Microstrip antenna with heterogeneous dielectrica

[Christoph Hörterer]

Hi,
I'd need some help with the calculation and simulation of a rectangular
microstrip antenna.

The question is rather simple. We have a dielectrica of given thickness
and e_r. Now we shall combine it with another material with given e_r.
The thickness shall vary.
These two materials shall be stacked upon each other.

But how to calculate now a resulting e_r_total of both materials?

I know it is very basic and perhaps one should know it, but I can't
remind how to solve this.

Regards,
Christoph

 

[Bob Monsen]

On Sat, 10 Dec 2005 05:24:49 -0800, Christoph Hörterer wrote:
<wants PCB antenna design help>

I stumbled across this recently. Thankfully, I didn't trip.

http://tinyurl.com/8xtmz

Regards,
Bob Monsen

Religion is a solace to many people and it is even conceivable that
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a state of grace and the rest of the world were 'heathens' and by
'heathen' they meant such people as our brother Mahmoud. It meant that
an ignorant, stupid lout who seldom bathed and planted his corn by the
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Our hymn book was loaded with such arrogance mindless, conceited,
self-congratulation on how cozy we were with the Almighty and what a
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was going to catch come Judgment Day.

 

[Christoph Hörterer]

Hi,
I'm sorry. I don't quite understand the mentioned page.
It doesn't really solve my problem.

I searching for a formular or a way how to calculate one epsilon_r from
two different dielectrica with different epsilon_r, as I have seen it
once with capacitors. But I can't remember how to calculate it.
It should be almost the same with microstrip antennas as the are
capacitors, no?

Perhaps I didn't describe my problem very precisely.

 

[Joe McElvenney]

Hi,

The question is rather simple. We have a dielectrica of given thickness
and e_r. Now we shall combine it with another material with given e_r.
The thickness shall vary.
These two materials shall be stacked upon each other.

But how to calculate now a resulting e_r_total of both materials?

In the simple case of two stacked dielectrics (e_r1 & e_r2) of
the same thickness, it would seem to me that the reciprocal of the
resultant e_r might just equal the sum of the reciprocals of both
e_r1 and e_r2. This follows from the simple formula for two
capacitors in series where the presence or absence of the central
plate doesn't change the capacitance.


Cheers - Joe

 

[Joe McElvenney]

Hi,

Ten minutes later I found this -

http://www.phys.uri.edu/~gerhard/PHY204/tsl129.pdf#search='stacked dielectrics'

which uses the alternative form of the expression for two
capacitors in series. All you have to do now is to re-work the
expression for dielectric slabs of differing thicknesses.


Best of luck - Joe

 

[Christoph Hörterer]

Thanks a lot. I think this is it. Just couldn't remember my physics
class ;-)

Regards, Christoph