Circular loop microstrip antenna?

[Coust]

Good morning everyone
I have a problem designing a circular loop type antenna. I have thought about making a sandwich of different dielectric /conductor layers and draw a circumference in each dielectric layer (conductor above dielectric) until the total length of the wire matches the frequency of interest (868MHz, 10 layers with a circumference of 6mm radius for each one).

These are my questions:
Can I treat my antenna as a "Circular microstrip ring" type? And if so, which dielectric should I choose a high permittivity one (er) or another with low one?
Which geometry is more interesting for this antenna, one with circumferences of the same radius or a kind of cone (spiral volume)?

Thank you for your time.

 

[Bob60]

(868MHz, 10 layers with a circumference of 6mm radius for each one).
These are my questions:
Can I treat my antenna as a "Circular microstrip ring" type? And if so, which dielectric should I choose a high permittivity one (er) or another with low one?

Yes you can, but it will be only microstrip ring ( some kind of resonator) only and bad as antenna.

 

[Coust]

Yes you can, but it will be only microstrip ring ( some kind of resonator) only and bad as antenna.

Thank you for your answer. Excuse my ignorance in antenna field, I'm just new and I'm a little bit lost at the moment. Why do you think that this kind of antenna will be a poor one? Is it because its small size? These 10 turns should increase the eficiency of the antenna, wouldn't they?

If I can treat it as a microstrip antenna what kind of dielectric should I get to maximize its performance? I read that decreasing Er should increase the eficiency in this kind of antennas. Am I wrong?

 

[Coust]

Does anyone have an idea? Sorry about double post, but I need help as quickly as possible

 

[Bob60]

For the best result antenna should be maximally open without ground plane within 0.1-1λ otherwise antenna ( it it doesn't a part of the antenna ) efficient significantly decrease. Hight ξ dielectric concentrate electric field and decrease propaganda velocity ( kind of time machine ). So, conclusions are: maximal relative dimensions, minimum dielectric. By the way, the best matching has resistor, but he radiate very little.