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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71 views

The mathematics of saltatory neuronal action potential transmission [closed]

Some time ago, I tried to understand saltatory electrical potential transmission on a myelinated axon but have not found a clear mathematical model of this mechanism. The neuronal signal ...
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1answer
40 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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46 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 ...
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1answer
25 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 ...
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3answers
309 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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97 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 ...
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58 views

Good book/reference for electromagnetism and distributed elements model

I am looking for a good explanation of what is in "between" of Maxwell's equations and the lumped model. I am talking specifically of RF electronics and the distributed elements model. I am ...
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2answers
73 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 ...
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39 views

What are quarter-wavelength conditions for transmission lines?

For a transmission line consisting of three segments in series (of equal length and outer conductor diameter but different inner conductor diameters) the impedances must be matched following ...
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2answers
87 views

Finding exact breakpoint location in long wire

How can I find the exact location of breakpoint in my long transmission line? Please help with the methods.
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3answers
72 views

Conductance in a transmission line

I'm just trying to clarify the transmission line concepts in my head. Now wikipedia (that great source of always reliable information) defines the conductance in the transmission line as ...
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1answer
111 views

RF Circuit (what does capacitor do?)

I'm trying to work out why a 0.7pF capacitor was chosen. The circuit operates at 12GHz. At 12GHz, the capacitor has an impedance of about \$18\Omega\$. Also at 12GHz, ...
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1answer
34 views

CML signal to ground terminated line or peak sensing ADC for short pulse

I'm currently designing the prototype of a timing instrument. One sensor gives an analog CML (current-mode logic) signal, from an amplifier (ADN2880). One end of the pair is routed to a comparator ...
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2answers
194 views

Why does more bandwidth mean higher bit rate in digital transmission?

I understand that similar questions like this one have been asked before on this site, listed below. However, I am confused about the answers. If I explain what I think I understand, can somebody ...
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2answers
140 views

Minimal distortion in transmission line

In a transmission line, the condition for minimal distortion (caused by the line) are when (R/L = G/C) in the line, right? However, I don't see any reference to that in any application notes or ...
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1answer
117 views

1/4 wavelength case in transmission lines

I have studied that in transmission lines, if λ is the wavelength of the signal and L is the length of the conductor, then at L=λ/4 the transmission line act as an open circuit. So if we are ...
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1answer
81 views

Designing RJ45 connector to have 100Ω differential impedance

I'm designing two pairs of connectors that have same layout as RJ45 (just 2 inner pins) to have 100 ohm impedance deferentially. Are there tools that allow to calculate impedance or ...
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1answer
65 views

Radio antenna isolating transformer

I need to isolate galvanically my antenna from my RF transceiver. For this I have been recommended a transformer, I select a 1:1 transformer operating in high frequency range. Is it enough to wire it ...
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0answers
219 views

Plotting reflection coefficient magnitude vs frequency in MATLAB

I am trying to plot a function (t) with respect to w in MATLAB. However, the output that I am seeing is showing 0 for all w within the defined range. This is not what I am supposed to be seeing. The ...
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0answers
55 views

Circuit that behaves as a long transmission line. Any ideas? [duplicate]

I am in need of a circuit that would replicate the behavior of a very long coax cable (miles long). Namely, I am interested in how it would distort a relatively low-frequency signal and how it would ...
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0answers
36 views

Applying Transmission Line Theory To Plane Waves

I'm working on a project for my E&M class. Our goal is to use transmission line theory to design a "stealth" dielectric layer for some sort of aircraft. I can assume the radar wave is incident ...
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71 views

Can we draw analogy between em power flow through free space and ac power flow through a transmission line?

Knowing that the free space has a characteristic impedance (which is purely resistive, measured in ohms) I was wondering if I can model the free space as an infinitely long transmission line- ...
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1answer
145 views

What determines what type of short-circuit current is highest?

I'm doing a short-circuit analysis of a system, and started wondering about the following: What determines which type of fault current is the highest (and lowest)? The screenshot below shows the ...
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2answers
159 views

A transmission line with continuously varying impedance, how would reflection occur in this case?

Alright folks here it is, another transmission line question that has been bothering me. I understand the case where there is an abrupt change in impedance along a transmission line that leads to ...
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1answer
339 views

Derivation of Characteristic Impedance?

I start from the telegrapher's equation: \$-\frac{dV(z)}{dz}=(R'+j\omega L')I(z)\$, where \$V(z)\$ and \$I(z)\$ are the phasors of voltage and current respectively, in the transmission line model. ...
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1answer
507 views

Why does reflection off a PCB via look like this?

My question is related to http://mobius-semiconductor.com/whitepapers/ISSCC_2003_SerialBackplaneTXVRs.pdf. On the page 18 there are a few figures of "TDR off Diferent Types off Vias". I am confused ...
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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 ...
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1answer
244 views

Does forcing a data line to a higher power make it more resistant to interference?

A device I'm working on as a hobby project requires me to transmit a HDMI signal over cat5. The TMDS lines in HDMI are balanced but in order for me to continue transmitting the DDC signal with the ...
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1answer
77 views

Regarding Transmission line

Is every wire a transmission line or a transmission line has a special manufacturing process? But why during analysis of normal electrical circuits we never consider parameters like characteric ...
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1answer
215 views

How short can an RF transmission line be?

Design for connecting transmitters to antennas often mentions the transmission line, and the standing wave ratio (SWR) for matching. But what if the transmitter is on the antenna? Background: I've ...
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2answers
217 views

Why a wave does not enter a cable? Understanding TDR (Time Domain Reflectometry)

I have been doing some TDR (Time Domain Reflectometry) measures which involves sending gaussian pulses through a cable and measuring the s11 (reflection) parameter. In this measure, I could see that ...
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1answer
51 views

Calculate balance between signal and noise to allow 32 kbit/s transfer

I have to calculate proper balance/ratio between signal and noise ( S/N ) in decibels ( dB ), to be able to transfer data over the channel at 32 kbit/s. Channels bandwidth is 100 kHz. I was given ...
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1answer
41 views

Calculate transmitting power of the Transmitter

I cannot get a hold of my professor and I'm stuck tyring to understand how to solve this problem. It's not homework or an assignment I'm preparing my self for a test. So as the title states I need ...
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3answers
211 views

Amplify .7Vpp square wave to 5Vpp square wave buffered to go over a 15-50 foot cable

I've got a sensor that outputs a .7Vpp square wave at 36kHz-60kHz. I need to take that square wave and amplify it to 5Vpp, as close to 0V to 5V rails as possible. Then I need to send that signal ...
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2answers
160 views

terminated cable capacitance

As much as I know, the input impedance of a coaxial cable with a characteristic impedance of 50 \$\Omega\$ which is terminated with a 50 \$\Omega\$ load resistor, should be 50 \$\Omega\$ as well. This ...
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134 views

Calculating reflections

I just solved a problem in my homework. I had to calculate the reflection waves and I was given the following data: // Resistance R0 = 120 Ω line impedance Ri = 90 Ω resistance at input Rb = 1 ...
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1answer
147 views

Confusion regarding considering a transmission line as lumped or distributed

I am just elaborating my question. I have came across different formula's to say whether a Transmission line is lumped or distributed. in one of the books i read " Effective length of a electrical ...
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3answers
162 views

understanding transmission line signal integrity through simulations

I need to simulate how signals are reflected based on the source, load and line impedances and how the signal integrity is effected by the spacing between different traces on a board, traces on the ...
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1answer
183 views

Do long transmission lines degrade rise/fall times, and if so, by what mechanism?

I remember someone telling me long ago that if a voltage step is sent down a transmission line, the step will become smeared as it travels down the line, and the rise time will become degraded. I'm ...
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2answers
163 views

Does the noise figure of a cable change if the load/source is mismatched?

I know that the noise figure of a transmission line is equal to its attenuation (usually expressed as dB/m or dB/100 ft). However, what if there is a mismatch between the line's characteristic ...
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1answer
584 views

How do different methods of transmission line termination compare?

It seems to me that there are three ways to terminate a transmission line: at both ends at the load only at the source only simulate this circuit – Schematic created using CircuitLab ...
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2answers
616 views

What is the purpose of the thin wire at the top of power transmission lines?

I know a power transmission line carries usually two sets of 3 phase conductors. But I have noticed a relatively thin wire at the center-top of the power transmission line. What is the purpose of this ...
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3answers
274 views

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 ...
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3answers
680 views

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. ...
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5answers
884 views

Can we measure reflected power in a transmission line?

This is a question related to radio transmission, I hope this is the proper forum to ask it. It relates to transmission lines connecting a radio transmitter to its antenna. In his book "Reflections", ...
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2answers
184 views

How does less cable impedance, source/termination impedance, lead to longer cable length for higher data rates?

This question is about high speed digital transmission on a transmission line, I need to know about how does the (1) impedance of the transmission line and the (2) source impedance and (3) ...
28
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2answers
739 views

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 ...
19
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3answers
478 views

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 ...
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1answer
321 views

Cable Splitter Loss and Impedance Matching

From my memory, cable splitters (such as for splitting a cable tv coax cable into two televisions) provide impedance matching to prevent signal reflections, etc. If one 50 Ohm line is split into two ...
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1answer
298 views

What is a good tolerance for impedance matching or how to calculate losses?

If you build a microstrip on a silcon wafer, connected by picoprobes via SMA connector and cables to a VNA, what is actually a good match of the impedances of the cables and the waveguide. Is there a ...