What function is the dual-circle antenna?

[tony_lth]

Hi, Gurus,
I saw a dual-circle antenna with the same center.
The inner diameter is about 30mm, and the outer is about 45mm. The circle width are the same, about 3mm.
I guess it maybe a 5.8GHz antenna.
I browsed the internet and some say its a dual-frequency antennas.
I know the antenna should have very narrow directivity, and it should work at free frequency band, such as 2.4GHz, 5.8GHz, 24GHz, etc.
So anyone can comment on this antenna, what it is, and how to design it.
Best,
Tony Liu

 

[aliarifat794]

Use electromagnetic simulation software like CST Microwave Studio, HFSS, or ADS to optimize the antenna design.

 

[tony_lth]

It's a radar antenna. The radar is for small distance detection, and target distance error is expected to mm level.
But with the small available bandwidth of 2.4G or 5.8G or 24G, the error should be big.
So I am curious about: Is the dual circle antenna for dual frequency radars and these radar can make the error small?
Or the dual circles antenna for single radar and their functions are for narrower beamwidth?
Best,
Tony Liu

 

[D.A.(Tony)Stewart]

Can we see what you saw?

 

[tony_lth]

Attachment is the picture of antenna face, and we can see two rings as the antenna. Inner ring diameter is 30mm, and the outer is 45mm.
The radar is a cylinder with 75mm diameter and 75mm height.
The other part are all Aluminum and we can't open it due to lack of the special tools.
The total weight is 450g.
I guess it should not be the lens antenna for 60GHz or 77Ghz, because if so, it should be more weight.
Pls comment on it, thanks.

 

[volker@muehlhaus]

Is it perhaps a circular horn antenna and the "rings" are from stepped diameter?

I mean the simple version of something like this:

Horn antenna - Wikipedia

en.wikipedia.org

 

[vfone]

Or could be a conical horn antenna:

Circular horn efficiency, horn antenna, antenna design