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.
Questions tagged [transmission-line]
814 questions
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Why weights on cables between utility poles?
Yesterday I saw what look like weights hanging from a cable between utility poles. This was in northeast Arizona on Route 60 between Show Low and Springerville. Here is a picture of a whole span:
The white blobs are the weights. Here is a…
Olin Lathrop
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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 ?
Electrical Engineer
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What is wrong with my 50 Ω grounded coplanar waveguide?
I've been working on a 4-layer design built around the EFR32BG13 Bluetooth Low Energy SoC. While trying to measure the impedance of the antenna to build a matching circuit, I discovered that my short grounded coplanar waveguide (GCPW) transmission…
Michael Cooper
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How do transposition towers in transmission lines work?
There're such things as transposition towers in power distribution powerlines. The idea is that for example you have three conductors running in parallel at the same height and the leftmost of them is phase A and after transposition the middle one…
sharptooth
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If we could start our electrical grid from scratch with today's technology, which would be the most efficient choice? AC or DC?
Lately, I’ve been reading about the many advantages of HVDC transmission systems for long distance transmission, undersea links, and others. The historical reason of why AC was picked over DC was mostly due to the invention of the transformer, which…
Jota
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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?
user43153
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Transmission line reflection. I would like a non-mathematical explanation
I am a licensed radio amateur, and find bewildering the many different explanations, which range from folksy urban myth to Maxwell-Heaviside Equations, of what happens at the termination of a transmission line or feeder. I realise that they all come…
Harry Weston
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What happens at the end of a transmission line?
Let's say I wanted to make a widget containing a relay to switch between two antennas. There is a coax transmission line coming in from the transmitter, and two going out, each to a separate antenna. Inside is a relay which switches the center…
Phil Frost
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Why not implement 1Gbps, when all I need is 20Mbps?
Background
I am working with a client on a large project which requires a custom networking chip to be designed to solve the data transfer requirements within the project. The network is intended to send small packets a few inches from one PCB to…
Rocketmagnet
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Why must some HDMI repeaters know the cable length?
I just bought an HDMI repeater and had connectivity issues until I realized the repeater had to know the cable length. It has (1,2,4,8) dip switches that you have to use (binary coded) to set the cable length.
What I'm wondering is: How is the cable…
Jeffrey
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What is this device attached to a high-voltage power line?
I noticed this white, cylindrical device on a power pole near Seattle that facilitates a 90-degree turn of the transmission line. It looks like the lightning conductor comes down the pole into a sort of service loop before disappearing into the…
Peter Schilling
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Why not use a ferrite bead around an RS-232 cable?
This is from the instruction manual of a printer:
As you can see, one is not supposed to wrap the supplied bead around the serial cable. What is the reason for this?
AndreKR
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What's the importance of source impedance termination?
Given a circuit like this:
simulate this circuit – Schematic created using CircuitLab
What's the importance of R1? One can guess that it's to make the output impedance of BUF1 equal to the impedance of the transmission line, but why is this…
Phil Frost
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What are these teardrop-shaped loops in power lines for?
I just happened to notice this along a road near where I live:
So these were in a pair, oppositely facing, "tip" to "tip" of the teardrop.
At first glance, this doesn't seem to be a bird diverter like here.
What is it for?
Note - I wrote "power…
StayOnTarget
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Physics behind signal reflections and series termination
I have been looking for cause of signal reflections in transmission lines. Everywhere it is concluded that the reason is impedance mismatch. I can understand if the impedance changes in the path of the signal travels, then reflection will occur, but…
Vignesh C
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