are:1) source impedance (signal generator)2) transmission line's characteristic impedance and its length. conductor resistance value also usefull as in resistive coax cable3) wave propagation speed (factor wrt speed of light)3) load impedance at the end of transmission linethe output is visual simulation of wave on the length of transmission line, i can pick a point anywhere on the line and see voltage oscillation on that point. question:1) does this kind of software (Windows) exist? i cant find in google what i want.2) any materials needed if i want to make my own software? (i dont have a clue)i dont expect to dig into electromagnet propagation or maxwell equation or anything that happens in the air, just simply enough to see voltage potential oscillation inside a conductor. what i want is something like this, but it has too few input to make it usefull.https://www.physicsclassroom.com/Physics-Interactives/Waves-and-Sound/Standing-Wave-Patterns/Standing-Wave-Patterns-Interactive

author: daqq
author_rank: Super Contributor
timestamp: September 22, 2020, 10:11:55 am
content: Quote1):Free: openEMS + paraview + octave - there's a learning curve, but it works and they are all powerful tools.Commercial: Search for FDTD simulators, quick result:https://www.remcom.com/xfdtd-3d-em-simulation-software2):The basic math is complicated, but straightforward. The actual implementation... see openEMS. It's one of those applications for which HPC exists.

author: tggzzz
author_rank: Super Contributor
timestamp: September 22, 2020, 10:22:50 am
content: Don't use simulation where analytic solutions exist - as in this case.The equations are well known, graphs are available, and for better understanding you could plot the graphs from the equations yourself.

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 22, 2020, 10:37:45 am
content: Quote from: tggzzz on September 22, 2020, 10:22:50 ami mean... can you provide the link? so i can read and make my own program. i can just use sine formula and make some nice wave simulation, but impedance effect will not get accounted and hence less ideal simulation.Quote from: daqq on September 22, 2020, 10:11:55 ami've used HFSS, i think its similar grade to openEMS. afaik they dont show interactive (moving) wave. they only show some sort of still picture wave magnitude as rainbow pattern. i know we can get VSWR-vs-freq plot from them, but again, i need something interactive similar to link i've provided in OP.

author: tggzzz
author_rank: Super Contributor
timestamp: September 22, 2020, 10:41:04 am
content: Quote from: Mechatrommer on September 22, 2020, 10:37:45 amUse google. If you can't do that then it is unlikely you will be able to understand the answers anyway.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: September 22, 2020, 10:57:52 am
content: Quote from: Mechatrommer on September 22, 2020, 10:37:45 amWhile I applaud the people behind openEMS for their work, I would hesitate to call it 'similar grade to openEMS'.HFSS and similar can in fact plot moving fields, standing waves, in animation. I use it quite often.That said, I agree with tggzzz - you are looking for a more basic analytical solution. Simply start with the classic telegraphers equations, plus the equations for the reflection coefficient. The telegraphers equations tell you how a wave propagates along a line, and the reflection coefficient will tell you what wave is propagating in either direction based on the source and load. Total field is just the sum of the two.

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 22, 2020, 11:09:02 am
content: Quote from: tggzzz on September 22, 2020, 10:41:04 amgoogle with no keyword is useless... you still dont think i can google do you?whats the purpose of forum? well, google with less ideal keyword is better than post with no answer anywaynow i will google more, no need to wait answer in forum. at least i've tried.Quote from: TheUnnamedNewbie on September 22, 2020, 10:57:52 amah now i have some keyword to type in google thanks.(as i've already mentioned, i dont need maxwell equation, so i specifically asking for a simpler thing i just dont know what its name is)

author: tggzzz
author_rank: Super Contributor
timestamp: September 22, 2020, 11:16:40 am
content: Quote from: Mechatrommer on September 22, 2020, 11:09:02 amYou already had plenty of keywords - you had written them yourself in your first post!They would be more than sufficient for you to formulate more precisely directed queries.

author: Etesla
author_rank: Regular Contributor
timestamp: September 23, 2020, 01:00:57 pm
content: The software you are looking for is called CST microwave studio. I'm not sure how much it costs, I got it for free as a student. You can use it to view and simulate any mechanical structure and it's electrical properties in 3D.

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 23, 2020, 05:30:57 pm
content: they are the same thing imho... CST, HFSS, OpenEMS... they are Field Solver Simulator.. i read a little bit about telegrapher's equation, its a differential equation that only can be solved by some fancy numerical method such as monte carlo... there is no easy straight forward way for what i want (will read and find more)... and i cant find what i want in any field solver program based on reviews and introduction in youtube, at best i saw the typical 3d rainbow plot... keyword:interactive simulation openems

author: inginfo
author_rank: Newbie
timestamp: September 23, 2020, 08:57:14 pm
content: You can do such a simulation with Python / NumPy / SciPy. The electrical properties of the line must be described mathematically. A system of differential equations results, which can then be solved with the computer. See the attached example of an RG58 coaxial cable simulation.

author: rfeecs
author_rank: Frequent Contributor
timestamp: September 23, 2020, 10:59:46 pm
content: If all you want to do is look at the voltage along any point in the transmission line, you can use SPICE that has a transmission line element. For example, I believe LTSPICE has the element LTLIN, where you can specify the R, L, G, C parameters for a lossy line. You can divide the line in to two sections and connect a probe to the junction between the two sections. Varying the length of the sections should allow you to probe the voltage at any point.