I suppose the main body of the antenna is a pliable substance like silicone sealer? And you want to embed a tiny connector in the end? I picture your problem being at the contact between metal and silicone. It is subject to stress and flexing. The metal will easily break contact from the silicone.
You need more 'grabbing surface'. I think it would work if you were to encase the connector in a larger epoxy shell. The mold might be a soda straw 1/2 inch long. Hold vertical. Fill with epoxy. Dip the connector down into it. Possibly fabricate some kind of protector so that goo does not get on the threads of the connector.