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 ...

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915 views

Does current flow on an open transmission line?

Please take a moment to look at the diagram below: The question is if the lightbulb will momentarily flash when the switch is closed. I think it will but I get the feeling I am wrong. The reason ...
1
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1answer
46 views

Confused regarding standing waves on transmission line

I am currently learning about transmission lines form an online book hosted by a website called “All About Circuits”. If anyone is interested, the particular chapter I am currently reading can be ...
2
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1answer
73 views

Very odd open-drain output design

I ran across a open-drain design and am baffled by the resistor between the nFET source and ground. There are only two purposes that I see it could serve. 1) It's series source termination, matching ...
2
votes
3answers
63 views

Back reflections at low frequency?

Say I have a signal driver operating at 50 ohm output impedance, driving something with high (hundred kilo-ohm) input impedance. If the wavelength I'm using (a few kilohertz) is much longer than my ...
42
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1answer
3k views

What is this object found on transmission lines?

What are the components, circled in red in the figure, on this transmission line ?
2
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1answer
30 views

Measure propagation velocity through finite transmission line

I'm currently trying generate a wave in a circuit but am running into the issue of figuring out exactly how to measure the propagation velocity. The circuit diagram is below L1=L2=L3, C1=C2=C3, ...
6
votes
2answers
122 views

Intuitive explanation of Skin Effect?

I'm trying to wrap my head round Skin Depth, we've derived the wave equation from Maxwell's equations, using the conditions that it's a "good conductor" ρ = 0, σ >> ωε and ...
0
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1answer
66 views

what is the Input impedance of transmission line, when source frequency contains two frequency components?

what is the Input impedance of transmission line, when source frequency contains two frequency components? I know the expression of input impedance of a TL, but it assumes that only a single ...
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1answer
59 views

Reading a resolver sensor with a long cable

I am trying to read a resolver sensor attached to a stepper motor through a long cable (500 meters). More specifically with a resolver to digital converter. However I get an error respect to the ...
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0answers
35 views

Shielding of magnetic flux with copper plate

Where in the copper plate do the eddy currents lie, and what are their phases, relative to the source current? Does this phase vary with frequency? 1) As far as i know the eddy currents will be on ...
0
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1answer
44 views

Guidelines for twist cables

Which are the guidelines for chose which cables should I twist as a pair? For example, suppose the case in which I have 3 cables. One of Vcc, one of GND and another of signal. Which ones should I ...
2
votes
2answers
99 views

Role of “HDMI Baluns”?

I understand that an HDMI cable contains essentially 4 shielded twisted pairs, along with additional control lines. Each of the twisted pairs is specified, to my understanding, to be a balanced ...
2
votes
1answer
60 views

Voltage on coaxial line - calculation process

Compute the voltage on the end of coaxial line (\$Z_0=75~\Omega\$, \$l=100~m\$,\$\tau=5~ns/m\$) at time \$t=1.6~\mu s\$ after connecting the line to voltage source (\$U_0=6~V\$,\$R_i=0~\Omega\$), if ...
0
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2answers
27 views

How is the capacity of link more for single network link

In networks capacity_of_link = bandwidth*propagation_delay My doubt is how can a same wire carry multiple signals? Is is because the wire is very long (still the wire can be either high or low). I ...
4
votes
1answer
163 views

Impedance matching with only capacitors?

I need to do impedance matching for 33 + j32 ohm source and 16.5 + j0 ohm load. The copper traces adds 99 ohm impedance and 20 degree electrical length. According to smith Chart below, I need to use ...
3
votes
2answers
105 views

Which of these Stripline Impedance Calculations is correct?

Different sources are giving me drastically different characteristic impedance values, and am hoping someone will verify them for me. Generally, with microstrip, I start with an online calculator to ...
11
votes
1answer
288 views

Balun/matching network question

I am having problem to verify what an app note (AN068) explains to calculate Balun values. I would appreciate if someone could tell me what/where am I doing wrong? The summary of the RF part: Blue ...
4
votes
2answers
146 views

Transmission Line Impedance Matching Basics

From what I understand, matching a load to a transmission line means that no signal is reflected from the load, which means that at the two sides of the connection point between the load and the ...
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vote
1answer
52 views

How is the voltage and current plot for a matched transmission line constant?

When the transmission line is terminated with a matched load the voltage on the line is given by V(z)=E e^(jβz). where β is the phase constant of the line. 1)How is the voltage plot a constant for ...
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1answer
64 views

How to picture sinusioidal wave in transmission line(electrical circuit in general) ?

I have a friend who keeps asking how does a sine wave flow in transmission line. I've tried explaning him that it is the folw of charges in either directions but he isn't convinced yet . Can somebody ...
2
votes
4answers
146 views

Why do transmission line equations use current through inductor rather than capacitor?

I could not fit the title in I actually wanted which was this: In the transmission line equations why is the current difference either side of the inductor used in the capacitative current drop ...
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1answer
51 views

Power management at thermal power station

I have weird question, but I hope somebody can give at least hint what should I read to understand the concept. Imagine situation: There is thermal power station and a city that takes power from ...
1
vote
2answers
97 views

Waveguides: How can you propagate at only one frequency?

In a rectangular waveguide, we know we can find cut off frequency as a function of mode and geometry. Is there a way to design the waveguide so to ensure that we can limit the frequency of ...
0
votes
1answer
96 views

coplanar transmission line on both sides of a four layer board

I am designing a four layer board in which i have to run two 50 ohm traces one at the top and other at the bottom side of the board. I have decided to use Coplanar wave guide for both the traces. I am ...
3
votes
2answers
172 views

TTL Long Distance Transmission Alternatives

I am working on a system that gets data from a sensor via a TTL connection. Currently, the data that is gathered from the sensor is sent to another part of the system via a set of modems. The ...
2
votes
0answers
69 views

TV antenna problem: Transmission line problem

I have to solve the following problem: A TV antenna lead-in wire 10cm long has a characteristic impedance of 250 \$\Omega\$ and is open-circuited at its end. If the line operates at 400 MHz, determine ...
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0answers
42 views

Voltages in a transmission line network

I have been using S parameters (and T parameters) to understand the behaviour of transmission lines with inline components, and this has worked very well. Is there a way to use or extend this method ...
2
votes
2answers
118 views

Very long transmission-line design tips

I'm designing a very long transmission line between a master node a some slaves far away connected by a bus where only 3 wires are used: - A DC power supply (24vdc) - B Digital comm - C Ground As ...
0
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1answer
158 views

Sending Signals over a Coaxial Cable [closed]

Recently I've been trying to understand how multiple signals can travel along a coax cable. Indeed, I have already read "How are multiple signals propagated in a coaxial cable?", but it doesn't seem ...
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2answers
65 views

How does the circuit fill up?

I came to know that in transmission line if I send only the phase to the houses and make the neutrals to ground then the circuit works. How does the circuit fill up without having any closed contact ...
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0answers
85 views

How long of a wire and how big of a load can I have for SPI bus?

I have a system where I will connect up to 128 identical magnometer ICs up to an FPGA. I am trying to decide between SPI and I2C for comms. If I use SPI the setup will require 128 + 3 wires IF all ...
2
votes
4answers
166 views

Do transmission lines induce electric or magnetic fields in towers?

Transmission lines have EM fields around them due to the high amount of current. Do these fields affect transmission towers (metal or otherwise)? If so, would it be possible to estimate the current ...
1
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1answer
57 views

How does the impedance that voltage “sees” while traveling down a tranmission line affect how the current move down the line?

It is well known that the voltage sees different impedances while traveling down a tramission line, and this impedance is a function of the intrinsic impedance of the line Zo and tangent of wave ...
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2answers
192 views

What is actually transformed in quarter wave transformer?

I'm reviewing some stuff on quarter wave transformer for a transmission line but since I have not had any experienced in handling these type of stuff, I am struggling to understand this concept ...
0
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1answer
90 views

Impedance line matching and component value matching

I have the following circuit for the SIM900's antenna connection, using the A10393 antenna from digikey: In closer look: First of all my knowledge on RF design is not great. My questions now are ...
2
votes
2answers
147 views

When a voltage pulse is sent through an open transmission line, what happens to the voltage at the end of the line when the pulse is reflected?

From what I understand, the voltage doubles since the reflected and incident pulses add up. But then why don't all open terminations have double the source voltage since we can consider the voltage ...
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2answers
158 views

Using attenuators to damp reflections on transmission line?

I have a 3m long transmission line that transmits a 100ns bipolar square pulse every 200us. At the beginning of the coax cable is a pulsing circuit board, that generates the waveform, then it sends ...
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3answers
126 views

Simulate RF transmission lines at Low frequencies

I would like to simulate RF transmission lines in how they propagate, and how impedance mismatches at the end of the transmission line cause reflections and power transfer does not work. It would be ...
0
votes
2answers
82 views

Why is the data rate a function of the length of the transmission line?

The length of a transmission line is limiting the highest possible data rate on that line. Why are faster signals more likely to become corrupted on long transmission lines than on shorter ones, with ...
9
votes
3answers
316 views

PCB RF Layout Critique: Input on my radio-telescope PCB

I'm attempting to do the board layout for a radio-telescope we're building at one of my jobs. Here is the overall system topology: QRFH is for "Quad Ridged Feed Horn". It's a rather esoteric ...
2
votes
2answers
66 views

Why is there no voltage drop along a feedline

This page shows a graph of voltage along a transmission line by distance. Considering the case of a simple purely restive feedline of 50 ohms matched to a load of 50 ohms, I would expect the voltage ...
2
votes
1answer
110 views

Stripline reference plane discontinuity in reference design

According i.MX6 SMART DEVICE SYSTEM of freescale layout board, it uses 8 layers, my question is about the inner layers, they are striplines with a continuos GND plane in one side but in the other side ...
2
votes
3answers
774 views

Tapping energy from high voltage AC transmission lines

The details are hazy as I recollect this from my nipper days.Many, many years ago. “Persons were charged with stealing electricity by placing a large coil, somehow, near high voltage AC transmission ...
8
votes
8answers
530 views

Neophyte question about AC vs. DC (especially for powering a home)

Here in the United States the electricity grid is AC. I have heard that AC allows transmission of power at greater distances with less loss. However, with the advent of solar panels, it would seem ...
0
votes
1answer
630 views

Coplanar waveguide for differential trace calculator

Although there are plenty of free impedance calculators out there, I'm struggling to find one that can solve impedances for a differential pair using coplanar waveguide. Anyone know of any free ...
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0answers
66 views

Impedance matching and calculating reactance

Design a reactive L network in order to provide impedance matching between transmission line of \$Z_o = 300 + j60\$ and an antenna having impedance of \$80 +j100\$ at the frequency of 1MHz. How ...
0
votes
1answer
38 views

How to find attenuation constant

Propagation constant is in the form P= a+jb (a= attenuation constant b = phase constant) a +jb = ln (x+ jy). How do I separate the real and imaginary part in the RHS so that I can equate the ...
5
votes
3answers
8k views

Why does the USA use 110V and UK use 230-240V?

Why does the USA use 110V and UK use 230-240V? What are the advantages? Explain me with calculation. Why do they use different frequencies like 50Hz, 60Hz? What is the reason?
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2answers
148 views

Best way to drive long signal cables

What is the best way to transmit analog signals between 100 Hz and 100 kHz over a distance of up to 6000 m with minimum frequency depending loss, the level is 50 uV to max 1V (always less than 100 mV ...
3
votes
2answers
97 views

Finite parallel impedance network general solution

Does anyone know if a finite number of parallel-series impedance has a general solution? I am trying to model a network flow problem that can be described in electrical terms and represented as a ...