Optimum Operation of Echo Boxes

The parameters determining ring time for an echo box in a radar system are examined, and the conditions for optimum ring time established. Two specific arrangements, namely, the echo box coupled directly to the guide and the echo box coupled through a directional coupler, are treated in detail. Representative curves of ring time as functions of various parameters, and curves of power extracted by the echo box are included. It will be seen that simply increasing the loaded Q of a cavity will not increase the ringing time past a certain maximum, and that there is an optimum value of loaded Q which is a function of the radar power, receiver sensitivity, pulse length, and the method of coupling the cavity to the transmitter.