short thread radical (no. 52)
幺 represents a tiny, short thread or something small and delicate. As a radical, it carries that sense of thinness or smallness into other characters.
幺 is a pictograph of a tiny, twisted thread or silk filament. The modern form keeps the simple, curved strokes suggesting something small and delicate.
The two small loops and a final stroke look like a short, twisted piece of thread. Picture a tiny silk thread, barely visible, representing something very small.
For ヨウ, imagine a yo-yo made from a short thread: yo -> ヨウ, and the tiny thread spins on the yo-yo.