How to draw a 2D arc in HFSS?

In a tutorial, there is an example for cylinder arc, which is 3D.
how can I draw 2D arc? for example, a 2D rectangle, an arc connects this rectange to another rectange which is 90 degrees to the firs one.
thanks.
PS:picture is attached. drawing circle and a smaller circle then substracting smaller one is a way. there should be easier I guess..

no matter 2D or 3D, this model is composed by 2 rectangule and one quarter of arc which we can get by subtracting two cricle(2D) cylinder(3D),
then choose proper plane to split and unite, we can get this model.
HFSS can support 3D calcualtion, why do you use 2D?

my friend wlcsp warned me about ratios:

"I found that the signal line you designed has a thickness of 1e-5. Try to avoid an aspect ratios(length:thickness) of more than 1000:1"

I mean, I have drawn my design 3D at the beginning, but it did not worked. having detached lines, it worked.
because of that I draw my design 2D.

the thickness of metal line is 0.035 or 0.0175 mm? I do not understand such a big aspect ratio you mentioned comes from where. Do you mean the aspect ratio of length vs. thickness of trace? Yes, the upper limit of HFSS do deal with extremely unregular shape object is around 1000:1,
But I think for you design, if should ok, since there are still other techniques we can employ to cut down computational cost, such as symmetric plane.
Best Regards,

thickness is 4.68mm, so this makes problem.
what is disadventage in using 2D rectangle instead of 3D object?
is this about being realistic?
thanks.