wave propagation in wave guide

[chaitu_b99]

Hi,
Can anyone please tell me, how many waves can be propagated in a wave guide.

 

[pstuckey]

I think you're referring to modes?

Waveguides are specified so that there is only one dominant mode of propagation. For instance, WR-15 is specified for 50-75 GHz. When used over that frequency range only one mode (TE.01) will propagate.

 

[redcrtystalline]

hi
if im understanding right you means modes,there is infinite number of modes that can propagate in waveguide
regards

 

[chaitu_b99]

Hi,
I know tat infinite number if modes can be traveled in a wave guide . Wat abt the number of waves, is it tat only one wave can travel in a wave guide with different modes ???

 

[redcrtystalline]

as i said yah, but the condition for existence of multi wave in waveguide is that you should excite all of them in same time ,
as different modes have different maximum field location in general then there is is a limitation
regards

 

[chaitu_b99]

Hi,
Is it necessary tat to excite all the waves at the same time, the waves can be out of phase rite. Is there will be any interference in the waves if they are excited at different times.Please explain.

 

[redcrtystalline]

hi
1- no that is no need to excite all of them except for circular polarization or multimode use
2-i have doubt that we can use term of out of phase for this situation because this waves are excited and received separatlly(except for circular polarization)
3-i have not seen any application that excite modes in different time, but in different time there is not interference but in same time there is,
4-usually we are interested in first mode, because when we excite all modes in same time ,there is \ difficulties of several mode excitation (feeding) and inter modes interference

 

[redcrystalline]

hi , you can see advanced electromagnetic theory by balanis
this is best general reference for microwave waveguide
regards

 

[redcrystalline]

hi im sure that every mode can have phase difference with another mode and thats because s parameter is a complex number and it has its own phase

 

[chaitu_b99]

Hi,
Yes it is correct, but he waves should be with the different phase in order to avoid interference....

 

[redcrystalline]

hi
i cant understand how phase difference avoid interference?!

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hi
i cant understand how phase difference avoid interference?!