The devices you call door jammers are not exactly door jammers. The door itself has no frequency to block, but if it can be opened remotely - it has remote control and radio frequency band which controls the process. To jam such remote controls for doors (commonly garage doors) there are special jamming devices - remote control jammers. If the frequency they jam matches with the one that controls the opening and the closing process of the door, it will be blocked. And if there is no other way to open or close the door, you can say that the door is jammed.
Our door jammers can be used not only for garage doors but to jam other kinds of doors if the frequency of their remote control is in the frequency band of the jammer. And except that, they have many other practical appliances.
answered Sep 27 '11 at 07:48