Re: Back to that drone. On BBC Iran says it electronically hijacked and landed it.
Yes, but to jam effectively, you need to know when and where the drone is coming. And covering that up is the whole point of a stealth drone, isn't it? If you leave your jammer on all the time then you give away its location and capabilities, allowing the enemy to devise countermeasures.
There is one clue in this mystery. Iran is a huge country, much of it covered with inaccessible mountainous or desert terrain. It is highly unlikely the drone just fell out of the sky and they stumbled on to it.
A long time ago, I used to work for an outfit that specialized in electronic warfare, communications and surveillance. I didn't work in that department, I was in image technology and analysis, but you could pick up a little by osmosis.