Modes in Waveguide

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Modes in Waveguide

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Jack// ani
Guest

Posted: Fri Dec 09, 2005 5:35 pm Post subject: Modes in Waveguide

Hi all, What is physical significance of various different modes travelling inside the waveguide? Why are they so critical, when talking about confined medium, like waveguide and optic fibre. As it hardly have any significance in free space!! Thanks

Bruce Scott TOK
Guest

Posted: Fri Dec 09, 2005 5:35 pm Post subject: Re: Modes in Waveguide

Quote:

Hi all,

What is physical significance of various different modes travelling
inside the waveguide? Why are they so critical, when talking about
confined medium, like waveguide and optic fibre. As it hardly have any
significance in free space!!

Boundary conditions for the Maxwell equations...

--
ciao,
Bruce

drift wave turbulence: http://www.rzg.mpg.de/~bds/

Tim Wescott
Guest

Posted: Sat Dec 10, 2005 12:17 am Post subject: Re: Modes in Waveguide

Jack// ani wrote:

Quote:

the energy has to make to travel a given distance (yes, my E&M theory
_is_ rusty). Different modes travel at different speeds, so if you have
multiple modes they'll disperse the signal, which slows your achievable
data rate (or bandwidth).

No bounces in free space means there's only one 'mode'.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

PD
Guest

Posted: Sat Dec 10, 2005 12:38 am Post subject: Re: Modes in Waveguide

Jack// ani wrote:

Quote:

Which goes to show you that a *solution* to the equations that reflect
a physical law do not have to have common properties with each other or
even with the law itself. (A law may have a symmetry that the solution
does not.) Boundary conditions form additional constraints to the
solution.

PD

Phil Hobbs
Guest

Posted: Sat Dec 10, 2005 12:53 am Post subject: Re: Modes in Waveguide

Tim Wescott wrote:

Quote:

Jack// ani wrote:

Hi all,

What is physical significance of various different modes travelling
inside the waveguide? Why are they so critical, when talking about
confined medium, like waveguide and optic fibre. As it hardly have any
significance in free space!!

Thanks

Different modes in a waveguide roughly equate to the number of bounces
the energy has to make to travel a given distance (yes, my E&M theory
_is_ rusty). Different modes travel at different speeds, so if you have
multiple modes they'll disperse the signal, which slows your achievable
data rate (or bandwidth).

No bounces in free space means there's only one 'mode'.

Rusty is the word. There is a continuum of modes in free space, because
a mode is just a propagating solution of Maxwell's equations in the
given geometry. A metal guide has a whole number of modes (a positive
integer or zero), and dielectric guides have at least one guided mode
and a continuum of unguided modes. (There's no analogue of a
waveguide-below-cutoff filter in the dielectric guide world.)

Cheers,

Phil Hobbs

Tim Wescott
Guest

Posted: Sat Dec 10, 2005 1:28 am Post subject: Re: Modes in Waveguide

Phil Hobbs wrote:

Quote:

Tim Wescott wrote:

Jack// ani wrote:

Hi all,

What is physical significance of various different modes travelling
inside the waveguide? Why are they so critical, when talking about
confined medium, like waveguide and optic fibre. As it hardly have any
significance in free space!!

Thanks

Different modes in a waveguide roughly equate to the number of bounces
the energy has to make to travel a given distance (yes, my E&M theory
_is_ rusty). Different modes travel at different speeds, so if you
have multiple modes they'll disperse the signal, which slows your
achievable data rate (or bandwidth).

No bounces in free space means there's only one 'mode'.

Rusty is the word. There is a continuum of modes in free space, because
a mode is just a propagating solution of Maxwell's equations in the
given geometry. A metal guide has a whole number of modes (a positive
integer or zero), and dielectric guides have at least one guided mode
and a continuum of unguided modes. (There's no analogue of a
waveguide-below-cutoff filter in the dielectric guide world.)

Cheers,

Phil Hobbs

Oh, right. Hermetians and all that. But the free-space modes all go
the same speed so it's not the Big Deal that it is with waveguides,
unless you're trying for a perfectly circular spot out of a laser.

Now I'm less rusty.

Thanks.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Dastardly Fiend
Guest

Posted: Sat Dec 10, 2005 1:36 am Post subject: Re: Modes in Waveguide

"Jack// ani" <nospam4u_jack@yahoo.com> wrote in message
news:1134148104.083337.327010@o13g2000cwo.googlegroups.com...

Quote:

One word: Resonance.
Waveguides, optical fibres, coaxial cables, antennae, tuning forks, pipe
organs, flutes and oboes and even violins. Resonance.

http://hyperphysics.phy-astr.gsu.edu/hbase/waves/standw.html#c4
http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/waves/swf.gif
http://id.mind.net/~zona/mstm/physics/waves/standingWaves/standingWaves1/StandingWaves1.htmlAndrocles.

Dastardly Fiend
Guest

Posted: Sat Dec 10, 2005 1:36 am Post subject: Re: Modes in Waveguide

"PD" <TheDraperFamily@gmail.com> wrote in message
news:1134153486.059991.303040@g47g2000cwa.googlegroups.com...

Quote:

Jack// ani wrote:
Hi all,

What is physical significance of various different modes travelling
inside the waveguide? Why are they so critical, when talking about
confined medium, like waveguide and optic fibre. As it hardly have any
significance in free space!!

Thanks

Which goes to show you that a *solution* to the equations that reflect
a physical law do not have to have common properties with each other or
even with the law itself. (A law may have a symmetry that the solution
does not.) Boundary conditions form additional constraints to the
solution.

PD
The symmetry is there, you just have to find it.

http://id.mind.net/~zona/mstm/physics/waves/standingWaves/standingWaves

Androcles.

Rich Grise
Guest

Posted: Sat Dec 10, 2005 5:35 pm Post subject: Re: Modes in Waveguide

On Fri, 09 Dec 2005 22:43:46 +0000, Dastardly Fiend wrote:

Quote:

"Jack// ani" <nospam4u_jack@yahoo.com> wrote in message
news:1134148104.083337.327010@o13g2000cwo.googlegroups.com...
Hi all,

What is physical significance of various different modes travelling
inside the waveguide? Why are they so critical, when talking about
confined medium, like waveguide and optic fibre. As it hardly have any
significance in free space!!

Thanks

One word: Resonance.
Waveguides, optical fibres, coaxial cables, antennae, tuning forks, pipe
organs, flutes and oboes and even violins. Resonance.

http://hyperphysics.phy-astr.gsu.edu/hbase/waves/standw.html#c4
http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/waves/swf.gif
http://id.mind.net/~zona/mstm/physics/waves/standingWaves/standingWaves1/StandingWaves1.htmlAndrocles.

You've omitted "sinus cavities" and "exhaust headers". ;-)

Ever see that "Blue Man Group" bit where they've got a telescoping piece
of about 6" PVC pipe, and one guy beats on it with drumsticks while another
slides the telescoping part of the pipe in and out? Resonance. :-)

Planetary orbits, electronic orbitals, NMR/MRI, etc, etc, etc...

Cheers!
Rich

Robert Baer
Guest

Posted: Sun Dec 11, 2005 9:35 am Post subject: Re: Modes in Waveguide

Rich Grise wrote:

Quote:

On Fri, 09 Dec 2005 22:43:46 +0000, Dastardly Fiend wrote:

"Jack// ani" <nospam4u_jack@yahoo.com> wrote in message
news:1134148104.083337.327010@o13g2000cwo.googlegroups.com...

Hi all,

What is physical significance of various different modes travelling
inside the waveguide? Why are they so critical, when talking about
confined medium, like waveguide and optic fibre. As it hardly have any
significance in free space!!

Thanks

One word: Resonance.
Waveguides, optical fibres, coaxial cables, antennae, tuning forks, pipe
organs, flutes and oboes and even violins. Resonance.

http://hyperphysics.phy-astr.gsu.edu/hbase/waves/standw.html#c4
http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/waves/swf.gif
http://id.mind.net/~zona/mstm/physics/waves/standingWaves/standingWaves1/StandingWaves1.htmlAndrocles.

You've omitted "sinus cavities" and "exhaust headers". ;-)

Ever see that "Blue Man Group" bit where they've got a telescoping piece
of about 6" PVC pipe, and one guy beats on it with drumsticks while another
slides the telescoping part of the pipe in and out? Resonance. :-)

Planetary orbits, electronic orbitals, NMR/MRI, etc, etc, etc...

Cheers!
Rich

One of the more interesting modes (in a waveguide) is the "smoke

ring" mode...apparently not very stable but capable of handling vast
amounts of power.
Now just figgure how to launch energy in such a mode, and....ray gun!

Dastardly Fiend
Guest

Posted: Sun Dec 11, 2005 9:35 am Post subject: Re: Modes in Waveguide

"Rich Grise" <richgrise@example.net> wrote in message
news:pan.2005.12.10.17.07.27.167686@example.net...

Quote:

On Fri, 09 Dec 2005 22:43:46 +0000, Dastardly Fiend wrote:

"Jack// ani" <nospam4u_jack@yahoo.com> wrote in message
news:1134148104.083337.327010@o13g2000cwo.googlegroups.com...
Hi all,

What is physical significance of various different modes travelling
inside the waveguide? Why are they so critical, when talking about
confined medium, like waveguide and optic fibre. As it hardly have any
significance in free space!!

Thanks

One word: Resonance.
Waveguides, optical fibres, coaxial cables, antennae, tuning forks, pipe
organs, flutes and oboes and even violins. Resonance.

http://hyperphysics.phy-astr.gsu.edu/hbase/waves/standw.html#c4
http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/waves/swf.gif

http://id.mind.net/~zona/mstm/physics/waves/standingWaves/standingWaves1/StandingWaves1.htmlAndrocles.

You've omitted "sinus cavities" and "exhaust headers". ;-)

Ever see that "Blue Man Group" bit where they've got a telescoping piece
of about 6" PVC pipe, and one guy beats on it with drumsticks while
another
slides the telescoping part of the pipe in and out?

No.
I do know what a trombone is.
Androcles.

Resonance. :-)

Quote:

Planetary orbits, electronic orbitals, NMR/MRI, etc, etc, etc...

Cheers!
Rich

Mark Fergerson
Guest

Posted: Sun Dec 11, 2005 5:35 pm Post subject: Re: Modes in Waveguide

Robert Baer wrote:

Quote:

Rich Grise wrote:

On Fri, 09 Dec 2005 22:43:46 +0000, Dastardly Fiend wrote:

"Jack// ani" <nospam4u_jack@yahoo.com> wrote in message
news:1134148104.083337.327010@o13g2000cwo.googlegroups.com...

Hi all,

What is physical significance of various different modes travelling
inside the waveguide? Why are they so critical, when talking about
confined medium, like waveguide and optic fibre. As it hardly have any
significance in free space!!

One word: Resonance.
Waveguides, optical fibres, coaxial cables, antennae, tuning forks, pipe
organs, flutes and oboes and even violins. Resonance.

http://hyperphysics.phy-astr.gsu.edu/hbase/waves/standw.html#c4
http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/waves/swf.gif
http://id.mind.net/~zona/mstm/physics/waves/standingWaves/standingWaves1/StandingWaves1.htmlAndrocles.

You've omitted "sinus cavities" and "exhaust headers". ;-)

Ever see that "Blue Man Group" bit where they've got a telescoping piece
of about 6" PVC pipe, and one guy beats on it with drumsticks while
another
slides the telescoping part of the pipe in and out? Resonance. :-)

Planetary orbits, electronic orbitals, NMR/MRI, etc, etc, etc...

Cheers!
Rich

One of the more interesting modes (in a waveguide) is the "smoke ring"
mode...apparently not very stable but capable of handling vast amounts
of power.

The what mode? Cites?

Quote:

Now just figgure how to launch energy in such a mode, and....ray gun!

Betcha it can't propagate in free space.

Mark L. Fergerson

hobart Zklfed
Guest

Posted: Mon Dec 12, 2005 9:35 am Post subject: Re: Modes in Waveguide

"Mark Fergerson" <nunya@biz.ness> wrote in message
news:HTXmf.17126$Mi5.5325@dukeread07...

Quote:

Robert Baer wrote:
Rich Grise wrote:

On Fri, 09 Dec 2005 22:43:46 +0000, Dastardly Fiend wrote:

"Jack// ani" <nospam4u_jack@yahoo.com> wrote in message
news:1134148104.083337.327010@o13g2000cwo.googlegroups.com...

Hi all,

What is physical significance of various different modes travelling
inside the waveguide? Why are they so critical, when talking about
confined medium, like waveguide and optic fibre. As it hardly have any
significance in free space!!

One word: Resonance.
Waveguides, optical fibres, coaxial cables, antennae, tuning forks,
pipe
organs, flutes and oboes and even violins. Resonance.

http://hyperphysics.phy-astr.gsu.edu/hbase/waves/standw.html#c4
http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/waves/swf.gif
http://id.mind.net/~zona/mstm/physics/waves/standingWaves/standingWaves1/StandingWaves1.htmlAndrocles.

You've omitted "sinus cavities" and "exhaust headers". ;-)

Ever see that "Blue Man Group" bit where they've got a telescoping piece
of about 6" PVC pipe, and one guy beats on it with drumsticks while
another
slides the telescoping part of the pipe in and out? Resonance. :-)

Planetary orbits, electronic orbitals, NMR/MRI, etc, etc, etc...

Cheers!
Rich

One of the more interesting modes (in a waveguide) is the "smoke ring"
mode...apparently not very stable but capable of handling vast amounts of
power.

The what mode? Cites?

Now just figgure how to launch energy in such a mode, and....ray gun!

Betcha it can't propagate in free space.

EZ, no problem, done all the time. But it aint called "smoke ring"
U can use your microwave oven, put a "structure" on it and cook a hotdog at
100 feet.

Robert Baer
Guest

Posted: Mon Dec 12, 2005 9:35 am Post subject: Re: Modes in Waveguide

hobart Zklfed wrote:

Quote:

"Mark Fergerson" <nunya@biz.ness> wrote in message
news:HTXmf.17126$Mi5.5325@dukeread07...

Robert Baer wrote:

Rich Grise wrote:

On Fri, 09 Dec 2005 22:43:46 +0000, Dastardly Fiend wrote:

"Jack// ani" <nospam4u_jack@yahoo.com> wrote in message
news:1134148104.083337.327010@o13g2000cwo.googlegroups.com...

Hi all,

What is physical significance of various different modes travelling
inside the waveguide? Why are they so critical, when talking about
confined medium, like waveguide and optic fibre. As it hardly have any
significance in free space!!

One word: Resonance.
Waveguides, optical fibres, coaxial cables, antennae, tuning forks,
pipe
organs, flutes and oboes and even violins. Resonance.

http://hyperphysics.phy-astr.gsu.edu/hbase/waves/standw.html#c4
http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/waves/swf.gif
http://id.mind.net/~zona/mstm/physics/waves/standingWaves/standingWaves1/StandingWaves1.htmlAndrocles.

You've omitted "sinus cavities" and "exhaust headers". ;-)

Ever see that "Blue Man Group" bit where they've got a telescoping piece
of about 6" PVC pipe, and one guy beats on it with drumsticks while
another
slides the telescoping part of the pipe in and out? Resonance. :-)

Planetary orbits, electronic orbitals, NMR/MRI, etc, etc, etc...

Cheers!
Rich

One of the more interesting modes (in a waveguide) is the "smoke ring"
mode...apparently not very stable but capable of handling vast amounts of
power.

The what mode? Cites?

Now just figgure how to launch energy in such a mode, and....ray gun!

Betcha it can't propagate in free space.

EZ, no problem, done all the time. But it aint called "smoke ring"
U can use your microwave oven, put a "structure" on it and cook a hotdog at
100 feet.

Err...at Stanford Linear Accelerator Center, they wer using higher

power klystrons, and to handle the power without arcing, was to use the
"smoke ring" mode.
That is what they called it because of the shape of the E-H mode.
Argue with them.

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