Simple Microstrip Ring Resonator Design

I'm trying to design a simple microstrip ring resonator for my 9 GHz oscillator. My chosen transistor is biased in such a way that it is operating in the potentially unstable region. The substrate I am currently simulating with is RT Duroid 5880 with a dielectric thickness of 3.175mm. I am simulating my designs using Ansoft Designer.

My goal here is to design a simple (one-port) ring resonator having a reflection coefficient (s11) of:

MAGNITUDE: 0.34
PHASE: -145.14 degrees

So far I already have 2 ring resonator designs (which I originally made) but it doesn't reach the target reflection phase.

DESIGN 1
ring (width=1mm radius=3.27mm) with a coupling gap (width=1mm gap=1mm) and a coupling line (width=1mm length=16.1mm) connected to the port

the reflection coefficient has a magnitude of 0.35 and a phase of -94.72 degrees

DESIGN 2
ring (width=2mm radius=4mm) connected to a coupling line (width=2mm radius=4mm) with a coupling gap (width=2mm gap=1mm) connected to the port

the reflection coefficient has a magnitude of 0.35 and a phase of 10.4 degrees


As you can see, both of my designs almost reached the target magnitude. How can I make the phase close to the target phase without changing the magnitude much?

Thanks and happy holidays!

Can you upload your designs (design1 and design 2) ?

sure!

My adviser also told me to change the length of the coupling line. I tried that but at some point, the magnitude also changes, I guess this is a matter of mixing the right dimensions for the ring as well as the length of the coupling line?

Attached here are my designs:

You should indeed experiment with different layouts. I'm not sure if this might be relevant to your design but you might take these considerations into account

-Current flows in the inside of the rings, therefore always check the meshing density to be dense and convergent
-You might want to try simulating with finite thickness to see if theres any difference
-For your construction, the etch angle (underetch) will have significant impact on resonator loss

Hey I tweak the length and width of the coupling line and achieved a reflection coefficient with a magnitude of 0.39 and a phase of -145.33 degrees. Do you think it is enough to be near that target reflection coefficient? Thanks!

hey saad770 i saw your reply from my email notifications but i can't find your post here

"hay! can i see ur designs because i really need to look them as iim also workiing on it.
and im not able to find the link where u have uploaded ur designs.
kindly please let me know.
thank u so much in anticipation.
κ"

my resonator files are attached above, pls see the previous post

these files are .adsn format. My simulator is Ansoft Designer.

so so thank you . i found ur design