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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How will the proper termination at one end while the other end is kept open avoids reflections in transmission line?
Consider a transmission line which is terminated with characteristic impedance at one end but other end is kept open, the reflections are not observed. I don't understand the mechanism behind. Please ...
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How much RF power can a microstrip line handle?
Transmission lines on printed circuit boards must be impedance controlled lines since we want to transmit the full power and avoid the reflections.
Microstrip lines have three parameters that we can ...
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Terminating Resistors on Ethernet Port
I'm using Ethernet (CAT5/5e/6) cables to communicate with the PCA9615 Differential I2C buffer. These cables roughly have a characteristic impedance of 100 ohms, but I have a few questions about ...
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What constitutes a transmission line?
Lets say I have a lossless coaxial cable with a characteristic impedance of 50 ohms. The length of the cable is very long compared to the the wavelength of the relevant signals on the coaxial cable. ...
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How does cross talk actually affect the signal?
Assuming there is one node that is connected to four wires/transmission lines, and a perfect step function(no rise time) is injected into the node, how does it show up on the four wires due to the ...
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Guided wavelength for a transmission line using MWO TXLINE
Is it possible to find the guided wavelength for a transmission line using Microwave Office's TXLINE?
I am trying to find the guided wavelength \$λ_g\$ for a transmission line with a characteristic ...
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How do reflections of a square wave cause ringing in transmission lines?
When a square wave is applied to a transmission line which is not terminated with its characteristic impedance, reflection and ringing occur.
I don't understand how sinusoidal ringing occurs when I ...
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“Rigorous” motivation behind the model of transmission line for microwave engineering
I am trying to understand under a rigorous enough point of view the model of transmission lines.
More specifically I am interested to this question under the context of microwave engineering.
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What is the effect of the reflection coefficient?
I know that the reflection coefficient is the ratio of the backwards wave with the forward wave in terms of the characteristic and load impedances. But what does this mean? Does this represent a loss ...
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Standing waves in Dipole antennas
I'm relatively new to antennas. In most of the textbooks, it is said that we want to minimize standing waves in the transmission lines by matching the characteristic impedance of the line with the ...
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Inductance of a three-phase transmission line
I was studying the difference between distribution and transmission lines and read that, because of the larger separation among the conductors, the transmission lines have comparatively higher flux ...
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How much average power delivered to each antenna?
I am confused if the characteristic impedance of line 1 is simply 50 ohms. Also, I know that \$P_{av} = P_{av}^i + P_{av}^r\$, but I do not have the voltage amplitude \$|V_o^+| \$ so I am unsure how ...
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Lumped parameter vs transmission line model for a piece of cable
I would like to model a piece of cable (less than 5m) over a frequency range of DC to \$1\mathrm{MHz}\$. I am however doubting if I can approximate it by a lumped parameter model (mainly at \$1\mathrm{...
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Meaning of “raised structure” in microwave networks
Can you help me to understand what "raised structure" means and why it determines the following property of the S matrix?
Reference: here.
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Path of a signal traveling on a mismatched transmission line
I have a basic question about the path of a signal traveling on a transmission line with a short circuit as termination.
Suppose that this line is driven by another line (at left) with Zc = 50 Ohm ...
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How is a transmission line with a different characterisitc impedance shown on the smith chart?
A transmission line can be shown on the smith chart as a clockwise rotation, each 180 degrees corresponding to a quarter wavelength. But this is when the characteristic impedance (Z0) of the ...
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Connecting CMOS sensor to (far away) PCB: understanding cable length
The problem is a bit complex due to the number of unknown parameters and my inexperience. I need a way to determine how far I can put the PCB from the sensor without problems in the transmission of ...
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Time Domain Measurements with Vector Analyzer
In my university I have done some time domain measurements with a VNA (by using the transform operation of the instrument). Precisely, I have selected the measurement of the real part of S11 while ...
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Measuring the impedance of a transmission line
I designed a Tem Cell and I need to measure its impedance which I have no idea how I can do that. I have tracking generator, signal generator and 50 ohm terminations. So how can I measure the ...
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Quantify Grid Stiffness
Being the stiffness of the grid its capability of maintaining the voltage constant despite small variations on load. Whereas, a weak grid would be easily affected by load variation and the voltage ...
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Does zero sequence current flow in line to line faults?
Assuming that there is a prefault load on a line,does zero sequence current flow during phase to phase faults ?
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Transmission Line Impedance 3 phase
I have the following question that I can't seem to figure out. The question ask to solve for the impedance of a 3ph transmission line. I've found the De (distance relative distance) and XL using the ...
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How to properly terminate this circuit (50ohm coaxial to oscilloscope)
I'm a bit confused how this type of circuit should be terminated. I have no experience with transmission lines, so I do not know where to put 50ohm resistor.
It's basically output from opamp, ...
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What is “tap line”?
I am reading this article (https://arxiv.org/ftp/arxiv/papers/1901/1901.02069.pdf) where I have come across this sentence: "we first designed a
parallel coupled Chebyshev bandpass filter as shown in ...
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Reflection Coefficient with Electric Field and Voltage
In different situations the input reflection coefficient (of a waveguide, of a transmission line etc) is defined differently.
Wikipedia says:
The reflection coefficient may also be established ...
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Can we reduce power consumption of digital interfaces by using high impedance transmission lines?
Transmission lines must be terminated with the same impedance as the transmission line has itself to get an impedance matching and avoid reflections at a high impedance end point. This termination ...
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Computation of the Scattering Matrix of a Transmission Line
let's consider this transmission line (with losses) in which a and b denote respectively the reflected and the incident waves at each port:
This exercise asks to find its scattering parameters ...
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Why do we get Non uniform plane waves along a transmission line?
I get that wave propagation will take place but why TEM mode is the only possible mode that can exist? And also why it is non-uniform?
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Voltage on a Transmission Line with Ideal Conductors
Let's consider a transmission line with Perfect Electric Conductors.
We know that if an external AC source is applied, we get a voltage waveform between the conductors which is function of the ...
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Confusion in understanding characteristic impedance and input impedance of an open circuited transmission line
The characteristic impedance Zo can be derived by considering LC sections throughout the line with open circuit at the end of the line, and this value is independent of length of the transmission line ...
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Transmission Line with Short Circuit and Inductor as Loads
let's consider this situation in which the two ports of a transmission line are connected to a short circuit and to an inductor:
The transmission line is supposed to be lossless. My book makes a ...
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Interpretation of scattering parameter
Currently I am (non-engineer) trying to understand the origin of measured scattering parameters with a vector network analyzer and a 2 port system. The second port is terminated with a matched load to ...
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Issue with high induced circulating current in 115kv underground line
We are facing a problem with high induced sheath current during line testing with cross bonding.
Initially, we got 27 amperes in link boxes when we injected 70 amperes in the line.
Later with a few ...
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Propagation Constant Expression in a Transmission Line
let's consider a generic transmission line:
Its wave vector Kz is equal to:
where
Then, I read also that it is true that:
where does this relation come from?
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Low and high impedance of low pass stepped impedance filter
I'm designing a low pass chebyshev filter using stepped impedance.
I'm using the book 'Microstrip Filters for RF/Microwave Applications' as a reference.
I have difficulty understanding how low and ...
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Noise in transmission system
Does external noise (not electrical noise) affect system voltage? If so how does a source of sound energy distort a voltage waveform?
https://youtu.be/4TCnYYpZxEc
What exactly is happening in this ...
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How to measure the actual length of a long twisted pair?
Sometimes we might need to know the exact length of the wire pairs inside a cable. One can be interested in calculating voltage drop or some other calculation regarding the exact length.
Because the ...
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Microstrip Voltage Boundary Condition
I was reading some notes about a microstrip line. Here the scheme with the reference system:
In this scheme (sorry for the bad quality of the picture) the upper strip is represented as a charge sheet ...
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Voltage at the load in matched transmission line
We have a source (Z_s) and load (Z_load) connected with a transmission line. It is known that the connection is matched, that means Z_s=Z_0 and Z_0=Z_load. If the voltage from source is 1V, what will ...
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Derivation of telegrapher's equations
I'm currently going over the derivation of the telegrapher's equations shown here, but there's a step that I'm not fully grasping.
I think I can follow some of how you get from eq.3 to eq.5:
If the ...
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Impedance Matching Long 2000 meter Transmission Line
My apologies if this isn't the most appropriate forum to ask this question, but I have found the response from users on this form to be extremely helpful in the past with my electrical questions.
I ...
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Ringing problems on the output of inverter/comparator
I'm trying to drive some RF switches that need 0 to -5 V control logic with a 0 to 3.3 V signal. I found 2 topologies for this level shifting effect, one using a comparator and one using an inverter. ...
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How to estimate characteristic impedance for a random cable and tolerance of the termination resistor?
When we have a source with 50 Ohm output impedance we use a coaxial cable with a 50 Ohm characteristic impedance. And if we don’t know the output impedance then we use a 50 Ohm termination resistor at ...
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Broadband planer Magic-T design verification
There is magic tee topology described in the paper “A Broadband Planer Magic-T using Microstrip-slotline Transitions”. The response of model shown in figure 3 (see page 3) differs from those shown in ...
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IEEE test system accuracy and transmission line connections
In practice, do transmission lines ever directly connect two electrical generators to each other? Or is it more common for two generators to be connected indirectly through a substation? In the IEEE ...
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Is current direction always opposing when signals are reflected on a transmission line
Having read Dave Tweeds excellent description of reflections in electrical transmission lines, I thought I was one step closer to a full understanding of SWR. However, later I was watching w2aew's ...
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Pulse Down a line with Series terminations between transmission lines
I am interested in a relative edge case in transmission line of a simulation.
If send a pulse down the setup below, now obviously my rudimentary steady state electronics knows this is a basic voltage ...
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Time Domain Reflectometry and reflection coefficient graph
I know it is possible to see if there is a mismatch on a certain device (for instance a transmission line of length L connected to a load) by using the TDR (Time Domain Reflectometer).
It allows to ...
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Transmission Line Mismatch Simulation
I found an interesting simulator for transmission Lines. I can set a precise value for the load and then see what happens. For instance, let's suppose Z0 = 50 Ohm and let's consider these cases:
1) (...
