[SI-LIST] Re: Determination of relative permittivity

Just one more comment. :)

> Hi Kai and Matthias,
> This technique is based on cavity perturbation. The
> cavity perturbed by a change in the permittivity
> will
> result in a shift of resonance. The change of
> resonance frequency is given by
> delta_omega/omega_original ~=
> stored_engergy_variation/stored_energy_original;
> where, omega is the angular frequency. Stored_energy
> can be calculated by integrating both the electrical
> energy and magnetic energy.
> Stored_energy =
> Volume_integration(eps*|E|^2+u*|H|^2);
>
stored_energy_variation=volume_integration(delta_eps*|E|^2+delta_u*|H|^2);
> Please be advised that a well designed cavity at a
> specific mode, the field can be theoretically
> calculated and at each mode the field is different.
> However, the perturbation method assumes the field
> distribution will not change, if the dielectric slab
> is thin comparing to the cavity height.
This means under perturbation, the mode will be the
same. Say, if the cavity working at TE101 mode, the
perturbated mode will be the same, regardless of the
resonance frequency changes. Thus a cavity with a
pretty decent band gap between two consecutive
resonance is needed so that the resonance perturbation
resulted from the dielectric won't be masked by the
natural resonance modes of the unperturbed cavity. 

> Hope this is helpful.
> Xin
> 
> 
> 
> --- Kai Keskinen <kalevi@xxxxxxxxxx> wrote:
> > I've lost the reference to an old microwave book
> > that explained the cavity
> > resonance method. One method was to make a disk of
> > the material of a certain
> > thickness that was the same radius as a
> cylindrical
> > microwave cavity. You
> > measured the resonant frequency and cavity Q
> before
> > the disk was inserted
> > and after the disk was inserted into the bottom of
> > the cavity. The change in
> > f gave you the dielectric constant and the change
> in
> > Q gave you your loss
> > tangent. I can't remember the equations to relate
> > delta fr and delta Q to Dk
> > and tan delta. Does anyone else remember this
> > technique? The cavity was
> > cylindrical with a side launch from rectangular
> > waveguide.
> > 
> > -----Original Message-----
> > From: si-list-bounce@xxxxxxxxxxxxx
> > [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of
> > Matthias Bergmann
> > Sent: Wednesday, May 25, 2005 7:32 PM
> > To: si-list@xxxxxxxxxxxxx
> > Subject: [SI-LIST] Determination of relative
> > permittivity
> > 
> > 
> > Hello,
> > 
> > quite a lot of discussions deal about the
> > (effective) permittivity, but how
> > do I determine it ?
> > I would like to measure the complex permittivity
> of
> > synthetic materials in
> > a frequency range between 1 till 500 MHz. I know
> > there are methods like
> > Parallel plate,
> > Reflection wave, S Parameters or Cavity  to
> measure
> > it, but, it's sort of
> > weird,
> > I didn't find any paper which explains how to
> > construct a measurement
> > system.
> > So, are there any basic papers or books you can
> > recommend me ?
> > 
> > Best regards, Matthias Bergmann
> > 
> >
>
------------------------------------------------------------------
> > To unsubscribe from si-list:
> > si-list-request@xxxxxxxxxxxxx with 'unsubscribe'
> in
> > the Subject field
> > 
> > or to administer your membership from a web page,
> go
> > to:
> > http://www.freelists.org/webpage/si-list
> > 
> > For help:
> > si-list-request@xxxxxxxxxxxxx with 'help' in the
> > Subject field
> > 
> > List FAQ wiki page is located at:
> >                
> > http://si-list.org/wiki/wiki.pl?Si-List_FAQ
> > 
> > List technical documents are available at:
> >                 http://www.si-list.org
> > 
> > List archives are viewable at:
> >             http://www.freelists.org/archives/si-list
> > or at our remote archives:
> >             http://groups.yahoo.com/group/si-list/messages
> > Old (prior to June 6, 2001) list archives are
> > viewable at:
> >             http://www.qsl.net/wb6tpu
> > 
> > 
> > 
> > 
> >
>
------------------------------------------------------------------
> > To unsubscribe from si-list:
> > si-list-request@xxxxxxxxxxxxx with 'unsubscribe'
> in
> > the Subject field
> > 
> > or to administer your membership from a web page,
> go
> > to:
> > http://www.freelists.org/webpage/si-list
> > 
> > For help:
> > si-list-request@xxxxxxxxxxxxx with 'help' in the
> > Subject field
> > 
> > List FAQ wiki page is located at:
> >                
> > http://si-list.org/wiki/wiki.pl?Si-List_FAQ
> > 
> > List technical documents are available at:
> >                 http://www.si-list.org
> > 
> > List archives are viewable at:     
> >             http://www.freelists.org/archives/si-list
> > or at our remote archives:
> >             http://groups.yahoo.com/group/si-list/messages
> > Old (prior to June 6, 2001) list archives are
> > viewable at:
> >             http://www.qsl.net/wb6tpu
> >   
> > 
> > 
> 
> Xin Wu, Ph.D
> Special Operations Engineer,
> ICE Electronics Design Solution Division,
> Fluent Inc.--The Right Answer in Fluid..and Wave...
> http://www.icepak.com
> http://www.wam.umd.edu/~xwu
> 
> 
>               
> __________________________________ 
> Do you Yahoo!? 
> Yahoo! Small Business - Try our new Resources site
> http://smallbusiness.yahoo.com/resources/
>
------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in
> the Subject field
> 
> or to administer your membership from a web page, go
> to:
> http://www.freelists.org/webpage/si-list
> 
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the
> Subject field
> 
> List FAQ wiki page is located at:
>                
> http://si-list.org/wiki/wiki.pl?Si-List_FAQ
> 
> List technical documents are available at:
>                 http://www.si-list.org
> 
> List archives are viewable at:     
>               http://www.freelists.org/archives/si-list
> or at our remote archives:
>               http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are
> viewable at:
>               http://www.qsl.net/wb6tpu
>   
> 
> 


Xin Wu, Ph.D
Special Operations Engineer,
ICE Electronics Design Solution Division,
Fluent Inc.--The Right Answer in Fluid..and Wave...
http://www.icepak.com
http://www.wam.umd.edu/~xwu


                
__________________________________ 
Do you Yahoo!? 
Yahoo! Small Business - Try our new Resources site
http://smallbusiness.yahoo.com/resources/
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List FAQ wiki page is located at:
                http://si-list.org/wiki/wiki.pl?Si-List_FAQ

List technical documents are available at:
                http://www.si-list.org

List archives are viewable at:     
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu

Other related posts: