The underside of a large cylinder is not cling to the earth

Hi Cesium community

I am trying to create a satellite coverage based on this example

But when I create a very large cylinder, it looks as if it is hovering over the earth, what do I have to do to keep its underside close to the ground?

Thank you very much.

You can adjust the height of the position of the cylinder. For instance I modified line 34 in your example.