Theory for a PCB resonator with special kind of mode

[yefj]

Hello ,I have built a resonator in CST as shown bellow .
I need to make the resonator be in such mode so the H-field will be normal to PCB plane.(W diection in the photo).
Surface shows two peaks.
As you can see I have peak magnetic field at the edges.
Is there some PCB way to excite magnetic field peak in the middle of the ring in the direction of W(normal to PCB plane)?
Thanks.

 

[Baluncore]

Is there a ground plane ?
A ground plane would define the electric, not the magnetic field to be vertical.

To excite and maintain a circulating current in the ring, you would need to remove the ground plane below the ring, so that the magnetic field did not cut the ground plane, which is reflecting and cancelling the ring current.

 

[yefj]

Hello,I remove the ground plane under the ring .
I made the substrate invisible so you could see the remaining ground and the excitation with the ring.
I got a very bad magnetic field .
Its not in the W direction ,its not even closely homogeneous.
Is there something that I did wrong?
Thanks.

 

[Baluncore]

It looks to me like you are exciting the ring as two semicircular dipoles, touching at the ends. Maybe the geometry of your coupling is defining that mode. It may require two points of coupling in quadrature, to define the direction of the circular current in the ring.

The ring circumference may have to be much smaller than a wavelength, for a circular current to form in the ring. With a ring circumference equal to one wavelength, the centre will be surrounded by one full cycle of the wave current, so at the centre of the ring, the magnetic field generated the current in the ring, will cancel to zero.

 

[tech99]

I agree with #4. Maybe make the circumference small compared with the wavelength and obtain resonance by cutting the ring and inserting a capacitor.

 

[berkeman]

I need to make the resonator be in such mode so the H-field will be normal to PCB plane.

@yefj -- I have two questions for you:

1. What is your experience level so far with 13+GHz PCB antennas?
2. What is the application?

 

[yefj]

Hello Balunecore,I succseeded to implement your advices and made a breakthrew .
As you can see I removed the ground plane bellow the ring and I got the H-field prepandicular to the plane.
How do you reccomend to increase the coupling to this mode?
Is there some intuitions I could use?
Thanks.

Hello berkerman, regarding your questions:
1. I am not using it as antenna but purely as resonator.
my goal is to build a resonator in 3GHz from a printed ring with H-field normal to the PCB plane.
the 13GHZ is just a starting point.
2. aplication is in research of NV cells, but I am only trying to build the resonator here.
https://www.researchgate.net/public...le-Cell_NMR_Spectroscopy_with_Quantum_Sensors