[SI-LIST] Re: TEM wave propagation and standing waves
- From: Ankit wangoo <ankit.wangoo@xxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Mon, 4 Mar 2013 22:39:36 +0530
Thanks for response, now i have better understanding of this topic.thanks
On Mon, Mar 4, 2013 at 11:11 AM, Ihsan Erdin <erdinih@xxxxxxxxx> wrote:
> You're right. In normal (unperturbed) propagation mode they will be in
> phase but spatially perpendicular to each other. However, standing waves
> are the result of boundary conditions (terminal conditions in the case of
> transmission lines.) The different behavior of electric and magnetic fields
> when they interact with matter (that is, the tangential component of
> E-field and normal component of H-field being continuous across a boundary)
> is the cause of phase difference on the standing waves.
>
> Regards.
>
> Ihsan Erdin
>
>
> On Sun, Mar 3, 2013 at 10:04 PM, Ankit wangoo <ankit.wangoo@xxxxxxxxx>wrote:
>
>> Hi Erdin
>>
>> However that j will cancel out when you will take del cross of E .
>> Suppose E=a*e^j(wt-kz) ,taking curl of E will through up j on other side
>> as well.
>>
>>
>> regards
>> Ankit
>>
>>
>> On Mon, Mar 4, 2013 at 1:02 AM, Ihsan Erdin <erdinih@xxxxxxxxx> wrote:
>>
>>> Ankit,
>>>
>>> Regarding -jw*mu**H*=delcross *E* multiplication of the magnetic field
>>> with the imaginary number j indeed shows the electric and magnetic fields
>>> are 90 degrees out of phase at any point in space.
>>>
>>> Regards.
>>>
>>> Ihsan Erdin
>>>
>>>
>>> On Sun, Mar 3, 2013 at 2:16 PM, Ankit wangoo <ankit.wangoo@xxxxxxxxx>wrote:
>>>
>>>> Hi
>>>> We all know in transmission line structures such as co-axial
>>>> cables, strip-line and micro strip-lines(partially ,if we assume field
>>>> lines remains inside the dielectric) , electromagnetic energy flows in
>>>> TEM
>>>> mode, that is electric and magnetic field are always perpendicular to
>>>> each
>>>> other.
>>>> We also know that characteristics of TEM waves guided by transmission
>>>> lines
>>>> are same as those for uniform plan wave propagating in an unbound
>>>> dielectric medium.
>>>> When we solve Helmholtz equation we find that Electric field can have
>>>> one
>>>> of solution as E=a*e^j(wt-kz) + b*e^j(wt+kz). where first term is a
>>>> forward
>>>> travelling wave and send is backward travelling wave.
>>>> From Ampere circuital law in point form , we can find that H,
>>>> jw*mu**H*=del
>>>> cross *E* . Then H some out to be in phase with E field .That means
>>>> that at
>>>>
>>>> a particular position and at particular time when electric field
>>>> is maximum , magnetic field will also be maximum.
>>>>
>>>> however , when we study standing wave in transmission line which
>>>> is terminated by short.We find that current (magnetic field ) and
>>>> Voltage
>>>> (electric field) are actually completely out of phase. when current is
>>>> max, voltage is zero and vice-versa
>>>>
>>>> What can explain this difference in analysis ?
>>>>
>>>>
>>>> I was thinking more about this,,, standing waves are formed by two waves
>>>> and each of them electric field and magnetic field are in phase.however
>>>> in
>>>> standing wave , because of reflection one of them get polarized in
>>>> different direction such that some points electric field gets cancelled
>>>> and
>>>> some point magnetic field get cancelled.
>>>>
>>>> however ,i am not completely convinced.Can somebody shed some light on
>>>> this
>>>> or refer me to some appropriate reading material?
>>>>
>>>> Thanks for your help
>>>> Ankit wangoo
>>>>
>>>>
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>>>
>>
>
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