Questions tagged [reflection]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
2
votes
2answers
67 views

Questions about RF ground plane and low frequency reflections

Why do RF signals on a microstrip/stripline require a ground plane to propagate within a circuit? When studying DC and low frequency AC circuits in school, it appears that ground is a particular point ...
0
votes
1answer
26 views

Are multiple reflections accounted for in S-parameters?

When the S-parameters of a 2-port device whose input and output impedance are different from 50 Ohm are calculated/measured in a 50-Ohm system, multiple reflections occur at port 1 and port 2. Let's ...
2
votes
1answer
93 views

Parallel transmision lines reflection at the source

Question: There's a 9 V battery with output resistance of 50 Ω, at time t = 0 it is connected to two lossless transmission lines connected in parallel: LTx1 and LTx2. Both lines are identical, with ...
0
votes
2answers
63 views

How to find Z impedance if I have only S11 (db) and phase

I need to measure Z line impedance. Using VNA I measured S11 it is -53.8785 dB and phase at this point is 175.6706. Could you explain using these numbers how to find R and jR S11 = (Zx-Z0)/(Zx+z0) = -...
1
vote
1answer
53 views

Reflection coefficient in a microwave amplifier

I have a question about the reflection coefficient in a microwave amplifier (two-port network), what is it and what is it based on?
-1
votes
2answers
46 views

How reflection occuring in antenna fed by transmission line affects performance?

Transmission line considered is lossless. Basically the configuration is simple. For transmitter side : a non ideal source (can be voltage current or power) feeding a transmission line (TL1) with ...
1
vote
1answer
66 views

Could a time-domain reflectometer, with no access to earth-ground, indicate if a long-wire is attached to the end of a long steel beam?

Without using any other wiring, optics, RF, sound, or vibration, I need to know if a 100 meter length of electrical wire is attached to the end of a 50 meter long steel beam. I only have physical ...
1
vote
0answers
50 views

Typical power reflected off wall/window/wooden shelves etc

For interference purposes, I would like to quantify how much signal power I would receive back when my transmitted signal is reflected off an object (a wall, glass window, wooden shelf) at a distance ...
0
votes
1answer
30 views

Do surface charges exist when EM wave gets reflected by dielectric boundary?

If both the materials on a boundary are dielectric then do surface charge exists. I was solving using pillbox it showed that there should be surface charge on boundary to satisfy change in normal ...
0
votes
1answer
38 views

Refractive index, wavenumber, and wave impedance of the PEC that a plane wave is normally incident on

I am trying to find the refractive index \$n_t\$, wavenumber \$k_t\$, and wave impedance \$\eta_t\$ of a perfect electric conducting medium t. Here is my work so far: The conductivity of the PEC is \$...
1
vote
2answers
91 views

Reflection in low frequency conductors (not transmission line)

Is the reflection phenomenon common in RF work with unmatched source/load pairs also present at low frequencies? Or are the wavelengths so much longer than the physical conductor lengths that ...
1
vote
2answers
632 views

Pullup resistors. Does it make any difference what side of the series resistor?

The line is high frequency digital line. It has to be pulled up. Does the side of the series resistor make any difference? simulate this circuit – Schematic created using CircuitLab or ...
0
votes
1answer
55 views

Is this signal reflection or a damaged transmitter?

This is (an isolated, differential) capture, 1µs/div, of some Profibus communication over about 10m of cable. The first image is typical for about 90% of packets and seem fine. Most are +/-5v with ...
2
votes
0answers
92 views

How do you calculate phase shift induced by a shunt capacitor?

Given a simple loaded-line shunt-capacitor phase shifter, how can I calculate the phase shift and insertion loss at S21 caused by the shunt capacitor (varicap in my case, but for any cap) assuming I ...
0
votes
2answers
86 views

power waves and scattering matrix

I have some doubts about the concept of power waves used in the description of the scattering matrix of an N-port component. In particular, I was wondering what is the most general and correct ...
1
vote
1answer
66 views

Coax Cable Wave Impedance, Capacitive Load

I am studying the behaviour of cables over frequency, especially what a source sees, and have 2 Questions, as I did some simulations in LtSpice. As a model for the cable I used the "Lossy ...
1
vote
0answers
121 views

Impedance and resonance frequency of a bias tee

I am a beginner trying to learn about combining impedances and solving for the resonance frequency. I am solving a circuit: simulate this circuit – Schematic created using CircuitLab and I ...
0
votes
2answers
122 views

Signal reflections inside CPU?

Given the fact that the clock frequency is about one GHz and the corresponding wavelength is about the same order of magnitude (velocity of propagation is lower than 3 * 10^8 m/s inside the chip) with ...
1
vote
2answers
96 views

Meaning of S11 performing a clockwise arc circle about the smith chart origin?

I've tested a device with my VNA. It displays S11 in a Smith chart as a plot x(w) + iy(w) (w the frequency). Curiously, as w increases from 50KHz to 600MHz, the plot is an almost perfect 1/3 circle ...
0
votes
4answers
173 views

Why longer stubs cause more intense ringing?

Why connection of longer stub lengths cause more intense ringing in a Communication Network like CAN? As stub lengths increase won't the attenuation increase and lead to less ringing? Also the time ...
0
votes
4answers
208 views

Why is the amplitude of ringing in square wave independent of frequency of square wave?

Reflections in a transmission line is causing ringing in square wave because certain frequencies are getting enhanced, but when frequency of the square wave changes won't the amplitude of those ...
0
votes
1answer
90 views

Does the standard termination of 120 ohm really suppress reflections in recessive state in CAN?

Suppose we have a multi-node CAN network with the ends of transmission line terminated with the standard 120 ohm. When the recessive state is on the transmission line, the voltage on both CAN_H and ...
0
votes
1answer
53 views

How will the proper termination at one end while the other end is kept open avoids reflections in transmission line?

Consider a transmission line which is terminated with characteristic impedance at one end but other end is kept open, the reflections are not observed. I don't understand the mechanism behind. Please ...
3
votes
4answers
818 views

How do reflections of a square wave cause ringing in transmission lines?

When a square wave is applied to a transmission line which is not terminated with its characteristic impedance, reflection and ringing occur. I don't understand how sinusoidal ringing occurs when I ...
1
vote
2answers
84 views

Path of a signal traveling on a mismatched transmission line

I have a basic question about the path of a signal traveling on a transmission line with a short circuit as termination. Suppose that this line is driven by another line (at left) with Zc = 50 Ohm ...
1
vote
1answer
32 views

Falling and reflected impulse waveform - short circuit and void [closed]

What causes the signals to reflect differently when \$Z_L\$ = ∞ and when \$Z_L\$ = 0?
0
votes
1answer
43 views

Pads reflecting in controlled impedance strip?

Background I'm designing a controlled impedance line for a 1900MHz signal travelling between SIM7000A cellular chip and an antenna. Question Tuning circuits are recommended for antennas with series ...
0
votes
0answers
36 views

Time Domain Analysis with Vector Network Analyzer

I have done some measurements with a VNA in time domain (by using the transform operation of the instrument). Precisely, I have selected the measurement of S11 (reflection coefficient at port 1 of the ...
0
votes
0answers
48 views

Impedance matching to minimize VSWR

I was trying to determine what the impact of impedance mismatching would be to an RF output and I came across this. About half way down the page, the author makes this claim. In general, if the ...
1
vote
1answer
410 views

Input impedance of High - Frequency Amplifiers

I have a question about the choice of the input impedance of a high frequency amplifier. In general I know from elementary analog electronics courses that it is good for an amplifier (for instance an ...
2
votes
7answers
1k views

Reflect IR beam off reflector instead of emitting straight to TSOP receiver

I have a working set-up to detect beam breaks using an IR LED, modulated at 36kHz, and a TSOP receiver connected to a comparator. It outputs the count via Arduino. The range is about the width of a ...
1
vote
1answer
116 views

Refraction vs Reflection in Ultrasonic sensor for water level detection

I want to use ultrasonic module JSN-SR04 for detection of water level inside tank. The US module has single sensor for Transmission and Reception of US signals as shown below. I wonder if US sensor ...
6
votes
2answers
256 views

How do wireless receivers reject noise created by the original signal reflecting off walls?

When a transmitter emits an RF signal it reflects and bounces around all over. If a receiver is line-of-sight with that transmitter then the original signal will hit it first but signals bouncing off ...
1
vote
2answers
267 views

How does risetime affect transmissionline effects?

How do rise and fall times affect reflection in a transmission line? Reflection will occur with shorter lengths as rise times becomes shorter, does this mean risetime effects the wavelength of a ...
2
votes
1answer
160 views

Calculate the voltage across a load resistor for complex transmission lines

The following parameters are given: 500m homogeneous transmission line. ...
1
vote
0answers
552 views

Unitary property of scattering matrix

From s-parameter lossless network definition , The sum of the incident powers at all ports is equal to the sum of the reflected powers at all ports. But how do we derive the above unitary property ...
0
votes
1answer
38 views

relation between reflexion coefficient and power ratio

Assume you have an intermediate input/outpout device connected to a coaxial line. For example, the device may be a DC-bloc, a bias tee, or simply a PCB microstrip transmission line. Using a signal ...
0
votes
0answers
80 views

Impedance Matching and Reflection Coefficient

Consider a real signal generator (Voltage Source Vs, output impedance Zs, reflection coefficient Γs) and a load Zl with reflection coefficient Γl. I was told that we have maximum power transfer when ...
3
votes
1answer
90 views

Maximum VSWR that can be tolerated?

I am trying to solve the 2013 paper set by ISRO for electrical engineers. I wanted to verify if my answer to Question no 14 is correct. The maximum RMS current is 20A, so maximum tolerable RMS ...
0
votes
1answer
132 views

When is it important to handle reflections in pcb design?

I am watching some videos explaining how reflection can affect a signal and how you should treat these signals as transmission lines to remove reflection. I wanted to understand a more practical ...
0
votes
1answer
94 views

Why is the pulse reflection becoming like this in pulse?

I use mosfet to generate a pulse, input the pulse into the transmission line, and after the reflection, test the waveform as shown. Why did the third reflected waveform become like this? I calculated ...
0
votes
1answer
447 views

Average Power of load conected to an Ideal Transformer

Where does the 1/2 come from in the power equation?
2
votes
1answer
572 views

Have you ever fried a wi-fi router by leaving it to work without its external antennas?

I wonder if a wi-fi router can be damaged if its external antennas are unscrewed? Have you ever damaged such a router leaving it to work without antennas, like this: Source I know that there are ...
1
vote
0answers
108 views

Reflection on a matched transmission line [closed]

A matched load with source using a transmission line (assume real load and matched using quarter wave transformer) should not have any reflection ideally. But we can see that the load impedance is ...
1
vote
1answer
100 views

S-Parameters, Smith Chart, and Reflection Coefficients

Please help guide my ignorance on this topic. From what I understand, S-parameters are reflection coefficients generalized to N-port systems (via an S matrix), but for a 1-port system, these converge ...
1
vote
0answers
162 views

Some calculations on Transmission Lines

I have to do some (simple) calculations for a transmission line. I was given a power supply of \$11V\$/\$22\Omega\$, \$Z_0 = 50\Omega\$, \$v = 2.2 \times 10^8 m/s\$, a load capacitance of \$1.124nF\$ ...
2
votes
2answers
971 views

Impedance Matching: Minimum Reflection vs Maximum Power Transfer

The minimum reflection is achieved when the two "circuits" being connected have the same impedance. This makes sense because all the components of the wave can propagate without needing to be modified....
1
vote
1answer
71 views

Different types of reflection/TDR casic

I am trying to understand the theory of operation of a time domain reflectometer (TDR). TDR is a time domain instrument with measurement the impedance versus the distance. If with a VNA one can ...
0
votes
0answers
132 views

Dipole antenna director

Say a free metal rod is placed at a distance λ/2 from a dipole antenna (fig), both being of same length. I understand it will reflect and dampen the signal going to the left. But how will it impact ...
2
votes
1answer
61 views

IR emmiter and reciever layouts for custom sensor

I'm having a hard time designing a PCB for a sensor array that need to detect if there is a small reflective object (3-20 mm section) in the way. That object can slowly rotate around a shaft. I have ...