Questions tagged [waveguide]

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1answer
29 views

Why is it not good to use a waveguide at low frequencies?

Which is the physical phenomenon behind this?
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1answer
12 views

How to explain the difference of attenuation of different pitch of sound by kinetic molecular energy?

How to explain the difference of attenuation of different pitch of sound by kinetic molecular energy ? I know that «sound of low frequencies travel farther in air than sound of high frequencies». ...
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1answer
34 views

Is there a difference between metal waveguides in microwave frequencies and dielectric waveguides in optical frequencies?

Do they work the same way? Do metal waveguides in MW also work through total internal reflection like in optical waveguides?
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20 views

How to analyse dielectric discontinuity in Waveguide?

I came across this question the solution given was to use the formulae for reflection coefficient with characteristic impedance of wave guide replacing the ones in boundless medium. What I am ...
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0answers
35 views

Shape of wavefronts for transverse modes in electromagnetic waveguide

I've been able to confuse myself about the shape (i.e. surface ripple/bend/tilt) of wavefronts for transverse modes in an electromagnetic waveguide, like a rectangular cross section waveguide with ...
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0answers
16 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 ...
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0answers
28 views

What is air band and band gap in Photonic crystal structure?

want to know the meaning of air band of photonic crytal
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0answers
15 views

what is bolch optical mode?

I have read some papers(https://arxiv.org/ftp/arxiv/papers/1206/1206.4342.pdf) where the word ''bolch mode'' used. Now I want to know what kind of optical mode this is and how or why it is generated?
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39 views

Number of TM Modes in Waveguide in MIM waveguide

I'm working on a practice question requiring me to find the total number of TM modes (including normal modes and SPP excitation modes) in a symmetric Metal-Insulator-Metal (MIM) waveguide only knowing ...
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0answers
13 views

Comparision of using two dimensional mode or one dimensional in case of optical data transmission

Many works have been done to increase capacity of optical communication. I saw that some researcher using 1-D mode ,some 2-D to implement their device.The reson of using 1-d/2-d beacuse of their types ...
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1answer
15 views

What is the relationship of optical mode and data?

This question is on the plot of mode division multiplexing system where it is said capacity crunch can be solved using mdm technique. Now, we know single mode fiber can transmit upto 1Tbps. Now if i ...
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0answers
41 views

Can I couple 1064 nm and its harmonic 532 nm in a single polarization maintaining fiber?

I have an experiment where I need to get a largish (40 mW) amount of 532 nm light and small amount (<50 µW) of 1064 nm light into a device under test. I need something with stable polarization so ...
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0answers
15 views

Why -20dB is taken as the standard rejection ratio for optical mode rejection in multimode waveguide?

In case of multimode waveguide to demonstrate perfect mode rejection, I saw researchers use boundary of -20dB. If mode power at output is less then -20dB, it is considered as fully rejected/filter out....
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36 views

What causes the upper limit on wavelength in optical fiber?

It's well known that a most given waveguide modes have a cutoff wavelength above which the mode is no longer supported. At low wavelengths, more modes are supported. But what happens at high ...
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0answers
30 views

How to measure wave vector from complex pressure?

I want to plot the dispersion relation in comsol for an acoustic waveguide. I am working in pressure acoustics, so my dependent variable is pressure. Comsol treats pressure as a complex number. How ...
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1answer
31 views

Waveguide wave equation

Consider a wave guide built from two parallel slabs at $x=0, x=L$. between the slabs there is a dielectric material with $\mu=\epsilon=1$ and electric conductivity with a frequency of $\sigma(\omega)=\...
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0answers
12 views

Transfer of momentum from a wave to it’s waveguide based on theta and the inertia of the wave?

Bit of a complicated one - I've been trying to understand how the energy in a wave dissipates or transfers it's energy to the walls of a wave guide as the angle of the wave guide changes. As the ...
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1answer
25 views

Frequency response of the waveguide

So, I have signal in the waveguide that is transmitted by two modes of radiation, for which the delay is for example $τ1 = 6ns$, $τ2 = 6.5ns$, respectively. And the energy supplied to the receiver by ...
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0answers
70 views

Leaky waveguide - calculating the frequency [closed]

The figure shows a waveguide with a square cross-section. The length of the side of the cross-section is $a = 3.5$ . A TE wave with a frequency f propagates in the waveguide in the positive direction ...
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1answer
40 views

Why does TEM mode not propagate in single conductor system?

In the Wikipedia article it is said: "In hollow waveguides (single conductor), TEM waves are not possible, since Maxwell's Equations will give that the electric field must then have zero divergence ...
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0answers
69 views

Using convolution to simulate acoustic dispersion in shallow water

Background I'm a marine biologist who's trying to wrap my head around shallow water propagation. I'm interested in how acoustic dispersion (as described by Pekeris' waveguide) alters how sounds ...
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0answers
24 views

what is the advantages of using 2-μm operating wavelength light in sdm/mdm technology? [closed]

Most of the work have been done in the communication band but recently there has been emerging interest in extending the operating wavelength of communication system to the short-wave infrared (2 μm). ...
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1answer
330 views

what is effective index method which is used to solve modes in rectangular waveguide? [closed]

I actually want to know the basics of effective index methods for solving the optical modes in slab/rectangular waveguides.
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1answer
48 views

Which wave is widely used in waveguides?

I've studied that the rectangular waveguides are widely used because they have less cut-off frequency and as we know that the cut-off frequency is one of the major factors for waveguides. The article ...
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2answers
31 views

Does the electromagnetic wave inside a waveguide experience matter wave behavior?

The electromagnetic wave inside a wave-guide has a longitudinal component besides the transverse one. Does this imply it has an effective mass? It is shown to do so by Wang in https://arxiv.org/ftp/...
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1answer
76 views

Noise covariance matrix

I've been trying to understand this paper. The paper seems to be about analyzing noise properties of a superconducting coplanar waveguide microwave resonator. They use an IQ mixer to perform ...
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2answers
233 views

What is a leaky mode of a waveguide?

I know that in a waveguide is possible to distinguish between guided modes and radiative modes. For example, in a planar waveguide, a guided mode is oscillatory inside the core and vanishes ...
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1answer
74 views

Dielectric Slab Waveguide

I have a question about dielectric slab waveguides. In these type of waveguides, n1>n2. What would happen in the case of n2>n1? I think there would be no propogation through the waveguide, but I am ...
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0answers
80 views

Input impedance of a line with complex load

I am currently studying electromagnetism mostly with the help of the book "Microwave Engineering" and when trying to solve problems which main goal is to compute the input impedance of a lossless ...
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0answers
75 views

Physical origin of transverse waveguide modes

I've been working with multimode lasers for a couple of months now, and whilst I have a good understanding of what their output looks like and what longitudinal modes are, I continue to be absolutely ...
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1answer
668 views

Why are TM_10 modes not possible in a non-magnetic waveguide?

In a hollow rectangular waveguide, we may either propagate transverse electric modes (TE$_{mn}$) where we have electric standing waves quantified by m and n in each direction, or transverse magnetic ...
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1answer
121 views

Why are electromagnetic fields in free space (isotropic and homogeneous) constant over all time and space?

I see very often that electric and magnetic fields ($\mathbb{R}^3$) in free space are assumed to have the form: $$\vec{E}=\vec{E}_0{(x,y)}\exp{[i(wt-kz)]}$$ $$\vec{H}=\vec{H}_0{(x,y)}\exp{[i(wt-kz)]}$...
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1answer
239 views

Evanescent waves and “phase-matching” argument

I have looked through several Classical ED approaches to introduce evanescent waves, but still can't build the connections. I was told that evanescent waves are needed to satisfy boundary conditions ...
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1answer
62 views

Infinitely circling ray! (solving the eikonal equation in polar coordinates) - can I think of this in terms of waveguides? [closed]

In short: I want to know the necessary conditions in order for a ray to 'bend backwards' and complete a full circle. In detail: Suppose theres a medium with a radially symmetric index of ...
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1answer
101 views

Finding the resonant frequency of a rectangular resonator filled with a magnetic material

The prompt is to find the resonant frequency $f_r$ of a rectangular resonator which is filled with a magnetic material rather than standard air or vacuum. I'm confused as how the resonance frequency ...
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2answers
60 views

Confusion between a signal sent at a given frequency and the Fourier components?

I have been reading about phase and group velocity (maybe the context will be useful here) and was attempting a question when I became rather stumped. The question was Square pulses are sent along ...
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0answers
27 views

Why does the fundamental mode have the smallest loss in waveguide structures?

Why does the fundamental mode have the smallest loss in waveguide structures?And why the higher the order of the mode,the smaller the value of the angle between the light and the normal vector on the ...
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1answer
787 views

Why the relationship $v_p v_g = c^2$ (phase velocity multiply group velocity equals lightspeed squared) exists in waveguide structures?

What’s the reason that the relationship of de Broglie hypothesis(hypothesis-->relations) will hold in Waveguide structures?
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1answer
426 views

Why TE0 mode does not exist in parallel plates?

In parallel plates, TM0 mode will become TEM0 mode, but why TE0 mode does not exist? How to explain it with its physical properties?
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3answers
139 views

Propagating modes in a waveguide, what do they represent?

In a hollow rectangular wave guide of dimensions $a \times b$ for example, I know how to apply the boundary conditions to find the solutions. In particular, for TE (or TM) modes we have the expression ...
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1answer
106 views

Why can't $m$ or $n$ be zero on $TMmn$ mode in a rectangular waveguide?

The question is that is there any analytical or practical issue if m or n become zero in TMmn mode for a rectangular waveguide? It could probably be a simple question but I'm not sure about why does ...
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2answers
451 views

Standing wave ratio inside a waveguide

If there were microwaves being transmitted through the waveguide in the image below out the horn, and I place a sheet of metal in front of the horn (perpendicular to the propagation of the waves), ...
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1answer
57 views

Input impedances of terminated sections of transmission line

When dealing with optics and dielectric waveguides, a way to obtain the guided modes is to impose the "transverse resonance condition". Let the following be a transmission line with characteristic ...
2
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1answer
795 views

The boundary conditions in a waveguide

Suppose a cubic waveguide, made of perfect conductor, has only two open parallel sides. And the boundary conditions in this case are that the electric field at the surface must satisfy: $$\vec{B} \...
2
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1answer
96 views

Boundary condition on $\mathbf{B}$ to describe resonant cavities from waveguides

In Jackson- Classical Electrodynamics when resonant cavities are discussed (8.6, page 252) (but also at page 7 here or at page 19 here) the explanation is made by saying that the solution is the same ...
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1answer
1k views

Imaginary components of Poynting vector in rectangular waveguide

Consider a rectangular wave guide, as in the example of Jackson - Classical Electrodynamics The Poynting vector turns out to be $$\vec{S}=\epsilon c^2 \vec{E_0} \times \vec{B_0} e^{2i(kct-\alpha z)}...
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1answer
78 views

Need help understanding another answer on TEM coaxial cable modes

Background: If I make a coaxial waveguide from the gap between two long, perfectly conducting, coaxial cylindrical surfaces, (e.g. perfect "coax" cable), then if I apply charges of $+q$ and $-q$ to ...
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0answers
64 views

Propagation of multiple photons in a waveguide lattice

Hamiltonian describing photonic lattice made of N elements can be written as: $$H = \hbar\sum_{i=1}^{N} (\beta_{i} \hat{a}_{i}^{\dagger}\hat{a}_{i}+\sum_{j=1}^{N}\kappa _{ij} \hat{a}_{j}^{\dagger}\...
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0answers
106 views

Waveguide eigenmode weak-form (Comsol)

Maxwell equations are: $$\nabla \times \mathbf{E} = -\frac{\partial \mathbf{B}}{\partial t},\,\,\,\,\,\,\,\,\nabla \times \mathbf{H} = +\frac{\partial \mathbf{D}}{\partial t}$$ Subject to the ...
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1answer
828 views

Meaning of imaginary part of complex field amplitude for waveguide modes (e.g. TE, TM, HE, EH)

In classical waveguide analysis (e.g. for optical fibers, as in the notes Modal analysis of step-index fibers, ECE 4006/5166 Guided Wave Optics, Robert R. McLeod, University of Colorado), one can find ...