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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transmission lines voltage drop

When trying to explain the need for high voltage in transmission lines, I came across a formula in one of my old courses: A transmission line is considered, and between the generator end and the load ...
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41 views

How do I learn to design a 50Ω coaxial interconnection/interface? [on hold]

I've designed an electronic load for testing power supplies (circuit and photo in this post: Designing a *linear* MOSFET driver stage). The load can be controlled (programmed) using an arbitrary ...
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44 views

Tranmission line equations when initial conditions are not zero

A high voltage DC line is in steady state sufficiently long time after applying 1 MV at the input terminals through a DC voltage source of 30 ohm impedance with an open circuit at the load end. The ...
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Building a distributed low-pass filter with cutoff frequency of 1hz but the highest frequency of 10^13 hz

How does one build a distributed low-pass filter with cutoff frequency of 1hz and highest frequency of 10^13hz (or arbitrarily high)? In case of lumped circuits, this is easy to do, but in case of ...
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Cell phone bluetooth range

I've got this phone I'm doing some range testing with...Namely, a Samsung S5 with the latest firmware and I'm testing the WLAN/Bluetooth radio. This phone has unbelievable range...but, when I replace ...
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35 views

Where to Measure S11 with a VNA

I have someone else's design that I have been asked to choose matching components for. The antenna is a chip antenna and the filter is a band pass SAW filter in a single package. The SAW filter is ...
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484 views

Why does reflection only applies to transmission lines?

Why does the concept of wave reflection seem to only apply to transmission lines? For example, for a simple circuit with two resistances R1 = 50\$\Omega\$ and R2 = 75\$\Omega\$, is the voltage wave ...
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53 views

Mulitple open-circuit transmission lines

I'm using a single SPI microcontroller to talk to about 10 boards. Of course, only one of them is actively listening at a time, using chip select (for the unfamiliar, when chip select is high, the SPI ...
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26 views

antenna matching with lumped elements

Is there any resources online that describe how to match antenna elements to a TX line with a lumped element matching network? I've got a 50 ohm load and a TX line that i'm trying to match to a ...
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60 views

Can I tell the voltage of High Power Transmission lines by its Type?

I am moving to Foster City, CA and am looking at an apartment about 550 feet from these power lines: ...
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52 views

S11 all on the outside of the Smith Chart

How should someone conclude what's going on on a TX line that has a Smith Chart that goes around and around the outside? I've reworked a board and expected to see a curve pass close to (0,0), but what ...
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65 views

Shunt capacitor as discontinuity in transmission line

As in the following circuit simulate this circuit – Schematic created using CircuitLab suppose that an infinite transmission line (with characteristic impedance \$ Z_0 \$) ends upon a ...
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30 views

Calculating DC resistance from p.u. impedance

I need to calculate or approximate the DC resistance of a 208.5 km overhead line which has the following information: impedance per unit on 100 MVA base: R = 0.004 X = 0.047 B = 1.049 Is it even ...
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158 views

Transmission line: Why do longer traces cause signal reflections?

As the question says, I want to know why do longer traces/longer lengths of non-terminated signals of the PCB cause reflections and not the short length ones? I am ignoring the negligible amount of ...
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61 views

How to make proper copper trace transmission line calculations using wCalc?

Oli Glaser gave a fantastic answer to a question regarding termination resistors: Termination resistors: are they needed? I am trying to replicate his wCalc and SPICE simulation calculations for ...
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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 ...
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57 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 ...
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1answer
79 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 ...
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3answers
74 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 ...
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What is this object found on transmission lines?

What are the components, circled in red in the figure, on this transmission line ?
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44 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, ...
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159 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 ...
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73 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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78 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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64 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 ...
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110 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 ...
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63 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 ...
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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 ...
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181 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 ...
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145 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 ...
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367 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 ...
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160 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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67 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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65 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 ...
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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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54 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 ...
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106 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 ...
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131 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 ...
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218 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 ...
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79 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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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 ...
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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 ...
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223 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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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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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 ...
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4answers
204 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 ...
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63 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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233 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 ...
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118 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 ...
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166 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 ...