If someone wanted to learn antenna design and eventually sigint, what resource would you start with?
While doing that I’d either enlist in the US Navy or US Army and work my way into a SIGINT job. Once you’re in a SIGINT job, you’ll be far too busy with radio for ham. This would be a fast track into SIGINT.
After that I’d use my military career to get into the private sector SIGINT world, as there’s a well-worn path there.