# Tagged Questions

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### Do Conch shell horns produce infrasound?

I was just reading an article about some guys at Stanford playing with ancient conch shell horns: http://news.stanford.edu/news/2011/february/conch-acoustic-musicians-020711.html They mention feeling ...
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### Ultrasound in hollow tube

Ultrasound in pulse-echo mode (reflection from air-water interface) is used to measure the level in a tank filled with water. Since the level is several meters, a hollow steel tube is used to ...
332 views

### Fiber optics with broadband, incoherent light

I wonder if someone could help clarify waveguiding with broadband, incoherent light please. If we take a telecomms fiber, which is single-moded above ~1.4 μm and couple a laser beam in, we assume ...
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### trouble calculating dispersion curve for TE Mode symmetrical step-index waveguides

I'm trying to work on a problem where I'm needing to show the dispersion curves for a slab waveguide. I'm given the refactive index of the core, $n_1$, the refractive index of the cladding, $n_2$, the ...
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### Reflection coefficient of transition coaxial and wave guide

Suppose you have a 1 GHz generator connected to a wave guide with a coaxial cable with a characteristic impedance of $Z_c =45 \Omega$. The wave guide is connected to the system which has a reflection ...
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### What is the meaning of the Fourier Transform of the electric field of a well guided mode in a dielectric waveguide?

I have been studying waveguiding in dielectrics for a while now; however, I cannot understand the meaning of the Fourier transformed electric field. I will first give some background information. ...
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### how do hybrid plasmonic waveguides work?

I was hoping that someone could clarify the operation of hybrid plasmonic waveguides for me. what I read on wikipedia left me with some questions: If the operation is based on coupling the ...
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### Why are photonics fibers called band gap fiber?

Why are photonics fibers called band gap fibers? Do the photonic fibers guide light inside the band gap or outside? What creates the band structure?
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### Reconciling total internal reflection and the evanescent Wave

I understand that light is guided in a dielectric waveguide via total internal reflection. My question is regarding the origin of power contained in the evanescent field traveling along the direction ...
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### Sequence of Transmission Lines [closed]

This is in relation to a practice question I was doing. I believe I'm aware of the theory surrounding the question - I'm just not sure how I can actually get the answer that the question is looking ...
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### In a waveguide, where does the energy in attenuated waves go?

In an electromagnetic waveguide, there is generally a "cutoff frequency." Electromagnetic waves with a frequency that is lower than this cutoff frequency will not propagate at all -- i.e., they will ...
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### Why you need at least two conductors for Transverse electromagnetic (TEM) propagation in a waveguide?

Do the two conductors have to be separated (no current flowing) or 2 connected lines? Of course both connected to a generator? Thinking about the Maxwell equations I guess the 2 conductors are ...
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### Increase Phase Velocity by Losing Power

I just read some words from the book Optical Waveguide Theory by Snyder, Allan W., p226. It says that However, although it is possible for the phase velocity of a mode to exceed the maximum speed ...
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### Why are waveguide fields not infinite?

I was reading The Feynman Lectures on Physics, Volume II, when I got to the section on waveguides. Toward the end, Feynman uses the concept of an infinite number of alternating line sources to explain ...
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### Distance between minima's of standing wave in a wave guide

I just started studying waveguides, i have a basic doubt about the standing wave pattern in waveguide. How are the m,n values related to the distance between the minima's? I read in a book that , ...
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### Which waveguide mode will be excited by circularly polarized laser mode $\mathrm{TEM}_{00}$ entering hollow fiber?

Linearly polarized Gaussian mode $\mathrm{TEM}_{00}$ mode, would couple into HE modes of circular hollow fiber. Which modes would circular polarized beam excite entering hollow circular fiber ?
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### Can one make a propagating field along a waveguide only have longitudinal/transverse components?

We know that in free space, a propagating electromagnetic wave is always transverse. However, along a dielectric waveguide, the propagating wave can have longitudinal components. The exist of the ...
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### phase velocity in dielectric lined waveguide

I want to simply calculate the phase velocity of a mode in a dielectric loaded waveguide but am having difficulty arriving at a sensible answer. Here I consider only a TM mode. The problem is ...
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### Transverse electromagnetic (TEM) mode waveguide

Suppose we have a parallel plate waveguide operating solely in the TEM mode, composed of perfect conductors. I understand that the electric field must terminate perpendicularly on the plates, where a ...
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### Wave propagation in micro strip waveguide

I am trying to understand wave propagation in micro-strip waveguide, the way i came to understand rectangular waveguide is this way (in brief): EM waves can be understood as reflecting from the ...
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### Transmission of light, sub-wavelength apertures, and cut-off frequencies

I was hoping someone could please explain how the transmission of light through a sub-wavelength aperture in a metal film, at a particular wavelength, changes when the aperture is: i) above cut-off ...
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### Can someone please explain extraordinary optical transmission (EOT)?

Can someone please explain extraordinary optical transmission (EOT)? I'm hoping someone can describe the physical process by which light is transmitted through a periodic metal hole array which is ...
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### calculate the length and width a of waveguide for a span of frequency

I know how to calculate the length and width of a rectangular waveguide when the cut off frequency is given. But when a span of frequency is given how do we calculate it? Here what is given by a span ...
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### Dispersion relation in wave guides

I am reading Griffiths section 9.5. Assume that wave guides are surrounded by perfect conductors, and geometry is $z$-independent, as in the text. I understand he proved that in a hollow wave guide, ...
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### How can electric and magnetic fields have any component in the direction of propagation of electromagnetic waves?

In case of waveguides we talk about $E$ and $H$ having non zero component in the direction of propagation of wave. But the entire basis of EMW is that $E$ and $H$ are perpendicular to the direction of ...
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### Coaxial waveguide - wave impedance

Determine the capacity $C$ per $m$, the inductance $L$ per m and the wave impedance $Z_0$ for a coaxial waveguide with inner radius $a$ and outer radius $b$. How large would $b$ have to be so ...
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### Cantenna and waveguide

I'm studying for a lecture of RF and wave guides and i'm currently building a cantenna. I have two questions about it construction and on how it works. My questions are about the lengths of the ...
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### EmDrive Cavity modes

The EMDrive described in patent application GB 2493361 is a simple section of a sphere surrounded by a superconducting cooling system. I have attempted to solve the oscillation modes possible and ...
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### Is the EmDrive, or “Relativity Drive” possible?

In 2006, New Scientist magazine published an article titled Relativity drive: The end of wings and wheels1 [1] about the EmDrive [Wikipedia] which stirred up a fair degree of controversy and some ...
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### Optical Waveguide's “Base Bandwidth”

Consider a dielectric slab waveguide (lossless, isotropic) illuminated transversally from the vacuum (with coherent, monochromatic light). We define the base bandwidth of a waveguide (or optical ...
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### Waveguides and Maxwell's Equations

Background In many textbooks on electromagnetism, the sequence in which topics are introduced are generally as follows -- electrostatics, magnetostatics, electrodynamics, wave propagation in free ...
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### Electric Field in Circular waveguide in TE mode

I know that the magnetic field inside a circular waveguide is $B_z=B_0\dfrac{\rho}{R}\left(1-\dfrac{\rho}{2R}\right)\cos{\phi}\sin{\frac{\pi z}{d}}$ How can I find the two components of the electric ...
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### Longitudinal EMAG wave?

I'm reading about optical waveguide analysis, and often come across the terms "transverse electric mode" vs. "transverse magnetic mode". As I unerstand, it means that the electric/magnetic field has ...
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### Waveguides (in the ocean?)

The speed of sound in the ocean is given by $$c_s(\theta,z) = 1450 + 4.6\theta - 0.055\theta^2 + 0.016z$$ $\theta$ is the temperature in degrees celcius, and $z$ is the depth. In a simplified model, ...
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### Non reflecting boundaries in waveguides

Can someone please explain the Sommerfeld radiation condition and what is the alternative non-reflecting boundary conditions for waveguides of general geometries?
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### Optical waveguide that can displace a 4D light field

Has anyone invented an optical waveguide that can "pipe" a scene from one place to another unaltered? More precisely, I want to displace (and/or rotate) a 4D light field. An optical waveguide is an ...
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### Is the acceleration and deceleration of a wave instantanious?

When an light travels in free space, it has a velocity of propagation equal to the speed of light. However, then the light enters a medium with a refractive index of n, the velocity of propagation ...