Aperture Coupled Stacked Circular Patch Antenna

I?m trying to design a wide band aperture coupled stacked circular p@tch antenna (Circular p@tches not circularly polarized) for 10 GHz but so far I?m only getting a dual resonance response as shown in the attached file. I tried to optimize: the upper and lower patch (radius, substrate permittivity, substrate thickness), aperture length and stub length. Basically I tried all possible ways but still cannot get wide bandwidth although many papers say it can be done. Any suggestions please?

Thanks
Hassan

hi,
it looks like no one can answer to this specific question, if any one has any papers related to this then please help
Regards,
Hassan

Well, one obvious comment: 14 GHz is the 2nd harmonic of 7, so you may be just seeing a fundamental and harmonic response. If so, try just concentrating on moving the 7.4 GHz response to a higher frequency--ignoring the 2nd harmonic. I would think shorter radius and length. But I am not an antenna guy!

Thank u Piff44,
The design i'm doing is supposed to give me two resonant frequencies as i'm using stacked patches with different radiuses. The problem is that i cannot bring the two resonant frequencies closer to give me wider response although i tried all the optimisation methods i mensioned.

from these two resonance frequency, 7GHz and 14GHz, I suspect that they came from the same p@tch. That means one of your p@tch does not resonant at all, just functioning like capacitive loading to the resonant p@tch. I have no idea about your two p@tches stack up, if they are stacked up in logitudinal direction, have you tried to control the slot openning?

Regards,

each response is from a different patch as
i get about 7 GHz when i do the simulation with the upper patch only(bigger radius)
i get about 14 GHz when i do the simulation with the lower patch only(smaller radius)
i tried changing the slot length. Pozar and other did manage to get a wider BW but i still don't. ANy more suggestions please
Regards,
Hassan

If you can give a figure to illustrate two patches stacking up, it would be easier for me to understand.
Best Regards,

Please find attached a view of the stacked circular patches,
u will find the following layers starting from bottom:
1- air layer
2- feed line layer (h=2mm, εr=6)
3- air gap
4- patch layer (h=1.588mm, εr=2.2)
5- air layer for radiation

thanks
Hassan

Pls check the attached Fig, Did I correctly understand the stack up?
If I am right, I dont think this slot will properly excite the ustrip patches because the air gap can not properly confine the EM wave and form any kind of resonant mode.

Regards,