Questions tagged [propagation]

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Voltage propagation along a wire

Let's say you have a wire connected to a device that you can switch between high-voltage and ground voltage. The wire is not connected to anything on the other end. You're observing the voltage in two ...
74 views

How to read polar coordinates of radiation pattern

I have a PCB antenna which datasheet provides the following radiation pattern graphs: There seems to be a "weak" direction which the antenna signals is going to be very weak. Which direction is the "...
26 views

Guided propagation in transmission lines

Can you help me on understanding why we may say this transmission line the propagation is guided and there is not any radiation? It is a 2-conductors transmission line, in which the conductors are ...
41 views

Zeros in radiation of Smart Antennas

I have an exercise from a textbook about smart antennas. I think I have the right approach to solve this kind of problem. However, I'm not quite sure if I'm handling it correctly due to the additional ...
728 views

Do I need to maintain source of a signal till it reaches the destination?

If I send a signal through a wire having delay of 10ms, then should I need to maintain the source of the signal till it reaches the destination or can I change after, say, 2ms and send the next signal....
24 views

What is propagation delay in cmos nets?

I have read somewhere that signal travels as electromagnetic waves in wires near to speed of light. The signals are brought to destination by EM waves. Then what does electrons do? If signals travel ...
27 views

Propagation delay in full adder models

From my last question Propgation delay I tried to solve for the time delay that occurs at the last carry Not sure if I have done it right .. Please correct me if I m wrong
56 views

Propgation delay

I want to compare performance of 4-bit full adder vs sequantial (serial ) adder with one D flip flop .. The two models are in the followig figures Combinational adder: Serial adder: Lets say in ...
1k views

How is it possible to drive VGA displays at such high pixel clock frequencies?

I'm working on a digital circuit using discrete components to drive a 640x480 VGA display in a 80x30 text mode. For a 640x480 display, the pixel clock is 25.175MHz, which has a period around 40ns. I ...
42 views

What is the mode of a square waveguide $TE_{11}$ that is deformed into a circle?

I am trying to solve the 2013 paper set by ISRO for electrical engineers. I want some help to solve Question no 17 is correct. So I don't even know how to approach the problem, what will be the new ...
175 views

How to understand Transmission and Propogation delay formula

I have three questions below. I would like to understand how their respective answers were reached, this is a question in my current class and everyone in the class has A-Level mathematics experience -...
80 views

What kind of modulation technique and carrier frequency is used for interplanetary communication such as between the Earth and Mars? [closed]

I have just come across this wind sound coming from pressure sensor of Insight lander which is in Mars at the moment. I know basically that AM, FM, PSK, FSK ect. all have disadvantages and advantages ...
133 views

how to calculate the tpdhl / tpdlh for any given circuit

i am struggling on calculating the tpdhl / tplh i dont know how to calculate is there any algorethim for the way we calculate the time propagation high to low etc.. several questions asking to take ...
48 views

wave propagation ( pict) [closed]

Can someone explain to me what is a meaning of the starred items in this picture?
139 views

Calculate radiation power of an antenna in respect to a given antenna radiation pattern and a given angle

I work on a program that simulates the wave propagation of high frequency electromagnetic waves (2.4 or 5 GHz Bands) in 3D. I use a ray launching approach, where the emitted rays approximate the ...
43 views

True near field distance for a short monopole antenna

Antenna properties: Height x Diameter = 3.3 inches x 1.4 inches Test Frequency: 900 MHz (Wavelength = 33 cm or 13 inches) I see some conflicting formulas to calculate the near field distance for ...
46 views

Decide coherent time and fade duration through empirical studies on the channel and relate them to channel modeling

I. Scenario: TX floating in the lossy heterogeneous medium with undetermined positions within a limited region; RX fixed in the air and closed to the boundary of air-lossy medium; Frequency: 500 MHz ...
444 views

How does an RS-latch work in the presence of propagation delays?

I've long wondered how an RS-latch can work, given the existence of propagation delays. If the nor-gates have non-zero propagation delays (aka gate delays), wouldn't it need to be the case that: The ...
1k views

calculating propagation delay

We assume that every gate's delay is (microsecond). what is total propagation delay?
152 views

Measure S21 between 2 antennas at certain frequency using a Spectrum Analyzer

RX antenna is connected to the Spectrum Analyzer whose reading is regarded as P_RX. TX antenna is connected to a transceiver module that is set to work at the target frequency and emit certain power (...
63 views

How very high frequencies (VHF) are propagated during night over large distances?

I am new in telecomunications and this question just came up today and I coudn't find an explanation. Here is the most common model for the ionosphere: The ionosphere layer E is the main resposible ...
409 views

Ripple carry adder doubt

In a 4 bit ripple carry adder 4 full adders are connected serially, one FA waits for the carry input from the previous FA. My question is, when calculating the propagation delay, should we assume that ...
130 views

Impulse shorter than propagation delay

In an exercise I got an example circuit For one question, there is $S(t_0)=1$ for just $T/3$ (third of propagation delay [confusingly called transmission delay here] of every gate in circuit). ...
186 views

Does Longley–Rice model model takes into consideration Fresnel zone?

To an extent I understand Fresnel zone.But do know how Longley–Rice model takes Fresnel zone? In other words, how Fresnel zone concepts takes into account by the Longley–Rice model? Any comment would ...
65 views

Do number of reflections depend on frequency?

Consider there is a transmitter at A and receiver at B and transmitter is transmitting radio waves. Further there are obstacles of different sizes in between A and B. Now if we increase the frequency ...
71 views

Can we conclude from Friis formula that high frequency mean more loss.

I am trying to understand the Friis transmission formula: https://en.wikipedia.org/wiki/Friis_transmission_equation From the equation in terms of directivity can we conclude that higher the frequency ...
36 views

Can there a be a situation where two way propagation model is important in GHz range?

I assume that applicability different propagation model for wireless channel depends on the frequency of operation and the kind of obstacles or channel under consideration. My question is can anyone ...
2k views

Propagation delay in full adder

I'm dealing with a question about an implementation of a full adder with component delays. tpd(XOR) = 5 ns tpd(AND) = 2 ns tpd(OR) = 2 ns I'm having problems solving for the the propagation delay ...
47 views

How surface refractivity affect radio propagation?

This question is related to the following link and Longley-Rice Propagation Model https://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.453-11-201507-S!!PDF-E.pdf In the Longley-Rice Propagation Model ...
295 views

What does 80% or 60% of Fresnel zone mean?

This refers to the link https://en.wikipedia.org/wiki/Fresnel_zone In the link it is mentioned that: The rule of thumb is that the primary Fresnel zone would ideally be 80% clear of obstacles, but ...
65 views

What is white-space transmission loss?

This question refers to the link below: http://www.brighthubengineering.com/consumer-appliances-electronics/102752-the-longley-rice-propagation-model-and-tv-white-space-for-ultra-wifi/ What does this ...
126 views

Propagation delay and arrival time

I am trying to determine the arrival of signals from 3 separate beacons to point x. I have found the distances from x to each beacon as well the propagating wave speed but I do not know how to ...
67 views

Signal decimator/down-sample with lowest propagation delay

I would like to frequency-divide a 10 MHz digital signal by a factor of 8 or 16, with the lowest possible propagation delay. I need a propagation delay that is at most 5-10 ns. The best solution I ...
2k views

Are there types of standard coaxial cable with a propagation velocity of 0.9c? What would be the application?

Reading this answer I was surprised to hear that there are "excellent" kinds of coaxial cable with a propagation speed of 0.9c; 90% the speed of light. The bargain basement number is about 2/3c, and ...
3k views

Transition time (rise time) and propagation delay

Recently in class I have encountered the following calculation of the propagation delay of the following digital circuit: Could anyone please explain to me the addition of the rising time of X2 and C?...
123 views

How does modules in an asynchronous circuit know when to signal that their output is ready?

I have recently become fascinated by asynchronous CPUs, which have no central clock and each module instead sends a signal, when their data has been processed. However, I have been wondering how such ...
72 views

How to calculate latency of integrated product?

Is there a standard model for estimating the additional clocking latency which needs to be applied based on product interconnects? For example: Lets say a DDR memory has a switching time of 1 ns. ...
154 views

Complex RSSI dBm calculations with shield

I have a little bit of problem understanding complex attenuation calculations when there is a shield involved between the transmitter and the receiver. Let's take a simple example: We have a ...
652 views

Near field magnetic & electric wave impedance formulas

I am looking for the exact formulas for the impedance of an electric and magnetic wave in the near field region. We have some approximates: Zwe≈ 1 / (ω * ε0 *r) Zwm≈ (ω * µ0 *r) where r is the ...
641 views

Effect of changing the length of an inverter's N-mos transistor on the propagation delay

let's say we want to check the time it takes for our source Vdd to charge a capacitor through an inverter network. changing the width of the P-mos transistor will make more current flow, thus ...
2k views

Why does more bandwidth guarantee high bit rate?

The definition of bandwidth is frequency range and it seems to be correct to say that higher bandwidth guarantees higher data rate. However, i do not understand why it does. Data rate depends on ...
3k views

What causes the difference in tPLH and tPHL?

What causes the difference in propagation delays, for example on the SN7404N inverter, $t_{PLH} = 12-22$ ns, and $t_{PHL} = 8-15$ ns. Why is one longer than the other? Does it have to do with ...
820 views

Atmospheric attenuation calculation for a 1550nm link budget

My apologies in advance if this is the wrong place to ask this question. I was told that there were some RF communications experts here, so i figured there might be some FSO experience here as well. ...
629 views

Propagation delay in 4 inverter w/l ratio

hi guys, I was given a task on optimizing propagation delay of four inverters using cadence software. The circuit connection is shown in above figure. I was asked to change the ratio of w/l for pmos ...
72 views

How to find the polarization (phase) of the virtual source if image theory is used

Consider a radiating element (actual source) is placed above a ground plane, and if we apply image theory to determine the E-filed, the virtual source will be placed below the ground plane and ground ...
4k views

Propagation delay of a digital logic circuit

I'm trying to answer a question on propagation delay. The question is: Assuming the propagation delays for different circuits are as follow: 4 ns for XOR gate, 3 ns for OR gate, 5 ns for NAND gate ...
363 views

How much is the propagation velocity affected by the characteristic impedance?

Someone posted the (very educational!) video Similiarities of Wave Behavior from 1959 in another answer, and after watching the part about impedance mismatches, it strikes me that the propagation ...
195 views

How the relationship between input and output is derived in a comparator?

In the slide 6 of the page about propagation delay of a comparator, the time relationship between input and output is as below. However, I am not sure how the function between input and output voltage ...