# Questions tagged [transmission-line]

A transmission line may refer to a cable or assembly that is designed to carry radio frequencies and must consider the wave nature of the signal. Coaxial cable is an example of a transmission line. It may also refer to high-voltage power transmission lines, used to transfer power from generating stations to consumers.

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### VF Parameter in a Transmission Line

For a lossless line, you have $Z_0=\sqrt{\frac{L}{C}}$ and $VF=\frac{1}{c\sqrt{LC}}$. For a line with R, L, G and C parameters, we have $Z_0=\sqrt{\frac{R+j\omega L}{G+j\omega C}}$. But how ...
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### Does using HVDC for distance transmission make theft of electricity easier to detect?

In particular, if you were going to try to steal power from HDVC transmission lines you'd need one cable attached to current going in 1 direction and the other attached to current flowing in the ...
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### How to figure out at which point a SWER line stops being economically feasible when compared to a regular single-phase line?

I wish to simulate a transmission line and it's losses according to load, length and type of conductor, each one having their own characteristics such as impedance, radius, cost, etc. My goal is to ...
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### Directional Coupler Terminals

I have a basic question about directional couplers. In this scheme each port is represented by one wire. What does it mean? The other terminal of each port is GND for all?
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### Leakage Inductance Coaxial Cable

I do not understand how a particular parasitic effect is model. I have read that on a coaxial cable there is a problem due to the fact that the external conductor's magnetic field crosses the air ...
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### What are the units when solving Transmission Line iterativelly?

I would like to know the conductancee,$C$, and capacitance,$G$, of my lossy transmission line which is configured as an open circuit. In such a case, I know that the expression that defines the ...
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### Transmission Line (strip line)

1) As written in the task the L and H should be greater than 20h and impedance should be 50 ohms. Please help to adjust these parameters so that after changing the L and H I still get 50 ohms. 2) In ...
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### AC transmission just requires live wire, why is neutral present

If I touch a live wire and stand on the ground I will die because a circuit is completed, so for any load if I connect one end to live and other to ground it should work right, then why is neutral ...
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### Permeability and permittivity measurement using Nicholson-Ross-Weir method

I am currently trying to implement the Nicholson-Ross-Weir method in order to extract complex permeability and permittivity values from transmission and reflection measurements using a VNA. For this, ...
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### Impedance matching and reflection

I have a simple question about reflection and impedance matching. Consider a voltage generator Vg with its output impedance Zg, and suppose it drives a load Zl. In order not to have reflection, we ...
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### Voltage transmission

For the sake of understanding, I shall refer to voltage as a "pushing force that causes electrons to move and hence generate current." Now, I know that this force is "built up" and does not flow(...
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### Transmission Line (shielded dual stripline )

Evaluate and illustrate: equipotential contours and a vector electric field distribution for . I got this result: and . I want to ask that, is the direction of the Electric field lines are correct?
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### Standing waves feedline length and dipole antenna feedline

so I have a question regarding reflections/characteristic impedance and there relation with a quarter wave transformer and its feed line. Now I have found this video very useful for visualising what ...
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### What exactly is Characteristic impedence in transmission lines? [duplicate]

Please help me to understand what does a characteristic impedance mean. I am unable to get the exact idea of what does it actually mean and its physical significance.
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### Deriving NEC wire reactance table values

I'm verifying the NEC impedance table manually (how it gets the values in the table). In the NEC list for AWG 1 above, the inductive reactance (Xl) for 1000 feet has value of 0.046 ohm for PVC ...
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### Cutoff or Corner Frequency for Coax Cable

I'm trying to understand better what the significance of the cutoff frequency for coax cables is. I have a case where a cable is considered for use at frequencies up to 3% higher than the manufacturer'...
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### Smith chart of λ/4 Transmission Line

I came across the following slide on power combiner circuit and I have questions about it. Why traverse across the upper half circle ? Why "ZT-line is the geometric mean of Zout and Zin." ?
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### Reflection of Electric field in open-circuited transmission line

Consider a parallel-wire or parallel-plate or coaxial transmission line, carrying TEM wave, which we model as E,H,V,I, each having a forward(+) and backward(-) wave. In terms of V,I, we define ...
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### How is Line and Phase Voltage the same for a Delta connected system?

I am having a little bit of confusion for some reason understanding how the phase and line voltage can be the same for a delta connected system, i understand why the current is different for the phase ...
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### Maximum VSWR that can be tolerated?

I am trying to solve the 2013 paper set by ISRO for electrical engineers. I wanted to verify if my answer to Question no 14 is correct. The maximum RMS current is 20A, so maximum tolerable RMS ...
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### Why current flows along a transmission line?

Say I don't have a ideal transmission line i.e resistance/length!=0. Also E-Field exists between the two conductor lines. How then current flows through the line? There is no E-Field along the line ...
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### Lossless Transmission Line Length vs Rise Time

I am trying to answer the question - Does a signal's rise time increase with the length of a lossless transmission line? - using LTspice simulation. Some references say that lossless transmission line ...
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### A source generator connected to a receiver with a lossy transmission line

Consider that we have a 50-ohm source generator that is connected to a 300 ohm transmission line. This line has a loss of 10 dB for every 100 ft and is connected to a 50 ohm receiver. The source ...
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### ADS harmonic balance discrepancies with sawtooth waveform

I am using ADS for a simulation where I am biasing a diode with a sawtooth waveform. The sawtooth source provided by ADS, and 3 harmonics are specified There are different phase delays across the ...
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### How do I stop signal looping with I/O port in this communication system

I am still a student. When I am designing communication system I am facing this problem: As shown in the figure I need to communicate with Master and Slave. But Master and Slave have single I/O port ...
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### Matrix-Vector equation for active and reactive power in a transmission line

Suppose that we know vtilde (the complex voltage phasor vector at all buses), C the incidence matrix for a network, ...
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### How much power can transit through a power line linking generation and load?

First things first I am not an electrical engineer at all so please bear that in mind when you reply/comment. I am looking at the following problem, I have a power line which connects a windfarm to a ...
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### Single-line power transmission of 1MW over 35,000km [closed]

This question posted on the physics stack exchange has not received much attention. I thought the audience here might be more able to answer it. Background A space elevator is mechanism to provide ...
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### Microstrip transmission line impedance calculation

I'm attempting to calculate the necessary trace width of a PCB transmission line in order to have a characteristic impedance of 50ohm. However, different online calculators are giving me slightly ...
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### Can I use a RF and/or Time-domain reflectometer to find 'wet contact'?

Friends of mine have a circuit where the RCD trips but only after prolonged rain. There are a number of garden and security lights on that circuit so I very much suspect there is a junction box where ...
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### Why is the pulse reflection becoming like this in pulse?

I use mosfet to generate a pulse, input the pulse into the transmission line, and after the reflection, test the waveform as shown. Why did the third reflected waveform become like this? I calculated ...
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### Cut-off frequency in coaxial cable

The cut-off frequency of an RL circuit is described by the following equation: $$f = \frac{R}{2\pi L}$$ where R is the resistance of the circuit and L is the inductance. Applying this equation to a ...
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### Half-wavelength lossless transmission: magnetic energy and electric energy balance

I'm studying transmission lines and came up with a problem about a lossless transmission line that has a length equal to half the wavelength of the line. My book computes the complex power at the ...
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### Effect of source output impedance on reflections in a transmission line

For preventing reflections when the frequencies are higher or close to the transmission line length, for a 50 Ohm coaxial cable a 50 Ohm termination resistor is recommended. simulate this circuit &...
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### Paralleling LVPECL outputs?

I have a pretty unusual application here, where I need to drive a fast differential signal fanning out into 8+ 100ohm transmission lines. The unusual part is this: the transmission lines must be ...
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### Open Neutral Service Detector/Disconnector

Who has built an open neutral service detector that can disable the 120v circuits when the neutral opens accidentally (in the USA 120/240v split ac system)? Remember these words by Mike Holt: https://...
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### Transmission line with a resistor. What happens after a long time?

Ok so I'm analyzing a problem with a very simple lossless transmission line: In my case $$R=20 \Omega$$ and I have to find the evolution of uL(t) So I had no problem doing the first iterations. I ...
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### Transmission Line: Converting from impedance to admittance. Why?

If we want to find the input impedance of this given transmission line problem, why is it advantageous to switch the quantities from impedance to admittance?
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### Capacitance of short length transmission lines

I would like to simulate a short length transmission line in MATLAB/Simulink. In the library, there is a block that simulates a transmission line. The parameters that are required are the resistance R,...
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### How to explain the reflected voltage on the oscilloscope when a pulse is sent through a transmission line with a capacitor at the load?

This is waveform that I got on the osciloscopewhen experimenting in the lab. A pulse was sent through the coaxial cable was used with a capacitor at the load. I have my own idea why is this happening ...
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### Why is the top of the transmission line reflected pulse reduced?

I use this circuit to simulate the transmission line reflection, why the distortion occurs when the pulse signal is reflected back to the source. Only when the output impedance of the MOSFET pulse ...
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### Creating chained digital current loop

I need to send some digital data and power for long distance (around 60 meters) using only 3 wires. Data speed is low, something like 100bps is enough, 1000bps would be perfect (12.5Bps and 125Bps). ...
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### Connected RF Trace to Multiple Pads

I'm trying to improve my RF routing skills. I want to connect a 450 MHz trace (21mil width) to a RF6886TR13 power amplifier that has 6 RF_OUT pins. What is the best way to make this connection? I've ...
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### Does LVDS always need 100 ohm differential impedance?

LVDS pairs need 100 ohms differential impedance. However, I am having trouble achieving that in my design. My design requires that the pairs travel over very thin flexible PCB, about 50mm total ...
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### How to determine the frequencies in which the L&C model of an artificial transmission line works?

I want to model an artificial transmission line with L & C. So far I used the following circuit and used the values of L=400 pH and C=0.16 pF so that Z=sqrt(L/C)=50 ohms. So, expected S21 and S31 ...