Yes, the Metox could be detected. I work for RCA and was told the story of a remarkable meeting by a co-worker. He was working with a German engineer on a microwave project when a visiting British engineer came up and looked at what they were doing. The British engineer remarkes that he had worked on microwave and in fact had worked on developing air-born radar for use against the U-boats. The German exclaims "That was you! We realized that you weere using radar so I helped develop the radar detector." The Brit exclaims "That was you! We realized that you had a radar detector, so I helped develop the radar detector detector." The German told the story of the first test of the Metox. He was on the U-boat, they surfaced and set up the equipment. As soon as the Metox was turned on, it went off. He thought it was a fault until the plane attacked. They barely got away. The Brit thought he was on that flight doing tests. It is a small wierd world.

Actually, any receiver tends to transmitt. I have heard that U-boats could locate radio receivers in the early days. Police, here in the states can detect radar dectectors.