Helical antenna in HFSS

Hello
I calculated parameters of helical antenna with these values:
N=7 S=250mm H=1.75m C=1m D=318mm (r=159mm)

So I do these steps
1) draw a circle(r=159mm)
2)I select the circle and click the "draw helix" on HFSS toolbar
according to HFSS's help

RadiusChange:The radius change per turn of the helix.
Pitch:Distance between helix turns.
Turns :The number of turns in the helix.

I type these values

but I get this shape!

so what is my mistake?

and could you tell me what is the first vector line that I should define before type the helical values?
and what does the location and size of the line mean?

I will appreciate for your help

You must ensure that the circular polarization of the antenna and the signal matches correctly.

Thanks for your response
but my questions are some things else or I don't understand your comment.
because my design's shape is not the same as other helical antenna and I don't know the first vector line when I want to draw helix loops

Pitch is the distance of one turn from the next, measured along the axis. Your pitch is given as 250mm=25cm and the whole helix will be 25*7cm=1.75m long. If that is the antenna you are planning, it is fine.

I am not following the question in that case. What I meant in the previous post is that the left-handed or right-handed must be selected carefully. How you are going to support 1.75m antenna?

Thanks for your response
In this step I want to simulate this antenna not make it.
Could you tell me...
1)why loops are very big and overlap to each other?
2)define the first vector line when we want to draw a helix
?
Thanks