Transmission Line - Science topic

in transmission line differential protection this a big issue

Hi,

I get confused about the CST calculations for reflection and transmission values (S- S-Parameters) for different kinds of transmission lines.

1)First could you please let me know where is the evanescent port mode selection available in CST for waveguide port?

2)If I want to see the S11 parameters of a rectangular waveguide, how does the CST calculate it?

Explain more:

The input impedance of a rectangular waveguide is its wave impedance of dominate mode. So the Zte impedance is not fixed and it varies with frequency. (attachment formula)

So, what type of and what value of waveguide port impedance is considered, for calculating the S11 parameters during the total bandwidth of a dominant mode and also more than dominant mode bandwidth?

3) If the type of TLs are not common or some changes are made, how does CST calculate the S11 for these structures? For popular TLs such as waveguides, we have a common formula.

I appreciate your time and explanation in advance.

Like, I have simulated GCPW with 5.4 mm, I get the phase of 107, but when I simulated 10.8 mm which is a multiple of 5.4mm I get the phase difference of 145 rather than 107+107=214 degrees and so on. I also attached my presentation with this question.

I am designing two RF tracks (Transmission lines) based on Grounded Coplanar waveguide. The length of both tracks is same, but there is still a phase difference between two tracks.

How do we combine the COVs of two independent, uncorrelated variables of different probability distributions?

Question

Weather-related loadings on electrical transmission lines involves incidence of wind on an iced conductor, separately and combined. Current US codes require transmission wires and structures be checked for the following load cases:

L1 Extreme Wind (high wind loads on bare conductors, upto 150 mph or 230 kmph)

L2 Extreme Ice (accumulated radial freezing ice, sometimes upto 2” to 4” in thickness)

L3 Combined Ice and Wind (¼” to ½” ice with variable winds, usually 20 mph to 40 mph)

Wind speeds are often considered to follow a Weibull or Extreme Value type distributions) while ice is generally known to be a Normal distribution. Some known COVs (coefficients of variation) are:

C1 Ice: 0.09

C2 Wind: 0.18 to 0.20

If one considers the load case L3, as shown in the sketch below, the Resultant of the ice load (V) and wind load (T) – both in force units per unit length of cable – can be expressed as:

Force Resultant R = √(V2 + T2)

Can this vectorial approach be valid for a resultant COV? Say COVR = √(C12+ C22)?

Note: Ice and Wind are totally independent variables and possess no statistical correlation whatsoever.

📷

Equations to calculate ice and wind loads are available in standard textbooks. Wind pressure p (psf) is generally approximated as p = 0.00256*S2 where S is the wind speed in miles per hour.

how to calculate the length of feedline or transmission line of microstrip patch antenna? Is there any particular formula?

In case there is a ready-made Matlab roll, I will be thankful

I'm trying to design a tunable microstrip combline filter with its initial f0 at 2.45GHz, with my resonator's electrical length at 45 degrees to provide maximum tuning range. I'm having problems with my CST simulation, where I'm trying to find the unloaded Q-factor of a resonator. I don't trust the results I'm getting (a Q0 of over 1000 for a 18um copper trace on a Rogers substrate, which I thought would be below 300) and am wondering if I'm using CST correctly.

The only thing I think can be wrong with the dimensions is that I might have chosen a PCB with too thin or thick a dielectric thickness. What are some common thicknesses used for applications at 2.45GHz?

The below list is the steps that I've followed. Hopefully something erroneous pops up to someone more experienced than I.

I've set up the simulation for Q0 extraction as follows:

My goal is to get Q0 at my desired resonant frequency, but the mode frequencies CST gave me is not at 2.4GHz. I don't think it's a fault with the dimensions, but I could very well be wrong. I suspect I might have made a mistake in how I set up my simulation.

Please advise me on any possible errors I could be making, or perhaps better ways of going about the simulation.

I can't seem to find anything on YouTube detailing the process I'm embarking on, nor do the papers I've found detail exactly how they arrived at their filter's dimensions from simulation, they simply provide their resulting parameters.

Thank you for your time.

What is the most recent technique used in mitigating transmission losses?

Which readily available simulator can i use for lightning simulations on Transmission lines? also how do i perform, the simulations?

Im doing a tranmission line upgrading project and i need to make sumlations to that effect

I am implementing a microstrip band-pass filter with high-low impedance sections (stepped impedance). The impedance is varying between 12ohm and 182 ohm, Zmin, Zmax respectively. For lowest impedance section 12ohm and other Z values (typically below 100ohm), when i simulate these individual sections of strip in CST, the simulated line impedances are almost same as required. For highest impedance 182-ohm transmission line required minimum strip width is 0.100 mm. I used the Lincalc from ADS to extract the corresponding substrate h (for 182ohm, 0.100micron w) which turn out to be 2.4mm at 11.75GHz (center frequency), 9.15 epsilon. When I simulate this w,h (0.100mm,2.4mm) in CST to verify the 182ohm, the simulated line impedance give a value of around 90ohm. It happens to all Z values higher than 100ohm. The problem in S-param are the return loss, the required RL is 20dB but the simulated one is around 12dB. I want to know if high impedances (Z>100ohm which are not achieving in simulated case) is contributing in worse RL or there are other factors. If this is about high impedance section, then how i can implement it to achieve the desired 182 ohm.

SIL is define as when transmission line loaded with Impedance equal to its Surge Impedance ignoring Resistance and conductance. When Surge impedance is equal to load impedance the sending end and receiving end voltages are equal.

Hello

I want to design a riblet hybrid coupler (Short Slot Hybrid Coupler) in X-band.

1- What should be the length of the couple region, the distance between the two common walls?

2- What techniques can I use for phase shift?

If you know an article or book in this field, please introduce it

Thanks

Suitable compensator upto 500KV ac transmission line, where power level will increase for modern era with affordable cost.

In the MATLAB simulation model of any power system model taken from www.mathworks.com, the parameters of power system components like generator, transformer, transmission line, load etc are set according to 60 Hz american standard, how to convert parameters of all power system equipments from 60 Hz american standard to 50 Hz european standard. Is there any procedure or empirical formula for this ?

I just want the clue or idea. I am not asking for an exact answer ?

Hello,

I am using CST Studio to simulate an interdigital capacitor and to extract its S-parameters of it. in order to process those measurements and obtain the parasitic elements that it contains. However, when I calculate the equivalent capacitance and inductance of it, it has negative and imaginary values, which do not make any physical sense. Therefore, I wanted to know if I was simulating it in the correct way. I put two ports, one in the input, and another one in the output and I put all the boundary conditions in 'open'. About the ports, I calculated the microstrip ports using the CST macro. I have attached a picture of the design to make it more clear. (perspective, top and bottom view).

My question would be: Should I use these boundary conditions? Is this the correct way to put the ports? Should I do any modifications to obtain a coherent result?

Best Regards

I face a very lossy line (cryogenic harness) with L = 320 nH/m, C = 60 pF/m and R = 10Ω/m characteristics. I can estimate the characteristic impedance of this transmission line as Z0=√L/C~70Ω. with 2 meters length, the lossy part is about R = 20 Ω. My simple question, is, if I want to amplify the end of this line with a good input matching, what LNA input impedance have I to match ? Z0 line impedance ? Z0 "+" R line impedance "+" resistance? Source impedance Rs? Source impedance Rs + losses R?

why the series compensated transmission lines connected to hydro power stations don't face the problem of subsynchronous resonance but the series compensated transmission lines connected to thermal or nuclear power stations or wind power stations faces the problem of subsynchronous resonance ?

As I mentioned above reviewer has asked me to make changes, like write down complete details about faults in the smart grid though my paper is about faults in transmission lines. My paper already has 12 pages if I add those irrelevant details it will increase the number of pages also. And another thing he has asked to merge all graphs which I think will make it too much complicated for reading. So how should I deny those changes which will not a kind of "offened" the reviewer?

What would be the possible dangers of using neodymium magnets near High voltage transmission lines or other high-voltage equipment? Is there any method by which we can make it safe to use?

Hello good time

What metals can be used in the design of high frequency devices such as Coaxial transmission lines , waveguides, coaxial to waveguide adapters? (Diamagnetic, paramagnetic or ferromagnetic)

Thank You

As the title says I am curious about whether the line transposition (eg - 1/3-1/3-1/3 transposition scheme) affects the behavior of fault-induced transients compared to an ideally transposed transmission line.

Is there any literature that has analyzed this topic?

i understood that every coaxial transmission line has a cut off frequency.

it seems strange to me, because the real behaviour of a transmission line in every frequency base on its equations is a delay time! so why the transmission line has a cut off frequency?

I am working on transmission lines, so i decided to simulate the real delay of electromagnetic waves in a cylindrical transmission line. base on my calculations and formulas, the delay of a wave in a 1 meter oil filled transmission line is 5ns , but when I simulate this simple structure in CST MICROWAVE STUDIO, I see a wrong time delay about 1 ns. so what do you think about this bug?

Where are PMUs installed exactly at the electric grid? at the substation level or transmission lines? is it possible to have PMUs at Distribution Level as well?

Thanks

I'd like to address one of my concerns regarding multiline TRL calibration. After calibrating a frequency, I occasionally did not get the expected result. If you look at my attachment, you'll notice that after calibration in some frequency ranges, it shows a sharp curve above 0dB (sometimes). Is there anyone who can say me why this type of error occurred?

what are parameters required to prove an SSPP Transmission line?

Below pictures are my design of a transmission line, for this simulation I set driven terminal. As you can see one side of the transmission line is differential pairs, another is single ended. If I want to see insertion loss of the transmission line how should I set the rectangular plot? Set "Show" to terminal and see St(Tline_T1,Tline_T3) and St(Tline_T2,Tline_T3) respectively? or set "Show" to differential pairs to see St(Diff1,Tline_T3)? or other?

Is it St(Diff1,Diff1) for return loss?

I am trying to design a CPW-GCPW tapered transition. Can anyone recommend a book or a reference for these types of transition structures? (Like how to calculated the tapered length etc.)

According

I've included an example picture. Is this transition followed by Quarter Wave transfer rules? or, Can anyone assist me in properly identifying this transition section?

If we connect the top and ground metal layers with a lot of Via, will the parasitic capacitance increase or decrease? As far as I know, it will reduce resistance.

Like the power transmission systems have transmission lines that carry impedance/admittance and this power transmission network can be seen as a graph with edges having weights as the admittances. Do the feeders in the distribution networks carry admittances that can be seen as edge weights?

From an admittance bus matrix one can construct a power network with buses connected with the transmission line having the admittances (being the entries of the bus matrix). Can this similar method be applied on feeders connecting busbars in a distribution network.

Why the fault current ?

Firstly, thank you very much for reading this question!

Now I am designing a T junction build-up with the transmission line. I find that I have to design this T junction within a dimension less than 1/4λ, but I have seen that I have to consider the transmission line effect when the electrical line pattern is >1/4λ (someone even says> 1/10λ)， and I do have seen some transmission drops for my interested band in simulation, seems like I have to do something with impedance matching.

Usually, we have those impedance matching schemes with 1/4 λ length(Quarter-wave impedance transformer), but they are too long for me. My question is, do we have any choices that we can achieve impedance matching with a smaller size impedance transformer?

Thank you all very much for the information and the ideas!

working principle, advantages, purpose

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case1 : when Radio frequency wave transmision line is loaded with matched impendace, then entire signal is taken by load without any reflections..

case 2: when a Radio frequency wave transmision line is loaded with short circuit, then entire signal is reflected back...

Now what happens when both the above cases are combined?

where will the signal go and how much will be the reflection coefficient?

will the matched impedance load get any signal?

I have written code for MTL model in MATLAB by referring an authors paper. The correctness of the waveforms obtained in time domain in MTL model depends on the data being used, which shouldn't be the case. For some data I get correct waveform , for others it gives absolutely erroneous result. I am not able to figure out where it might be going wrong. Could someone please guide me regarding this. Its been really long , I am trying to figure this out.

Unfortunately, this simplistic vision of RF and microwave circuit design often becomes blurred when test results are obtained that differ drastically from the beautiful simulation results. The reasons for this disparity may normally be traced to one of the following:

I read this above paragraph in a textbook, and didn't quite understand the sentence given in bold.

As of how does the above condition result in unwanted energy storage modes.

Thank you in advance

Power Network Expansion Planning is the problem of deciding the new transmission lines that should be added to an existing transmission network in order to satisfy system objectives efficiently. It is one of the main strategic decisions in power systems and has a deep, long-lasting impact on the operation of the system. Several challenges such as deregulation, renewable penetration, large-scale generation projects, market integration, and regional planning are discussed in the literature to some extent.

Hi,

I am trying to plot the dispersion diagram for a transmission line metamaterial IFA antenna, consisting of a capacitor in series and an inductor in parallel to the antenna.

As far as I know, the dispersion diagram is the plot of frequency vs. phase of S₂₁, as phase (theta) is beta*length.

But how to plot the dispersion diagram of an antenna which has only one port?

Kindly help me!

With Regards,

Suhas D

I would be glad if there's any way of finding the capacitance per unit length. since SIMULINK parameters block critically requires at least nearest values of all resistance, inductance, capacitance to get proper output results.

if we have a simple power system that consists of two generators and a one transmission line. One generator is operating at 50 Hz, and the other one is operating at 51 Hz. X is the line reactance, ignore line resistance. 

a)      What will be the nature of power flow P? If both generators have same voltage magnitude and the same phase angle?

b)       What will be the nature of power flow Q? If both generators have same voltage magnitude and the same phase angle?

c)     the generators have the same voltage magnitude but have different phase angle.

d)      the generators have the same voltage magnitude but have different phase angle.

I want to generate a sinusoidally varying impedance transmission line for the following specifications:

min. impedance 50ohm, max. impedance 170, period 10mm

I welcome all to this discussion.

Generally, we say that the algorithm giving fault location error of less than 5% is ok and lesser error indicates the superiority of the fault locator algorithm. Is any IEEE or other standard defines the limit of fault locator error?

This question is in the context of the transmission line protection.

Thank you for your time.

I want to design HVDC transmission line for simulation purpose in MATLAB but dont know how to set different parameters values any idea how can I do that? any artical/website/book from where I can learn that.

Hi, I need a power system model with 2 - bus, 2 - machines and a long-distance HVAC transmission line.

Would you mind providing with me all the necessary parameters of the system?

Bergeron line models will work for me.

Your help is greatly appreciated.

Thank you

The above model is useful in studying and testing the distance relay when a fault occurs at 75% of the length of the line because the line is divided into four equal parts.

Good day everyone. Is the Normalized Standard Deviation only parameter for measuring the accuracy of the Multiline TRL?

Thank you in advance to everyone.

Hello,

I'm designing a CPWG in the 30 GHz range in HFSS. I noticed that in my design the characteristic impedance is variable across my simulation range from 15-50 GHz. I think this is to be expected but more importantly the impedance of the line seems to be quite sensitive to the port definition. If I use the suggested wave port width the port overlaps with the coplanar grounds and the impedance drops from 52 ohm to 14 ohm. Any suggestions or tips on how to accurately do this and ensure no artifacts from the wave-port definition?

Hello, Here is my microstrip transmission line CST file which has been created by the Macro->calculated-> calculate analytical line impedance with these parameters Er=3 H=.6mm W=1.5mm L=10mm Frequency=5Ghz

But the S11 and S21 are not acceptable. I need to know what my problem is.

Hello,

I need to know why shorter impedance matching(IM) transmission line has higher Band width? (for example in designing IM circuit which has been calculated by Smith chart the shorter solution is preferred because of higher band with).

I am working on developing a model for transmission line failure in power gird. I need some information about capacity of each transmission line of IEEE 300-bus test case to identify lines that exceed their capacity (power/voltage/current). I couldn't find any data in the reference model.

Power system equipment needs periodic maintenance services for reliable operation with a lower forced outage frequency.

Maintenance scheduling is a program that optimally schedules the preventive maintenance for generation units and transmission lines. Through this program, the benefit of generation units and transmission lines, as well as the power system reliability, are taken into account simultaneously. Such programs maintain the system reliability by considering the simultaneous maintenance of power system components (particularly in low-price time periods of the year when generator owners want to temporarily keep their facilities out-of-service for maintenance services). Accordingly, preventive maintenance has different advantages as:

- Reducing failures frequency that prevents the reliability deterioration of the power system, particularly in both low-demand (decreasing the number of under-maintenance components) and high-demand (decreasing the forced outages of units) time periods

- Improving repair costs

- Retaining the useful lifespan of facilities

What other benefits are there for preventive maintenance?

Thanks

Hello everyone

Recently, I've been working on constructing the waveform for the simple PCB interconnect by means of existing algorithm, which means I don't want to use the commercial software.

To be simple, I suppose the topology is just TX + transmission line + RX (See Fig. 1)

At the beginning, I just wanted to quickly estimate the waveform with ideally initial waveform (See Fig. 2)

Unfortunately, I had no idea to estimate the TX output impedance and RX input impedance.

Eventually, I thought I had to build the waveform by means of interpreting the IBIS models.

There are [Pullup], [Pulldown], [POWER Clamp], [GND Clamp],... in the IBIS.

However, I don't know how to use them to construct the waveform and get the internal impedance.

My question : How to do that with the IBIS information?

(Suppose the IBIS is 4.2 version)

Thanks for your kind reading.

Is XLPE best insulator material for Medium Voltage underground electrical cables for Transmission Lines?

Normally the rated operation temperature for XLPE at this applicaction is 90 °C, So the temperature is not an issue , but what about the weight, cost and amount of material required for one meter of insulated Aluminum/Copper

Thank You!

Best Regards !:)

What is the maximum and minimum frequency in which a microstrip transmission line can operate without distortion for a particular length and width of the trace?

I need to calculate the values of R, X, G and B used in the t-model of the transmission line.

I have a 4 core wire and its data sheet, ( https://www.hesselmann.de/data-download/produktinfo/he-nycwy.pdf ).

How can I derive these values from this data?

I have been trying to implement Multiconductor transmission line(MTL) model for the transformer winding and then apply Numerical Inverse Laplace transform to get the time domain response in MATLAB. The equations I am using for MTL modelling are given in the paper attached below. The response I get doesn't match with the response given in the book. I am not able to figure out in my MTL code as to where is the mistake? Am I applying the MTL equations incorrectly or NILT is going wrong somewhere. Can someone please guide me regarding MTL modelling? Which equations are correct ?

Relation between electrostatic based problem and time harmonic electrodynamics problem.

Recently, I'd like to collect some formulas for some specific transmission line structures in PCB (single-ended stripline, single-ended microstrip line, etc)

I found that there is no formula related to the impedance of the microstrip line with solder mask (the region above the solder mask treated as the vacuum or the air)

Is there any suggestion to find that?

Thank your reading

R & X is ohm/km.

Hello everyone.

I want to research an s-parameters result of a dielectric cylindrical rod in CST software. which port can be used for full dielectric rod or full dielectric transmission lines?

I am trying to construct a microwave spoof plasmonic transmission line in CST. In particular, I intend to replicate the results of the paper, Broadband and high-efficiency conversion from guided waves to spoof surface plasmon polaritons. (https://doi.org/10.1002/lpor.201300118). I designed the unit cell in CST. I thought that using VBA macros, I would be able to copy, paste, translate, and boolean add my unit cells, to get the entire transmission line. However, this method didn't work. I am currently trying to design the transmission line in Autocad and import it to CST. I am hoping that it works. Still, I wanted to know if there are any other ways to do this. Thanks in advance!

I have dataset which shows the length of power lines. I need to classify the lines based on the line length. Is there a rule to classify the High voltage (HV) and low voltage (LV) lines based on line length? For instance, can we say lines below 500m (meters) are considered as LV lines and lines above this length are HV lines?

In strings, standing waves of particular frequency is possible only at specific length of string. But in transmission lines, no such conditions exist? What happens to the reflected wave when it reaches the source?

I want to make array by unit cells which I designed. now I want to feed this array. and I will use

tapered microstrip transmission line. actually I calculated the width and length of the tapered microstrip line with the formula in papers. but I don't know how to optimize the line with HFSS. because I don't know what should be value of the Zin in array input point. my means input Characteristic Impedance for Microstrip transmission is Z0 = 50 but output Impedance for tapered microstrip transmission line value should be how much?.

I want to test RF PCBs/ Modules for defect diagnosis. Can anyone please recommend or share a comprehensive document which can help me learn procedures to test the individual active, passive RF components and the transmission lines.

P.S : I have almost all the requisite equipment like VNA, SA, Power meter etc available with me.

400kV Double circuit Transmission line with a line length of 230kM without any compensation/PIR have 390kV ZnO surge arrester on both sides. When the bus voltage of either end approaches 420kV, the charging transient causes failure of Surge arrester. In PSCAD modelling, switching over voltage of 800kVp has been noticed. While the SA is designed to withstand 650kVp for 5 cycle. What could be cause of failure of SA?