The next isn't mathwise exact but it can be plausible enough
Start by increasing in the preferences the keyboard increment to something substantial, say 5mm instead of for ex. one pixel. Be sure you have smart guides and snap to points ON, no other snaps!
Draw a square
rotate the square 45 degrees
Stretch and squeeze the square to the wanted approximate plane projection size horizontally and vertically. The colored circles are the names of the corners. With the scissors tool cut the shape at the blue corner
With the direct selection tool select the anchors one by one and shift them with the arrow key. There's 2 anchors in the blue corner. Shift the wrong one 1 tick down. You return it later. Shift the rest anchors up:
- green 2 ticks
- red 4 ticks
- orange 6 ticks
- blue 8 ticks
Shift the starting point to its original position; one tick up.
With the node type conversion tool (it's under the pen) drag the nodes to smooth ones. The starting point and the ending point must have approximately identical handles
Make a copy. Drag it to continue the curve. If you drag its starting point when the whole curve is selected, the curve follows. It will snap. Select both curves and join them (Ctrl+J). Smooth the seam with the anchor type conversion tool.
ADD: Nearly any 3D CAD program draws it exacly right with few clicks and save it as 2D SVG or other Illustrator compatible format. This screenshot is from TurboCAD DLX trial (oops, it's CCW, but it can be mirrored)
The curve opened perfectly in Illustrator. CAD makes possible to add the terse curves, too in 3D, if one wants it. Then place the note symbols to the crossings in 2D.