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.

Filter by
Sorted by
Tagged with
1
vote
1answer
35 views

“The D-PHY specification defines the maximum lane flight time to 2 ns.” Why?

I'm hoping someone can explain to me why the maximum lane flight time matters. Impedance matching, skew, attenuation, etc. all make sense to me as a natural limitation to how long an interconnect can ...
1
vote
0answers
36 views

Voltage regulation at full load

The voltage regulation is I(Rcosa -Xsina)/Vr For leading pf Here %of regulation=(VRcosa-Vxsina)/Vr ×100 %=((4×0.8)-(6×0.6))/100 ×100% =-0.4 Where I am doing wrong?
0
votes
3answers
85 views

Why does the length of the wire matter to the value of the pull up resistors?

In this DHT-11 datasheet the following sentence was mentioned (on page 4) A typical application circuit recommended cable length shorter than 20 meters with a 5.1K pull-up resistor when greater than ...
3
votes
3answers
144 views

How far can radio signal be transmitted through a straight steel pipe?

We are needing to transmit data between a robot that will be traversing a pipe, and a base station located at the end of the pipe. The pipe is about 2 feet in diameter, made of steel, and is ...
2
votes
2answers
138 views

Please help me solve the below Directional coupler problem

I have tried and my answer keep coming 0db.I am not sure this answer is right as this is only kind of problem I have seen where port is short circuited.
1
vote
1answer
50 views

how do you model a transmission line at dc?

how do you model a transmission line at dc?
14
votes
2answers
1k views

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 ...
2
votes
1answer
34 views

Crosstalk between transmission lines

I was reading these slides about crosstalk between transmission lines. At page 6 there is this circuital model to describe the effect of mutual coupling between these two lines: My doubt is: why \$I_{...
0
votes
1answer
89 views

Impedance of a lossless line

I am currently looking for a term for a lossless line with a wave resistance Zw which is open ended and I am not sure if I have calculated correctly. My thoughts about the calculation: If the line is ...
0
votes
1answer
37 views

Multiple differential tranceivers on single bus

Im using a few moduls of rs422 tranceivers connected on single bus Easy module has transciver with TX input, RX output power end differential pair output and input - but no EN pin to hold the ...
2
votes
1answer
69 views

Meaning of reflection coefficient in English

So I know a reflection coefficient of 0.5 angle 30 at the load (k=0m) means "At this point, 50% of the incident wave is reflected and has a 30 degree phase shift." But what does it mean in ...
2
votes
3answers
63 views

Why does reflection coefficient phase depend on position along a T line?

I'm in an intro electromagnetics class. It makes sense to me that reflection coefficient at the load has an imaginary component, because I am thinking of it like "the reflected wave is some ...
1
vote
1answer
57 views

3.3V TTL to other formats and impedance matching [closed]

I am trying to convert a 3.3V 50 Ohm Impedance TTL Pulse-per-second into other formats (GPIB, USB, RS-232, etc.). I've found some format adapters/convertors like the MAX232, but I am either ...
2
votes
5answers
114 views

Is there a difference between PCB trace impedance and transmission line characteristic impedance?

PCB trace impedance (equations) don't seem to take into account frequency, I have (previously) been considering this to be a characteristic impedance i.e the distributed impedance of the line 'viewed' ...
0
votes
3answers
92 views

How we can possibly transfer a USART signal(3.3v) over 12 meter cable without any driver?

I have two atmega328p boards working at 3.3v. First boards read a sensor value and send it to the second board through the USART. The two boards have 12 meter distance. The two boards are connected by ...
1
vote
2answers
192 views

CAN Bus on PCB traces instead of twisted pair cable - points to consider

In order to save cost on the system in one of my current projects (no cables) I would like to eliminate the CAN cable and add traces to the PCB (one pair from left to right to connect the connectors + ...
4
votes
1answer
68 views

how to understand unparalleled transmission line?

in a normal transmission line example, shown as case-1 in below picture, the signal path and return path are parallel to each other, let's say it takes 1ns for the signal propagate from left side to ...
1
vote
0answers
31 views

Open termination, signal propagation, transmission lines

I'm inexperienced with transmission line theory so I have a question about implications of signal travel time. Most of what I've read so far has been on lossless transmission lines, not sure how ...
0
votes
2answers
76 views

Oscilloscope amplitude reading depends on cable length? Reflection help

Suppose I have an RF source with 50 Ohm output impedance. First lets imagine the RF source outputs a low frequency 10 kHz signal (electrical wavelength is about 20 km). Suppose I have a 50 ohm coax ...
0
votes
1answer
56 views

Controlled impedance traces necessary between line driver and series termination resistor?

I'm designing a line driver circuit with the SN74BCT25244 chip. The chip has a rise time of ~10 ns into an open circuit based on my own scope testing, but we are only wanting to drive the signal at a ...
1
vote
2answers
36 views

CAN Bus Nominal Impedance

I understand the reason for choosing a termination resistor of 120 Ohms for the CAN bus to avoid reflections but why was the nominal impedance of the CAN bus cables required to be 120 Ohms by the ISO ...
3
votes
1answer
61 views

Decoupling capacitors on bottom layer in non-BGA packages?

Typical advice on decoupling techniques usually gives highest priority to: always place the decoupling capacitors on the top layer, next to the pins. BGAs of course are a separate issue; I'll come ...
0
votes
3answers
79 views

Does matching impedance connectors matter in non-RF signals? Why?

I am designing a PCB which communicates with an encoder over RS422 at 2Mbps (15ns rise time typical in the MAX490's datasheet), and I am currently selecting the connectors. I have found 120Ohm twisted ...
0
votes
1answer
47 views

Why do ICs interconnects have squared corners

I was wondering, why do ICs interconnects have squared corners if they carry hi-frequency signals? (considering most transmission lines that handle high speed signals have chamfered/beveled corners ...
0
votes
2answers
32 views

Series connection of transmission lines described by telegrapher's equations

My issue concern the definition of series connection of multiple transmission lines described by the so called constant parameter model, to be next simulated in EMTP-RV. Let us take as an example two ...
1
vote
0answers
45 views

Laplace vs Fourier Transforms in Transmission Lines

Consider an electric transmission line with transient equations $$\frac{\partial v}{\partial x} =-Ri -L\frac{\partial i}{\partial t}, \qquad \frac{\partial i}{\partial x} =-Gv -C\frac{\partial v}{\...
1
vote
1answer
30 views

Design guidelines for RF castellated edge connections

I've seen many examples online of castellated vias at board edges used for module connections. However, all of these seem to be for low frequency signals. When using a castellated via to connect an RF ...
3
votes
0answers
32 views

Can I calculate minimum rise time of a transmission line if I know the length and the loss tangent?

Overview: I am trying to work out if it's possible to transmit my 1.2Gbps MIPI data down a 600mm long flexible PCB strip. Assuming I have the impedance correct, will the signal still be degraded by ...
1
vote
1answer
124 views

Loading an FPGA pin at 20MHz in parallel

I'm designing a traction inverter controlled by the NI sbRIO-9627, which includes a Zynq-7020 FPGA. I am considering using a single FPGA pin to drive the external clocks of 14x ADuM7701 isolated ADCs ...
1
vote
2answers
44 views

Amplitude plot of voltage standing wave on a transmission line

edit: I just found a site almost perfectly describe the issue, https://ophysics.com/w3.html I found this graph on Google but couldn't find an explanation of it, it is similar to the one presented in ...
0
votes
0answers
45 views

Different results from Smith Chart and Transmission line impedance equation

I have the following question which I need to solve Use a short-circuited section of air-filled TEM, \$50\Omega\$ transmission line ( \$\beta= k_0 , \lambda_g = \lambda_0\$ ) to create an impedance ...
0
votes
0answers
62 views

Single wire earth return system

So, in a single wire transmission system, the earth acts as the return path for current to "flow back to source". Would this work for anywhere on earth, say, if we transmit current on a single wire ...
0
votes
2answers
55 views

Underwater communication trough cable

I wanted to build a device which can stay and move underwater (let's say, for instance, 15m underwater). Since RF frequencies are very attenuated by water and VLF antennas would be too high, I was ...
0
votes
0answers
33 views

Transmission line current magnitude

I want to compute the current magnitude in a transmission line. The line has properties b (total line charging susceptance, p.u.), ...
0
votes
1answer
40 views

ST ST25R95 - NFC chip - Impedance of transmission lines

I will supply the chip with 3.3V, and the datasheet of ST25R95 IC shows it has a ZOUT of 27R at this condition. There is a circuit between NFC antenna/coil/inductor and the IC, the LC filter and ...
0
votes
1answer
30 views

Couplers and dividers as baluns

Can every divider and coupler that provides 3dB amplitude divison and 180 degrees phase difference be used as balun? Rat race coupler and lange coupler provide the two conditions mentioned above. ...
0
votes
1answer
45 views

How to do via fencing of an RF trace with a 5V front copper plane and a GND back copper plane?

Background I am a building a board to send RTTY via a Radiometrix NTX2B as part of my final year High Altitude Balloon (HAB) project. I have just created a PCB which I uploaded to JLCPCB for ...
1
vote
1answer
72 views

What is happening, physically during a Transmission Line Reflection in a closed and open circuit scenario?

I am having trouble understanding what is happening physically during a transmission line reflection, in particular the short circuit and open circuit case. I understand that when when a transmission ...
3
votes
1answer
98 views

How can there be a zero sequence current in a single line to ground fault with an ungrounded neutral

The circuit that describes a single line to ground fault in a system with an ungrounded neutral is: I neglect capacitance between phases and only look at capacitance to ground. The definition of zero ...
2
votes
3answers
41 views

relation between transmission line & circuit impedance

What is the relation between the impedance of lumped components and the characteristic impedance of transmission lines? I have noticed that in some cases transmission lines are loaded with lumped ...
3
votes
4answers
141 views

How to demonstrate mathematically the conditions of reflection in transmission line?

We are all taught about transmission lines and its associates -- characteristic impedance, reflection, standing wave, etc. It is well known what happens when a transmission line is terminated with ...
1
vote
1answer
35 views

I have a hard time with determining the input impedance of the problem shown as well as the equivalent lumped circuit model with this Zin

This is the work I have done so far. I am not confident in my work and was having a hard time with determining the input impedance. If you have a correction or opinion on this work please comment.
0
votes
0answers
11 views

Multi Driver EJTAG interface routing considerations for better SI

we have a MIPS uP which has EJTAG interface. This needs to programmed from Both P1(by default) & P2 connectors This EJTAG interface needs to be shared between 3 drivers. Assembly Option1 in ...
1
vote
1answer
56 views

Can these S-parameters be derived?

I have been trying to derive the S-parameters of a lossless T-junction of transmission lines. Here's a diagram from Google: This is an exercise in microwave network analysis, not in design, so the ...
11
votes
5answers
3k views

Signal velocity in PCB traces

On what does the signal velocity depend for a signal traveling through a PCB trace? According to Wikipedia, it depends exclusively on the relative permittivity (ε_r) of the medium (well, it also ...
2
votes
3answers
1k views

Why single ended signal line is not immune to noise in RS232?

In single ended signal line the measurement is the difference between the signal and the ground. Isn't this way of calculation make it differential? Almost all the resource I have read says that ...
2
votes
1answer
139 views

Difference between single circuit and double circuit transmission line protection systems

I'm doing a research on long three phase transmission line protection systems and I found many schemes such as distance protection, merz-price voltage balance system, split-conductor, "translay" ...
1
vote
1answer
38 views

Understanding series open stub tuning

I recently had an assignment where I had to use open stub series tuning to find a way to maximize power delivered to the load from the generator. I understand that power delivered to the load is ...
0
votes
2answers
48 views

Length-matching microwave differential traces

I'm driving an RF mixer that takes differential input signals. My max signal frequency is \$6\,\text{GHz}\$. I understand that the differential input signals need to be length-matched, but what sort ...
0
votes
2answers
29 views

In a transmission line, does the real current interact with reactive impedances?

simulate this circuit – Schematic created using CircuitLab According to the diagram above, if real currents do not interact with reactive impedances, then reactive loads should not worry the ...

1
2 3 4 5
12