connecting two resonators in series

[yefj]

Hello , I have built two resonator which are excited and connected with coax lines.
at resonance as you can see below the electric field in much stronger on the line then on the resonators themself.
I know that the coax line acts as a resonator itself, and i get half wavelength pattern.
But why the electric field is much stronger there then on the resonators on the edges?
Thanks.

 

[volker@muehlhaus]

It seems that you are not at resonance frequency of your resonators, so the only resonance that you see is the resonance of the line with mismatch on both ends.

 

[yefj]

Hello Volker, How can you reccomend to improve the matching ?
I have the same coax cable running threw them.

 

[volker@muehlhaus]

As I wrote above, I think that your resonators are not tuned to the correct frequency. Look at S21 of the total structure, maybe that shows something.

 

[D.A.(Tony)Stewart]

It looks like you are at some resonance with standing waves. Are we supposed to guess your assumptions in this plot? Are you looking for max E field or H field? What are your design criteria?

 

[yefj]

Hello Volker,When i have designed those resonators i saw the desired modes.
And i still see them but compared to the coax line the field of the resonator are very weak.

So i will try and tune the first resonantor and i will see the field stronget then the coax?
maybe because the distance between the inner and outer conductors are so small so the E-field is very strong because V=E*d

 

[D.A.(Tony)Stewart]

I wonder if those strips will melt with 746 V/mm. What is the current?

 

[volker@muehlhaus]

So i will try and tune the first resonantor

Before you start tuning, show us your S21 results for the total structure

--- Updated Apr 22, 2024 ---

I wonder if those strips will melt with 746 V/mm. What is the current?

Don't forget that this is simulation only ... The EM tools use some large default value for excitation, such as 1A. It's a linear simulation, so the absolute value can be scaled to your liking.

 

[D.A.(Tony)Stewart]

Before you start tuning, show us your S21 results for the total structure

--- Updated Apr 22, 2024 ---

Don't forget that this is simulation only ... The EM tools use some large default value for excitation, such as 1A. It's a linear simulation, so the absolute value can be scaled to your liking.

Yes Volker, "will melt" meaning future tense. I would expect the stripline to look more robust to handle this power. Wouldn't you?

I might expect 5mm w. over 2.5mm h. of Kapton or alumina or more.

 

[yefj]

Hello Volker S21 and S11 are shown bellow.

 

[volker@muehlhaus]

S21 and S11 are shown bellow.

Ok, there are multiple resonances, and it seems that you 14.41 GHZ E field plot shows one of them.
For which resonance frequencies did you design the two resonators? Do you have S11 and S21 results for the individual resonators also?

--- Updated Apr 23, 2024 ---

more robust to handle this power.

As I wrote above, this is source power a default simulation setting, not the power used in the real circuit. I guess this resonator will be used in the oscillator that yefi is working on.

 

[yefj]

Hello Volker, the S11 S12 of each resonator is shown apart. I know that i somehow need to look for the resonanceswhich are in teh resonantors themself any intuition how to find them?

Another question is how exactly this structure could be used for ? of connecting two resonators in series?
Thanks.
First resonator S-params:

Second resonance:

 

[volker@muehlhaus]

Ok, now I am confused.

You have two resonators with different resonance frequency, and cascade them. Why, what result do you expect?

 

[yefj]

Hello Volker , I assumed that they always will differ .
I thought i could tweak them on the united structure.

 

[volker@muehlhaus]

I thought i could tweak them on the united structure.

Ok, I think tuning is your next step then.

The 14.41 GHz plot that you showed is not the resonance of resonator 1 or resonator 2, that seems to be the resonance of the line with mismatch on both ends.