Hi!
It's hard to tell what is going on from just one picture...
But it seems like your antenna has no skinning or all the weight is on your bottom joint.
I can't really make out what you are rotating on, but it seems to be the joint rather than the control.
I'm not sure if your joints are supposed to be centered within the controls, but if they are it seems like there is parentblending happening.
probably start your setup from scratch again:
1) Per joint, create a circle and a group
2) parent the circle inside the group
3) move the group so its position matches the joint it corresponds to.
4) parent the last circles group under the second to last circle, then the second to last circles group under the third to last circle and so on. Until all your circles are grouped
5) use the "Constraint -> Parent" command from each circle to the joint it corresponds to
6) select the joints and your antenna, then use the "Skin-> Bind" Skin command
7) the skinning should probably be fine already for such a simple object, otherwise you can fix them using the "Skin -> Paint" Skin Weights tool
This should give you the desired result
I hope it helps!